ASCE 41 and the Seismic Retrofit Question — Reference Brief

Subject: seismic evaluation and retrofit for 105 2nd St, Oakland (Alameda County) Prepared: 27 August 2026 · Status: code and standards research, not engineering advice

This is not engineering advice, and it is not a substitute for the standard. ASCE/SEI 41 is a copyrighted document that ASCE sells; nothing in it is reproduced here. There are no tables from the standard in this brief, no acceptance criteria, no m-factors, no provision text. What follows is an explainer, assembled from public sources — ASCE's own descriptions of its standard, the California Building Standards Code (which is public law), FEMA and NIST publications, a City of Los Angeles code bulletin, and two published structural engineers' reports — so that a board member can read an engineer's proposal and report and know what the words mean and which numbers are choices rather than facts. Every substantive claim carries a citation and a retrieval date. Where something could not be verified it is marked [unverified] and says what was searched. Section 8 lists the gaps. Nothing here has been reviewed by a licensed structural engineer.

Why this matters

SquashDrive is buying a ±10,000 sf light-industrial concrete tilt-up building — plus a ±2,000 sf unpermitted mezzanine — and converting it from warehouse use to a squash and after-school tutoring facility. Two facts about that sentence collide.

The first is the building type. Concrete tilt-up buildings with flexible roof diaphragms have a specific, well-documented, repeatedly fatal seismic failure mode: the roof pulls away from the walls. It has recurred in every significant California earthquake since 1971 (§ 5).

The second is the change of use. The California Existing Building Code contains a provision that most people — including many owners — do not know exists: a change of occupancy out of a Group S (storage) occupancy triggers a seismic compliance requirement for the whole building's lateral system, whether or not the building's risk category changes (§ 6). If this building's occupancy of record is Group S — which is what "warehouse" would mean in code terms — that is a mandatory trigger, not a voluntary upgrade. Whether it is Group S has not been established, and § 6.1 explains why that single question is worth answering before anything else.

And the site is in Oakland. The USGS's HayWired scenario — the federal government's own planning scenario for a Bay Area earthquake — puts the epicenter of a magnitude 7.0 Hayward Fault rupture under Oakland, with a 52-mile rupture, ~800 deaths and direct losses above $82 billion. The Bay Area has roughly a 72% chance of at least one M6.7 earthquake before 2043.

— USGS, HayWired Earthquake Scenario fact sheet FS 2018-3016; USGS, The HayWired Scenario (retrieved 27 Aug 2026)

The diligence budget currently carries $5,000 for Structural Assessment, with three open concerns already logged — tilt-up anchorage, panel-opening capacity, and the unpermitted mezzanine (diligence/timeline/index.html). This brief exists so that the board can size that scope deliberately rather than discovering it in a change order. Section 7 explains why $5,000 is probably the right number for the first deliverable and probably not the right number for the one the building department will want.

What the parcel record establishes

Oakland's Land Information Report for APN 001 016501600 / 1-165-16, 105 2nd St answers several questions this brief would otherwise have had to leave open, and opens one it had not asked. Read alongside § 4 (what drives the analysis), § 5 (tilt-up) and § 6 (triggers).

— City of Oakland Land Information Report for 105 2nd St, as supplied to this project (27 Aug 2026). The report is a planning/GIS summary; the individual determinations below carry their own citations.

1969 is the number that matters most

A tilt-up built in 1969 was designed under the 1967 Uniform Building Code or earlier — before the 1971 San Fernando earthquake taught the profession that anchoring a concrete wall to a roof through a wood ledger in cross-grain tension does not work, and before every one of the force-coefficient increases that followed (0.2g → 0.3g in the 1979 UBC → 0.45g in 1991 → 0.63g in 1997; § 5). This building is in the original cohort, not a later one that got some of the fix.

Two direct consequences:

• The wall-anchorage deficiency should be the working assumption, not a hypothesis. Price the evaluation expecting to find it, and ask the engineer to say what it would take to rule it out — most likely a prior retrofit permit (§ 8) or an exposure of the roof-to-wall connection.
• No benchmark shortcut. ASCE 41 lets a building designed to a sufficiently recent code be treated as benchmarked, which among other things allows the knowledge factor κ = 1.0 without further investigation. A 1969 building is nowhere near any benchmark year, so κ = 1.0 has to be bought with drawings and testing (§ 4). That strengthens the case for spending on data collection, not weakens it.

Very High liquefaction, in a Zone of Required Investigation

This is new to the brief and it is not a small item. Two independent things follow.

1. A geotechnical report is a statutory precondition to approval. Under the California Seismic Hazards Mapping Act (Public Resources Code §§ 2690 et seq.):

"Cities and counties shall require, prior to the approval of a project located in a seismic hazard zone, a geotechnical report defining and delineating any seismic hazard."

— PRC § 2697(a) (retrieved 27 Aug 2026)

and the State Mining and Geology Board's criteria, at 14 CCR § 3724:

"A project shall be approved only when the nature and severity of the seismic hazards at the site have been evaluated in a geotechnical report and appropriate mitigation measures have been proposed."

— quoted in CGS Special Publication 117A, Guidelines for Evaluating and Mitigating Seismic Hazards in California, p. 5 (adopted 13 Mar 1997; revised and re-adopted 11 Sept 2008) (retrieved 27 Aug 2026)

The report must be prepared by a registered civil engineer or certified engineering geologist competent in seismic hazard evaluation, must evaluate the hazard site-specifically, must propose mitigation, and the City must forward a copy to the State Geologist within 30 days of approving it (PRC § 2697(a)). A waiver is possible only where the City finds no undue hazard based on studies of nearby sites of similar soil — an unlikely finding on a Very High susceptibility parcel.

Does the exemption apply? Probably not. "Project" excludes:

"alterations or additions to any structure within a seismic hazard zone which do not exceed either 50 percent of the value of the structure or 50 percent of the existing floor area of the structure."

— PRC § 2693(d)(2) (retrieved 27 Aug 2026)

A whole-building conversion touches essentially 100% of the floor area, and this project's own cost model puts construction well above any plausible depreciated value of a 1969 tilt-up shell. On both limbs the exemption looks unavailable — but the 50% tests are the kind of thing a city measures its own way, so confirm the arithmetic with Oakland rather than assuming either result (§ 8).

2. It becomes an input to the ASCE 41 evaluation. ASCE's own description of the standard lists "Foundations and geologic site hazards" among the things it establishes analysis procedures and requirements for. On a Very High susceptibility site the engineer should be asked directly whether geologic site hazards are inside the evaluation scope or excluded from it, and what happens to the foundations if they are not.

— ASCE, ASCE 41-23 introduction PDF (retrieved 27 Aug 2026)

Why this could matter more than the anchorage retrofit. Wall anchorage is repetitive, off-the-shelf hardware at the roof line (§ 5). Liquefaction mitigation is ground work — ground improvement, deep foundations, or a structural response to predicted settlement — under an occupied slab, in a building whose whole floor is the playing surface. It is the one line item identified in this brief with the capacity to change the project's feasibility rather than its budget. It may also be fine: Very High susceptibility is a regional screening classification, not a site-specific finding, and borings frequently come back better than the map. That is exactly what the geotechnical investigation is for, and it is why it should happen early.

One transactional note, outside the seismic question but adjacent to it: PRC § 2694 requires a seller or the seller's agent to disclose that a property lies within a designated seismic hazard zone. Worth confirming that disclosure appears in the PSA package. — PRC § 2694 (retrieved 27 Aug 2026)

1. What ASCE 41 is, and when it applies

The standard

ASCE/SEI 41, Seismic Evaluation and Retrofit of Existing Buildings, published by the American Society of Civil Engineers. ASCE describes it this way:

"Rehabilitation methods used for existing buildings are different from those used in the design of new buildings."

— ASCE, Seismic Evaluation and Retrofit of Existing Buildings, ASCE/SEI 41-23 (ASCE-published introduction, retrieved 27 Aug 2026)

That sentence is the whole point. The code that governs new construction (in California, the California Building Code, which adopts ASCE 7 for seismic loads) tells a designer what to build. It is prescriptive and it assumes a blank site. It cannot be applied literally to a building that already exists, because the building already is what it is — you cannot un-pour a wall. ASCE 41 exists to answer a different question: given this building as it stands, how will it behave, and what would it take to make it behave better?

ASCE 41 is performance-based. Instead of a pass/fail against a prescriptive recipe, it asks the owner to state a target — how much damage is acceptable, in how big an earthquake — and then evaluates the building against that target. That target is the performance objective, and choosing it is a client decision. It is the single most consequential thing the board can influence (§ 3).

The current edition, and the one the user's link points to

The product page supplied for this brief is ASCE/SEI 41-17, Seismic Evaluation and Retrofit of Existing Buildings (41-17), 2017, 550 pages, list price $240–$255.

— ASCE store product page, productId 233163464 (retrieved 27 Aug 2026)

41-17 is not the current edition. The current edition is ASCE/SEI 41-23, published in 2023 (ISBN 978-0-7844-1611-2), list price $255–$297, prepared by the Seismic Evaluation and Retrofit of Existing Buildings Committee of SEI.

— ASCE store, Seismic Evaluation and Retrofit of Existing Buildings (41-23); canonical record at ASCE Library (retrieved 27 Aug 2026). Both ASCE store links may bounce a visitor through an ASCE login before showing the product page.

What changed in 41-23, per ASCE:

• Alignment with the multipoint response spectra in the new USGS seismic hazard model
• Steel and concrete provisions moved out to AISC 342 and ACI 369 rather than living inside ASCE 41
• Revised nonlinear analysis provisions, and new guidance for developing component modeling parameters
• Substantially rewritten masonry provisions, and concrete wall provisions updated "for the first time in over 25 years"

— ASCE introduction PDF; ASCE, "ASCE 41-23 provides significant updates…", Civil Engineering Source, 1 Dec 2023 (retrieved 27 Aug 2026)

ASCE revises on a roughly five-year cycle ("Standards development is generally on a five-year cycle to revise or reaffirm existing standards" — ASCE introduction PDF), and older editions stay alive in code for years: the 2025 CEBC's referenced-standards chapter lists 41-13, 41-17 and 41-23. Editions matter for two reasons: results are not interchangeable between them, and the building department, not the engineer, decides which edition applies. Ask which edition a proposal is priced against and confirm it with Oakland (§ 8, item 1).

What ASCE 41 is not

• It is not a building code. It is a referenced standard. It has force only where a code or ordinance points to it — which the California Existing Building Code does (§ 6).
• It is not a pass/fail rating of a building. It is a pass/fail against a stated objective. "The building passes ASCE 41" is a meaningless sentence until you know which objective and which hazard level.
• It is not a substitute for a geotechnical report. Site class, liquefaction, landslide and fault-rupture hazards are geotechnical inputs the evaluation consumes. Both published example reports in § 7 lean on separate geotechnical studies.

2. The tiered process

ASCE 41 has three tiers. ASCE's own summary of the trade-off is the most useful sentence anyone has written about it:

"…three different tiers of evaluation and retrofit approach, with each tier being more engineering-intensive but less conservative."

— Robert Pekelnicky, chair of the ASCE 41 standards committee, quoted in Civil Engineering Source, 1 Dec 2023 (retrieved 27 Aug 2026)

Read that as: more fee, less steel. A cheap evaluation is a conservative evaluation, and conservatism in an evaluation shows up as construction cost. The tiers are a dial between engineering hours and retrofit scope, and the right setting depends on how big the retrofit is likely to be.

Sources: ASCE describes the standard as presenting "a three-tiered process for seismic evaluation" in which Tier 1 "focuses on identifying potential deficiencies in existing buildings based on the performance of similar buildings in past earthquakes," and the deficiency-based procedures "allow evaluation and retrofit efforts to focus on specific potential deficiencies deemed to be of concern for a specified set of building types and heights," while "the systematic procedure, applicable to any building, sets forth a methodology to evaluate the entire building in a rigorous manner." — ASCE, ASCE 41 standard page; ASCE introduction PDF (retrieved 27 Aug 2026). Tiers map to the standard's Chapters 4, 5 and 6 respectively — ProtaStructure, Design Guide: Assessment & PBD to ASCE/SEI 41, May 2025, p. 13 (retrieved 27 Aug 2026)

Two further points that change how a proposal reads:

• The tiers are not required to be climbed in order. A Tier 3 systematic evaluation can be chosen from the outset. In practice Tier 1 is usually run first because it is cheap and it scopes everything after it.
• Tier 1 and Tier 2 use a single-level assessment; Tier 3 uses two. For Tiers 1 and 2 the basic objective requires one hazard level to be checked; Tier 3 checks two, the second at the rarer, larger earthquake. This is a real difference in what the answer means, not just in cost. — ASCE, ASCE/SEI 41-23 Tier 1 and Tier 2 Updates, course description (retrieved 27 Aug 2026)

ASCE publishes the Tier 1 checklists separately from the standard — for 41-17 as fillable PDF forms covering "a variety of building types and seismicity levels," and for 41-23 as a companion resource released on ASCE's AMPLIFY platform. — ASCE introduction PDF; Civil Engineering Source, 1 Dec 2023 (retrieved 27 Aug 2026)

Which tier fits this building

For understanding the building and pricing the retrofit, Tier 1 is the right first spend: a one-story tilt-up with a flexible roof diaphragm is close to the archetype the screening checklists were built around, and the deficiencies it will flag are predictable (§ 5).

For code compliance under a change of occupancy, Tier 1 will not be enough. Both California code paths that permit ASCE 41 for a change of occupancy name a Tier 3 procedure (§ 6). Budget accordingly: the screening report and the compliance report are two different deliverables at two different price points.

3. Performance objectives — the board's lever

This is the section to read twice.

A performance objective is a pair

A performance objective in ASCE 41 is one or more pairings of a seismic hazard level (how big an earthquake) with a target performance level (how much damage is acceptable in it). An engineer's report should state this explicitly near the front. Here is how a real one does it, for a fire station:

"The performance objective consists of one or more pairings of a selected Seismic Hazard Level with a target Structural Performance Level and Nonstructural Performance Level."

— IDA Structural Engineers, Conceptual Retrofit Design based on ASCE 41-17 Tier 1 and 2 Seismic Evaluation, Kensington Public Safety Building, 5 September 2019, § 2 — PDF (retrieved 27 Aug 2026)

If a proposal you are handed does not name the hazard levels and the performance levels, it has not told you what it is going to check.

The performance-level ladder

The California code's own tables name the structural performance levels, in descending order of protection:

— level names and codes as printed in California Existing Building Code Tables 304.3.1 and 304.3.2, reproduced in LADBS Information Bulletin P/BC 2026-148, Procedures for the Application of ASCE 41-23 to Existing Buildings, eff. 1 Jan 2026, rev. 3 Apr 2026 (retrieved 27 Aug 2026). The plain-language description of Immediate Occupancy is paraphrased from the IDA report § 2.1.1, cited above.

Two clarifications the board will need:

• "Operational" is not on that list, and that is not an error. Operational is a building performance level — Immediate Occupancy structure plus nonstructural systems that keep working. There is a parallel ladder of nonstructural performance levels (e.g. 1-B Position Retention, 3-D Hazards Reduced), and the Operational building level is the top of the combined ladder. The IDA report is explicit that its objective "provides most of the protection obtained under the Operational Building Performance Level without the added cost of providing standby utilities and performing rigorous seismic qualification of building equipment performance" (§ 2). Operational costs real money in generators, bracing and equipment qualification, and it is not something a squash facility needs.
• Nonstructural scope is separately priced and frequently omitted. The IDA report says plainly: "An evaluation of non-structural elements and systems were not included as part of the scope of this evaluation" (§ 2.1.2). For this project the nonstructural scope is not trivial — suspended ceilings, lighting and equipment over courts where children will be standing. Ask whether it is in or out.

The hazard levels

Four designations recur. The E ones are the existing-building hazards; the N ones are the new-building hazards.

— return periods and probabilities per IDA, Kensington Public Safety Building, § 2.1.3 (cited above); BSE-1E/BSE-2E probabilities corroborated in Degenkolb Engineers, memo to Oregon Seismic Rehabilitation Grant Program, "ASCE 41-17 Implementation", 13 July 2018; BSE-1N = ⅔ × BSE-2N per ProtaStructure design guide, p. 10 (all retrieved 27 Aug 2026)

The E hazards are smaller earthquakes than the N hazards. That is the entire difference between the two basic objectives.

BPOE versus BPON — what the choice actually is

• BPOE — Basic Performance Objective for Existing Buildings. The performance levels above, checked against the E (existing-building) hazards.
• BPON — Basic Performance Objective Equivalent to New Building Standards. The same performance levels, checked against the N (new-building) hazards.

Look at the California tables and the point becomes vivid: Tables 304.3.1 and 304.3.2 specify the same performance levels for each risk category. For Risk Category II both say Life Safety at the lower hazard and Collapse Prevention at the upper one. The only difference between "full seismic criteria" and "reduced seismic criteria" is which earthquake you check them against — N or E.

— LADBS P/BC 2026-148, Tables 304.3.1 and 304.3.2 as reproduced (retrieved 27 Aug 2026)

The honest framing of what BPOE buys and costs, from a working engineer's report:

"The BPOE for existing buildings is a slightly lower category which may result in a lower level of safety and a higher probability of collapse than what may be provided by building codes for new buildings. Buildings meeting the BPOE are expected to incur very little damage from relatively frequent, small to moderate earthquakes but are expected to incur greater levels of damage and economic loss from severe earthquakes."

— IDA, Kensington Public Safety Building, § 2 (cited above)

And the rationale for permitting the lower bar at all:

"The increase in seismic risk is tempered by the recognition that existing buildings often have a shorter remaining useful lifespan than new buildings … The standard also recognizes that the cost of achieving smaller probability of damage caused by the higher level of performance is often disproportionate to the incremental cost."

— IDA, Kensington Public Safety Building, § 2

What a higher objective buys, and why it is the board's call

Moving from BPOE to BPON, or from Life Safety to Immediate Occupancy, buys less damage and a faster return to operation after a large earthquake — not, primarily, fewer deaths. Life Safety already targets "people get out."

For SquashDrive the relevant question is not really about collapse. It is: if the Hayward Fault ruptures and the building survives at Life Safety, is the program over? A Life Safety building after a major event may be standing, unusable, and not economically repairable. A capital campaign that funded a building that is a write-off after an earthquake — with children's programming suspended indefinitely and no insurance-driven path back — is a mission risk, not merely a property risk. That is a board judgment, and it is the reason the objective is the board's decision and not the engineer's.

Two cautions on the other side:

• Above the code minimum, you pay for the increment yourself. Nothing compels a higher objective. Every dollar of it is a fundraising dollar.
• A higher objective changes the retrofit, not just the paperwork. It can move a scope from "anchors and cross-ties" to "new lateral elements," and the second is a different order of cost.

The practical move: ask the engineer to price the evaluation so it reports results at both the reduced and full criteria. The marginal cost of reporting a second objective off the same model is far smaller than the cost of a second engagement, and it converts an abstract governance question into two numbers the board can choose between.

4. What drives the analysis, and the fee

Risk category

Risk Category is a code classification of consequence-of-failure, I through IV, and it drives the required performance objective. California Building Code Table 1604.5 sets it. The entries that could matter here:

• Risk Category II — "Buildings and other structures except those listed in Risk Categories I, III and IV." The default.
• Risk Category III includes, among others: "Buildings and other structures whose primary occupancy is public assembly with an occupant load greater than 300"; "Buildings and other structures containing Group E or Group I-4 occupancies or combination thereof, with an occupant load greater than 250."
• Risk Category IV — essential facilities: hospitals, fire and police stations, emergency operations. Not this building.

— California Building Code 2025, Table 1604.5 (retrieved 27 Aug 2026)

Both California tables step the objective up at Risk Category III (Damage Control at the lower hazard, Limited Safety at the upper), so crossing that line is a real cost event. Section 6 works the occupant-load arithmetic.

Data collection and the knowledge factor — why paying for investigation saves money

This is the most counterintuitive and most useful mechanic in the standard for an owner.

ASCE 41 applies a knowledge factor, κ, that scales down computed component capacities to account for uncertainty about what is actually in the building. Less knowledge, lower capacities, more apparent deficiency, more retrofit. The standard defines three data-collection levels:

• Comprehensive — complete and accurate information: detailed construction drawings plus comprehensive material testing
• Usual — partial information, supported by field verification and testing
• Minimum — limited or unreliable information, requiring extensive assumptions

Where material properties are missing from the drawings, default values may be used with κ = 0.75; where inspection or test records validate the drawings, κ = 1.0.

— ProtaStructure, Design Guide: Assessment & PBD to ASCE/SEI 41, May 2025, pp. 14–15, summarizing ASCE 41-17 § 6.2.4 and Table 6-1 (retrieved 27 Aug 2026)

There is one shortcut, and this building does not get it: a structure that meets the standard's benchmarking requirements qualifies for κ = 1.0 outright. A 1969 building is far too old for any benchmark, so here κ = 1.0 has to be earned by investigation.

The arithmetic for the board: κ = 0.75 versus κ = 1.0 is a 25% haircut on computed capacity across the affected components. Concrete cores, rebar scanning, ledger and anchor exposure, and drawing recovery are four-figure to low-five-figure line items. Getting the analysis out from under a 25% penalty on a building where the retrofit is a six- or seven-figure item is very likely a positive-return investment.

So: find the drawings. Original permit drawings, structural calculations, any prior tilt-up anchorage retrofit, the roof-replacement history. Ask the seller in diligence, and ask the City of Oakland for the permit file. The published example reports show how much this matters — the Kensington report lists five sets of prior drawings it was able to review; where it lacked them, it had to assume "the presence of nominally nailed plywood" and the walls then failed the check (IDA § 7, § 9.3). Missing information becomes a deficiency.

Related and separate: the unpermitted mezzanine has, by definition, no permitted structural design to review. Whatever knowledge level applies to the rest of the building, the mezzanine starts at the bottom of the ladder. Legalizing it will require an engineer to design it as if new. That is already a logged high-severity diligence concern and this brief does not improve it.

The analysis ladder

Within a Tier 3 systematic evaluation, four analysis procedures are available, in increasing order of effort and decreasing order of conservatism:

Which are permitted depends on the building's period and its irregularities; LADBS publishes a permitted/not-permitted matrix keyed to those characteristics, and requires a seismic peer review panel for nonlinear work.

— LADBS P/BC 2026-148, § C and note 5 (retrieved 27 Aug 2026)

For a one-story tilt-up, a linear procedure is the expected starting point. Nonlinear analysis on a building this size would be unusual, and a proposal that leads with it deserves a question.

A caveat worth knowing before you read a failing result

ASCE 41's linear component-based procedures can be conservative. A NIST-authored study applied ASCE 41-17 to a building that complied with ASCE 7 and AISI S400 and had "successfully withstood shake table testing in excess of maximum considered earthquake levels with no permanent damage and no residual drift" — and ASCE 41-17 still "finds the building to be deficient," because "the component-based procedures of ASCE 41 do not easily account for the larger system overstrength and ductility" of real systems.

— M.S. Speicher, Z. Zhang and B.W. Schafer, "Application of ASCE 41 to a two-story CFS building," Proceedings of the Cold-Formed Steel Research Consortium Colloquium, 20–22 October 2020 — PDF (retrieved 27 Aug 2026)

That study is about cold-formed steel, not tilt-up, and it is a research finding, not a licence to ignore a result. But it is the reason the tier and procedure selection matters: a deficiency found at a low tier with a low knowledge factor by a linear procedure is a candidate deficiency. Before buying steel, it is often cheaper to buy more analysis.

5. Tilt-up buildings specifically

If you read only one technical section, read this one. It is the most likely single line item in a retrofit scope for this building.

The building type

A concrete tilt-up warehouse is a rigid wall–flexible diaphragm (RWFD) building: heavy concrete perimeter walls, and a light, flexible roof — plywood or steel deck on wood or steel framing — spanning between them. FEMA describes RWFD buildings as "ubiquitous across North America," commonly taking the form of concrete tilt-up and masonry "big-box" buildings used for retail, storage and distribution.

Early California tilt-ups typically had 5–6 inch concrete perimeter walls, plywood roof sheathing, wood sub-purlins and purlins, glu-laminated timber girders and steel columns.

— John Dal Pino, "Seismic Retrofit Ordinances Part 3: Concrete Tilt-up & Wood Soft-Story," STRUCTURE magazine, 31 March 2025 — article (retrieved 27 Aug 2026)

The failure mode

The walls are not the problem. The connection between the roof and the walls is.

In an earthquake the heavy concrete wall wants to move out of plane, away from the building. The roof diaphragm has to hold it back. In older construction that restraint was delivered through the wood ledger — the timber bolted along the inside face of the wall that the roof framing sits on — loading it in cross-grain tension and bending, a direction in which wood is weak and brittle. The ledger splits, the anchorage releases, and the wall falls away from the roof; with its support gone at the perimeter, the roof comes down.

"…large numbers of concrete tilt-up warehouse buildings had partial roof collapses" in the 1971 San Fernando earthquake, from "a design flaw that relied upon wood ledgers in cross-grain tension/bending for anchorage of the wall to the roof diaphragm."

— John W. Lawson, "Revisiting Earthquake Lessons: Wall Anchorage to Flexible Diaphragms," SEAOC, 1 August 2018 — record (retrieved 27 Aug 2026)

Why it keeps recurring

Because each earthquake exposed a different half of the problem, and the code chased it:

— Lawson, op. cit.; FEMA P-1026 as summarized in the same literature

Required anchorage force coefficients climbed from 0.2g to 0.3g in the 1979 UBC, to 0.45g in the 1991 UBC, to 0.63g in the 1997 UBC — and Northridge showed the increases "had not gotten to the root of the problem" (Dal Pino, op. cit.).

This building is dated 1969, which places it before the first of those steps and before San Fernando exposed the flaw at all. It is in the original cohort. Treat the anchorage deficiency as the expected finding rather than a possibility — see "What the parcel record establishes."

The physical reason the demands are so high: a flexible roof diaphragm amplifies ground motion. Recorded motions in flexible-diaphragm structures amplify roughly 1.5× at the roof edges and 4–5× at the centre of the diaphragm. During Northridge, roof-level accelerations in single-story warehouses ran three to four times the ground acceleration.

— FEMA P-1026, Seismic Design of Rigid Wall–Flexible Diaphragm Buildings: An Alternative Procedure, 2nd ed., October 2021, as described in the secondary literature; ATC store listing for FEMA P-1026 (retrieved 27 Aug 2026)

[unverified] — The FEMA P-1026 PDF itself returned HTTP 403 to automated retrieval on 27 Aug 2026; the amplification figures above are taken from secondary summaries of it, not read in the source. Treat them as indicative of the mechanism, not as design values.

What the retrofit typically involves

The good news is that this is a well-trodden, relatively cheap retrofit compared to, say, a non-ductile concrete frame:

"The retrofit of tilt-ups is a quite straightforward affair, often done in two phases. The first phase involves adding or increasing the strength of the out-of-plane wall anchors and creating diaphragm cross-ties using off-the-shelf holdown anchors."

— Dal Pino, STRUCTURE, 31 March 2025 (cited above)

In practice, phase one is: new wall anchors through the concrete panels into the roof framing, subdiaphragms and continuity ties so the anchorage force is dragged into the body of the roof rather than dumped at the edge, and hardware that engages the framing in a direction wood is strong in. Dal Pino notes phase one is achievable by two carpenters with basic equipment. Phase two is improving the diaphragm nailing, "usually put off until the next re-roofing project when the cost of additional nailing is small as a percentage of the entire project."

Two things about that for this project. First, wall anchors and cross-ties are inside work at roof level — they interact directly with a court layout, with lighting, and with any ceiling. Sequence them before finishes, not after. Second, if the roof is being replaced anyway (a live question for a building of this age), the diaphragm nailing upgrade rides along at marginal cost. Coordinate the structural scope with the roof decision; done in the wrong order it is two mobilizations.

One caution on scope

Wall anchorage is the headline deficiency, not the only one. For this specific building the diligence tracker already flags that "interior demising wall and panel openings constrain where courts can go; capacity of the modified panels is unverified." Panel openings — existing ones, and any new ones cut for doors or glazing — change the in-plane capacity of the wall and are a separate check. Any new opening cut in a tilt-up panel is a structural modification.

6. What triggers a retrofit obligation — the change-of-occupancy finding

This is the most consequential section for the project budget. Read it with the engineer and, before relying on it, with Oakland's plan check.

The finding, stated plainly

A change of occupancy out of a Group S (storage) occupancy triggers a seismic compliance requirement for the building's lateral force-resisting system under the California Existing Building Code — whether or not the risk category changes. If this building's occupancy of record is Group S, that is a mandatory trigger on the face of the code, and it applies under both of the compliance methods a project of this kind would plausibly use.

If the risk category does not change, the code permits the reduced seismic criteria rather than the full new-building criteria — which is a materially cheaper outcome, and which makes the occupant-load question below worth real attention.

Everything in this section is conditioned on the building actually being Group S. It has not been confirmed that it is, and § 6.1 is therefore the first thing to resolve.

6.1 First: is the building actually Group S?

The project's own documents describe the building two different ways — a "warehouse" in the repository's project notes, a "light-industrial building" in the welfare exemption brief. Those are colloquial and zoning-flavoured descriptors. Neither is a building-code occupancy classification, and the trigger turns on the classification.

The code draws a clean line between the two candidates:

Group S (Storage) — "the use of a building or structure, or a portion thereof, for storage that is not classified as a hazardous occupancy" (CBC § 311.1). S-1 is moderate-hazard (combustible) storage; S-2 is low-hazard (noncombustible) storage.

Group F (Factory Industrial) — "the use of a building or structure, or a portion thereof, for assembling, disassembling, fabricating, finishing, manufacturing, packaging, repair or processing operations that are not classified as a Group H hazardous or Group S storage occupancy" (CBC § 306.1). F-1 is moderate-hazard, F-2 low-hazard.

— § 306.1 read directly in CBC 2025 Chapter 3. The § 311.1 sentence and the § 311.2 S-1 commodity list were read in the model IBC rendering and § 311.2 rather than in the California text, which would not render that far; whether California amends § 311 is [unverified], though nothing suggests it does. (retrieved 27 Aug 2026)

"Light industrial" straddles the line. A distribution or warehousing tenancy is Group S. A light-manufacturing, fabrication or repair tenancy is Group F. And § 506.5.3's special clause names Group S or Group U only — it does not name Group F. So:

Group F is weakly better in every cell — strictly better if the risk category holds at II, identical if it does not. Exception 2 cannot rescue either Risk Category III cell here, because it requires S_DS < 0.33.

Two wrinkles:

• A mixed-occupancy building does not obviously escape. If any portion is legally Group S and that portion is changing, the clause reads as firing. LADBS proposed an Exception 5 for precisely that case — an ancillary Group S or U area converted to the building's primary occupancy, with no change of risk category — and it is not in the adopted CEBC text; only four exceptions survived. Do not assume relief for an ancillary storage area.
• Zoning is a different question with a different answer — and the parcel record answers it favourably. The site is zoned D-DT-C, a Downtown District zone, not an industrial one; the "light industrial" label is the assessor's use code for the existing building, which is a valuation category and not a code occupancy classification. Oakland's D-DT regulations appear to contemplate Community Education, Community Assembly and Recreational Assembly Civic Activities, which is the right neighbourhood for a nonprofit squash-and-tutoring facility — but the activity classification and its permit path are a planning determination, and the D-DT chapter could not be retrieved directly [unverified — see § 8]. Either way, none of it bears on § 506.5.3. — Oakland Planning Code Ch. 17.101K, D-DT Downtown District Zones Regulations

How to answer it. The classification of record comes from the Certificate of Occupancy, or failing that the use stated on the last building permit — not from the listing, the assessor's use code, or the zoning designation. It is the cheapest question in this brief and, on the matrix above, the one with the largest spread between outcomes.

6.2 Where to actually get the Certificate of Occupancy

Four channels, in the order worth trying. The same request should sweep up the structural drawings (§ 4) and any prior anchorage-retrofit permit (§ 8, item 8) — it is one errand, not three.

1. Ask the seller. Free, fastest, and they may simply have it. Make the C of O, the original permit set and structural calculations, and the roof and retrofit permit history explicit delivery items in the PSA, not a polite request. If the seller cannot produce a C of O, that itself is informative.

2. Oakland's Online Permit Center (Accela) — free, no login, self-serve. aca-prod.accela.com/OAKLAND. Per the City's own FAQ: "You can view general Building, Code Enforcement & Planning records after 1987 by visiting our Online Permit Center (no login required)."

The catch and the opportunity are the same fact. This building is dated 1969, so the original permit and any original C of O will not be here. But the Bay Area's voluntary tilt-up anchorage retrofits mostly happened in the decade after Loma Prieta (1989) and Northridge (1994) — squarely inside the online window. Run the address anyway: a hit answers § 8 item 8 in five minutes and would materially change the retrofit scope and cost.

(Checked 27 Aug 2026: the portal was returning a scheduled-maintenance page. Retry.)

3. Public Records Act request, for anything pre-1987 and for plans. oaklandca.nextrequest.com → "Make Request", describe the records, select Planning & Building. Two tips:

• Search the portal before requesting. The City says all previous requests and responsive documents are posted there — over 116,000 of them. Someone may already have pulled this parcel's file.
• Plans are a two-step process. The PRA request comes first; staff locate the plans and contact you, then you book a viewing appointment. Getting copies additionally requires signed authorizations — a Requestor Affidavit, a Professional of Record form, and a Property Owner form. Budget calendar time: the statutory response clock is short, but physically retrieving 1960s-era records is not.

4. The Records Unit directly, for a 1969 building where the file may be microfilm and a human needs to look: RecordsInfo@oaklandca.gov, 510-238-3606, Planning & Building Department Records Unit, 250 Frank H. Ogawa Plaza, 2nd Floor, Oakland CA 94612.

Do not order a 3-R Report. It is a Report of Residential Record — residential properties only, so it is the wrong instrument here — and for a pre-1998 building it costs $3,330.33 with a two-month turnaround and requires proof of ownership.

— all of the above from City of Oakland, Planning & Building Records Requests (retrieved 27 Aug 2026)

If there is no Certificate of Occupancy at all. Entirely possible for a 1969 industrial building; C of Os were not issued or retained consistently in that era. Then the evidence of legal occupancy is the original building permit's stated use plus every permit since, and the classification becomes a determination the AHJ makes rather than a document you retrieve — which is another reason for the pre-application meeting in "What could change this answer."

Know also that Oakland has an Application for Re-issuance of a Certificate of Occupancy covering an expired, missing or revoked CO — a $1,609.00 non-refundable application fee, conditioned on a permit-record report, all required permits and approvals being current, and passing both permit and certificate-of- occupancy final inspections, and signable only by the record owner or a notarized agent. That is an owner-level remediation project with live inspection exposure, not a diligence lookup — and it is much better discovered before closing than after. — City of Oakland, Application for Re-issuance of a Certificate of Occupancy, April 2024 (retrieved 27 Aug 2026)

The form adds that its fees "do not include 14.25% Technology and Records Management Fee." That percentage is applied to the other fees, not to the project's value. Oakland's zoning fee schedule describes the same charge as a "Technology Enhancement / Records Management Fee … a percentage calculation based on the other fixed fees," and its worked lines confirm the arithmetic — a $1,647.00 fee carries $242.93, which is exactly 14.75% of the fee. So on the C of O application the surcharge is roughly $229, for about $1,838 all-in.

Note the two different rates: the C of O form (April 2024) says 14.25%, the zoning schedule says 14.75%. The rate is reset in Oakland's annual Master Fee Schedule, so treat any figure here as indicative and confirm the current one at application. Every fee in this section is on the same footing — none of them is a quote. — City of Oakland, Zoning Permit Fees Schedule (rev. 21 Feb 2023; a FY2025-26 schedule exists but would not retrieve) (retrieved 27 Aug 2026)

The code path, step by step

Step 1 — which code. California adopts the model International Existing Building Code with amendments, as the California Existing Building Code (CEBC), Title 24 Part 10. The 2025 edition took effect 1 January 2026. Oakland adopted the 2025 California model codes with local amendments by ordinance (File #26-0024, "Local Amendments To 2025 California Model Building Construction Codes," passed 15 September 2025), repealing its 2022 amendments.

— DGS Building Standards Commission, 2025 Title 24 code changes; City of Oakland, Adoption of 2025 California Building Codes; Oakland File #26-0024 (retrieved 27 Aug 2026)

Step 2 — which compliance method. CEBC § 301.3 offers three, and they "shall not be applied in combination with each other": prescriptive (Chapter 5), work area (Chapters 6–12), or performance (Chapter 13). The applicant chooses.

— CEBC 2025 § 301.3 (retrieved 27 Aug 2026)

Step 3 — the trigger, which is in both of the first two methods. The prescriptive method's § 506.5.3 and the work-area method's § 1006.3 carry the same sentence:

"Where a change of occupancy results in a building being assigned to a higher risk category, or where the change is from a Group S or Group U occupancy to any occupancy other than Group S or Group U, the lateral force-resisting system of the building shall comply with Section 304.3.1 for the new risk category." (emphasis added)

— CEBC 2025 § 506.5.3 and § 1006.3 (retrieved 27 Aug 2026)

Step 4 — the exceptions, and which one is ours. Four exceptions accompany § 506.5.3. Taking them in turn against this building:

— CEBC 2025 § 506.5.3, Exceptions 1–4 (retrieved 27 Aug 2026). The Chapter 10 version carries the same set with Exception 3 "Reserved."

Step 5 — what compliance then means. Section 304 sets the two criteria levels, and each offers an ASCE 41 alternative:

• § 304.3.1, full seismic criteria. Either CBC § 1613 using ASCE 7 "Ordinary" system values, or "ASCE 41, using a Tier 3 procedure and both levels of the two-level performance objective in Table 304.3.1" — for Risk Category II, Life Safety at BSE-1N and Collapse Prevention at BSE-2N.
• § 304.3.2, reduced seismic criteria. CBC § 1613 at 75% of prescribed forces, or an applicable Appendix A chapter, or "ASCE 41, using the performance objective in Table 304.3.2" — for Risk Category II, Life Safety at BSE-1E and Collapse Prevention at BSE-2E.

— CEBC 2025 §§ 304.3, 304.3.1, 304.3.2 and Tables 304.3.1, 304.3.2; tables corroborated in LADBS P/BC 2026-148 (retrieved 27 Aug 2026)

So the practical target is: stay in Risk Category II, take Exception 4, and comply via § 304.3.2 using ASCE 41 at the BPOE-equivalent objective. Which puts the occupant-load question squarely on the critical path.

Where the Group S clause came from

Worth knowing, because an engineer or plan checker working from an older edition may not have it. The 2021 model IEBC § 506.5.3 read only:

"Where a change of occupancy results in a building being assigned to a higher risk category, the building shall satisfy the requirements of Section 1613 of the Building Code for the new risk category using full seismic forces."

— 2021 IEBC § 506.5.3, as reproduced at UpCodes (retrieved 27 Aug 2026)

The Group S/U clause appears in the 2022 CEBC § 506.5.3 marked [BS] as a California building-standards amendment, and by the 2024 model IEBC it had reached the model code — LADBS's own public comment on the 2025 California cycle described the "current language in 2024 IEBC" as not allowing conversion of Group U or Group S occupancies "without having the entire building satisfy the requirement of section 1613 of CBC," and proposed narrowing it for small ADR/ADU-scale conversions.

— 2022 CEBC § 506.5.3; Shahen Akelyan (LADBS), public comment to the California Building Standards Commission on the 2025 CEBC, 9 October 2024 (retrieved 27 Aug 2026)

Note what that comment implies: the profession reads this clause as broad, and the relief it sought was for small conversions — a 10%-of-area office in a parking garage, a garage-to-ADU. A whole-building warehouse-to-assembly conversion is not what anyone was trying to exempt.

Does the risk category change? The occupant-load arithmetic

This is the fork between § 304.3.1 (full) and § 304.3.2 (reduced), and it turns on occupant load, which is a design output — meaning it is partly within the project's control.

Occupancy classifications, per the 2025 California Building Code:

• Group A-3 expressly includes "Gymnasiums (without spectator seating)" and "Indoor tennis courts (without spectator seating)" — the closest listed analogue to a squash court (CBC § 303.4)
• Group B includes "Training and skill development not in a school or academic program (this shall include, but not be limited to, tutoring centers, martial arts studios, gymnastics and similar uses regardless of the ages served, and where not classified as a Group A occupancy)" (CBC § 304.1)
• Group E covers use "for educational purposes through the 12th grade" by more than six persons at a time (CBC § 305.1)

— CBC 2025 Chapter 3 (retrieved 27 Aug 2026)

Whether an after-school tutoring program is Group E or Group B is a genuine question with a code consequence — Group E carries the 250-occupant Risk Category III threshold. The § 304.1 language ("tutoring centers … regardless of the ages served") reads toward Group B for a program that is not a school, but that is a plan-check determination, not one to settle in a memo. [unverified]

Occupant-load factors, CBC Table 1004.5: Exercise rooms 50 gross; Educational classroom area 20 net; Business areas 150 gross; Assembly without fixed seats — standing space 5 net, concentrated (chairs, not fixed) 7 net, unconcentrated (tables and chairs) 15 net; Warehouses 500 gross.

— CBC 2025 Table 1004.5 (retrieved 27 Aug 2026)

An illustrative calculation on ±12,000 sf, using this project's own program shape — not a code determination:

That lands under the 300-occupant public-assembly threshold and well under the 250-occupant Group E threshold — i.e. Risk Category II, no change, Exception 4 available. But the margin is roughly 20%, and it is sensitive to decisions nobody has made yet: whether any area is computed as assembly seating or standing space (5 to 15 net rather than 50 gross), whether a spectator area appears at a show court, whether the mezzanine is counted, and how much of the floor is called "court" versus "assembly."

For contrast: the same building as a warehouse, at 500 gross, is about 20 occupants. The conversion increases the design occupant load by roughly an order of magnitude. That is the intuition behind the Group S trigger, and it is why the argument "but we aren't changing the structure" does not answer it.

Action: ask the architect to produce a preliminary code-analysis sheet — occupancy classifications, occupant loads by space, and the resulting risk category — before the structural evaluation is scoped. It is inexpensive, it determines which of two performance objectives the engineer is working to, and finding out late means re-running the analysis.

Oakland's local layer

Oakland has mandatory seismic retrofit programs, but they do not appear to reach this building:

• Mandatory Soft Story Retrofit Program, ordinance No. 13516, adopted 22 January 2019 — multi-unit, wood-framed residential buildings permitted before 1 January 1991. Design per CEBC Appendix Chapter A4 or ASCE 41. Not applicable to a concrete tilt-up. — SGH, "Understanding the City of Oakland's Soft Story Seismic Retrofit Ordinance"; RDH, "Oakland Mandatory Soft Story Ordinance" (retrieved 27 Aug 2026)
• Unreinforced masonry buildings, Oakland Municipal Code Chapter 15.28 — applies to buildings "built of unreinforced masonry walls." A concrete tilt-up is not URM. — OMC Ch. 15.28 (retrieved 27 Aug 2026)
• No Oakland tilt-up ordinance found. Searching Oakland's municipal code and the seismic-ordinance literature surfaced no concrete tilt-up retrofit program in Oakland. Nationally, tilt-up ordinances are rare; STRUCTURE notes Fremont as "an earlier adopter" and that "there is no statewide retrofit ordinance." — Dal Pino, STRUCTURE, 31 March 2025 (cited above)
• Oakland's CEBC amendments are a short list, and none of them touch the provisions in this section. OMC Ch. 15.04, Part 10 (§§ 15.04.3.10100–10165) adds CEBC § 301.4; amends §§ 403.1, 403.1.1, 404.1.1, 405, 407.1, 410.4.1, 410.4.2 and 410.5; deletes §§ 405.2–405.4, 407.3 and 410.6–410.9; adds § 407.4.2; and adopts Appendix Chapter A4 (the soft-story retrofit chapter). Sections 403 through 410 are the CEBC's repairs provisions. There is no Oakland amendment to § 304 or § 506. — OMC Ch. 15.04, Part 10 (section list read 27 Aug 2026; the individual amendment texts are behind a subscription — see § 8, item 4)

Net: the obligation here appears to come from the state code's change-of-occupancy provision, not from an Oakland ordinance. The diligence tracker's concern text — "Oakland may compel it on change of use" — is directionally right and mislocated: the compulsion is in the CEBC, and Oakland enforces it.

What could change this answer

Be honest about the ways the finding could move:

1. The building may not be Group S at all. This is the big one, and it is § 6.1. If the occupancy of record is Group F (factory industrial) rather than Group S (storage), the special clause never fires and the analysis falls back to the risk-category test. Unresolved.
2. The performance compliance method (CEBC Chapter 13). It does apply to changes of occupancy, but its § 1304.1.1 requires the owner to have a structural analysis demonstrating the completed building "is capable of resisting the loads specified in Chapter 16" of the building code — which is not obviously a cheaper structural outcome than § 304.3.2. Not an escape hatch on the face of it. — CEBC 2025 Chapter 13 (retrieved 27 Aug 2026)
3. Oakland's own interpretation. Plan check determines whether the trigger applies and which edition of ASCE 41 governs. A pre-application meeting is the cheapest way to find out, and it should happen in diligence, not after close.
4. The building may already have been retrofitted. Tilt-up anchorage retrofits have been common in the Bay Area for thirty years. If a prior owner did one and there is a permit record, both the finding and the cost change substantially. This is a specific, answerable question for the Oakland permit file.

7. What this means for SquashDrive

How to read a structural engineer's proposal against this framework

A proposal that does not answer these is not yet a proposal:

The questions to ask before signing

1. Which edition of ASCE 41 does the City of Oakland require for this project, and have you confirmed that with them rather than assumed it?
2. What is the building's existing occupancy classification of record — Group S (storage) or Group F (factory industrial)? What document did you get that from? (See § 6.1: this determines whether the trigger fires at all.)
3. Do you agree that CEBC § 506.5.3 / § 1006.3 is triggered by a Group S to assembly/educational change of occupancy for this building? If not, why not?
4. Assuming Risk Category II is confirmed, do you agree Exception 4 puts us on § 304.3.2 reduced criteria rather than § 304.3.1?
5. What will it cost to report results at both § 304.3.2 and § 304.3.1, so the board can see the price of a higher objective?
6. What tier are you proposing for (a) our planning purposes and (b) permit submission — and are those the same engagement or two?
7. What data collection are you assuming? What would it cost to move from a defaults-based knowledge factor to a validated one, and what is your estimate of the retrofit-quantity difference?
8. Is the mezzanine in scope? Priced as evaluation of an existing structure, or as new design?
9. Are geologic site hazards in scope? The parcel is in a CGS Zone of Required Investigation with Very High liquefaction susceptibility. How do you intend to coordinate with the geotechnical engineer, and what happens to the foundations and the slab if the borings confirm the mapping?
10. Are nonstructural components in scope — ceilings, lighting and equipment over the courts?
11. What is your assumption about existing wall anchorage, and what site investigation would confirm it?
12. Have you checked the Oakland permit file for a prior anchorage retrofit?
13. What do new or enlarged openings in the tilt-up panels do to the analysis, and when do you need the architect's opening layout?
14. What is your fee for plan-check response, and what is your experience with Oakland plan check specifically?
15. Who signs and stamps, and are they a California-licensed Structural Engineer (SE) rather than only a Civil (PE)?

What the deliverable should contain

Two published reports show what good looks like, and both are worth handing to a prospective engineer as a reference standard for the deliverable.

IDA Structural Engineers, Kensington Public Safety Building (5 Sept 2019 — a Tier 1 and Tier 2 evaluation with conceptual retrofit design) is structured as: introduction and evaluation basis table (risk category, performance objective, hazard level, level of seismicity, soil type, site class, building type) → performance objective explained in prose → site description → building description including prior renovations → geotechnical information → site observation notes → available documents reviewed → code assessment → numbered Tier 1 deficiencies → Tier 2 analysis of each → appendices with the checklists and calculations.

UC Berkeley / Degenkolb Engineers, Central Heating Plant (27 Dec 2018 — a Tier 1 evaluation on a standardized institutional form) leads with a one-line rating, then building data (ASCE 41 model building type per direction, dimensions, year of construction and code year), a cost range to retrofit field, building description, structural system, condition, date of site visit and who performed it, limitations of the walk-through, site information with the basis for every seismic parameter, geologic hazards with their basis, and a summary of previous ratings.

— IDA report; UC Berkeley / Degenkolb Tier 1 evaluation (both retrieved 27 Aug 2026)

Things to insist on, drawn from those two:

• The basis for every input, not just the value. Berkeley's form gives a "Basis:" line for site class, every geologic hazard, and every spectral acceleration. Where the basis is "assumed," you have found a place where money can buy certainty.
• Limitations of the walk-through, stated. What the engineer could not see.
• Deficiencies numbered and individually described, not a narrative.
• A retrofit cost range, even a rough one, in the evaluation deliverable.
• A list of the documents actually reviewed. If it is short, § 4 applies.

How this flows into cost

Three separate lines, and it is worth keeping them separate in the model:

1. Evaluation fee — engineering. The current diligence line is $5,000.
2. Retrofit design fee — engineering, and a different engagement.
3. Retrofit construction — the actual anchors, ties, nailing and any new lateral elements. This is the number the board cares about, and it does not exist until at least the evaluation is done.

And a fourth, which the parcel record has now put on the table and which does not belong to the structural engineer at all: liquefaction mitigation, if the borings confirm the mapping. That is a geotechnical-led scope, it is ground work under the building's floor, and nothing in this brief bounds it.

On magnitude: the honest answer is that no defensible per-square-foot number for a tilt-up wall-anchorage retrofit was found in public sources and this brief will not invent one. The figures that circulate for "seismic retrofit" of concrete buildings (on the order of $40–$150/sf) are for non-ductile concrete frame retrofits — a far heavier scope than tilt-up anchorage — and quoting them here would mislead. [unverified — see § 8, item 6.] Get a range from the evaluating engineer, and treat their range as the input to the cost model's Seismic line.

What can be said directionally: tilt-up anchorage is at the cheap end of seismic retrofits — repetitive, off-the-shelf hardware, no new foundations, work concentrated at the roof-to-wall interface. The scenario that is not cheap is one where the evaluation finds in-plane wall or diaphragm deficiencies requiring new lateral elements. That is what more data collection and a higher tier are insurance against.

Tie-in to the diligence tracker

The tracker's Structural Assessment scope (struct, Phase 1, $5,000, planned days 14–55) already carries the right three concerns. This brief suggests five edits, for the hub to make — the last one is against the Geotech scope, not the structural one, and is arguably the most urgent of the five:

1. Reword the first concern. "Oakland may compel it on change of use" → the California Existing Building Code compels a seismic compliance check on a Group S change of occupancy (CEBC §§ 506.5.3 / 1006.3); Oakland enforces it. Condition it on the occupancy classification per § 6.1 rather than on Oakland's discretion — that is where the uncertainty actually lives.
2. Split the budget line. $5,000 is plausible for a Tier 1 screening plus a findings memo. It is not plausible for the Tier 3 evaluation the code path in § 6 points to, nor for retrofit design. Carry the compliance-level evaluation as a Phase 2 contingent line so the board sees it before it arrives.
3. Add a document-recovery task, and put the Certificate of Occupancy first on it. Pull the Oakland permit file: the C of O and the last permitted use (§ 6.1), original permit drawings, structural calculations, any prior anchorage retrofit, roof permits. Low cost, direct effect on the knowledge factor (§ 4), it may answer the prior-retrofit question outright, and the C of O decides whether § 6's finding applies at all. This is the highest-value item in the whole diligence scope relative to its cost. § 6.2 has the channels, fees and gotchas — it is a near-zero-dollar task with a long calendar tail, so it should start in week 1 and be tracked as a task, not folded into a vendor scope. Add the C of O and the permit history to the PSA's seller-delivery list at the same time.
4. Add a pre-close code question. A pre-application or plan-check meeting with Oakland confirming (a) the change-of-occupancy trigger, (b) which ASCE 41 edition applies, (c) whether Exception 4 / § 304.3.2 is accepted, (d) whether the project clears the PRC § 2693(d)(2) 50% tests. All four are free to ask and expensive to guess wrong.
5. Re-grade and re-scope the Geotech line. geo1 (Phase 1, $2,500) carries the concern "Liquefaction susceptibility unconfirmed for this block" at medium severity. The parcel record confirms it: CGS Zone of Required Investigation = YES, susceptibility = Very High. That concern should move to high and be reworded from "unconfirmed" to confirmed-by-mapping-pending-borings. More importantly, $2,500 buys a preliminary soils opinion; it does not buy a Seismic Hazards Mapping Act geotechnical report — a statutory deliverable, stamped by a registered civil engineer or certified engineering geologist, containing a site-specific hazard evaluation and proposed mitigation, reviewed by the City and forwarded to the State Geologist. That report is a precondition to project approval, so it is not optional and it is not deferrable to Phase 2. The "3 borings min." next-action is the right instinct; the RFP should name the Act.

And one sequencing note for the timeline: the architect's preliminary code analysis (occupancy classifications, occupant loads, risk category) is a prerequisite to scoping the structural evaluation properly, and it currently has no milestone of its own.

8. What we know vs. what we don't

Verified against the sources named

Every item below was read in the source named, on 27 August 2026.

Not verified — do not rely on these without confirmation

The biggest one, before the numbered list: the building's existing occupancy classification — Group S or Group F. Section 6's entire finding is conditioned on it. The project's own documents say "warehouse" in one place and "light-industrial building" in another; neither is a code classification, and no Certificate of Occupancy or permit record has been read. If the classification of record is Group F and the risk category stays at II, § 506.5.3 does not fire at all. See the matrix in § 6.1. Answerable from the Oakland permit file, in the same request as item 8 below. Related and also unresolved: whether California amends CBC § 311, whose text was read in the model-code rendering rather than the California one.

1. Which edition of ASCE 41 the 2025 CEBC actually incarnates for this project. The referenced-standards listing surfaced ASCE/SEI 41-2013, 41-2017 and 41-2023, with different section mappings, and some of the 41-23 references appear tied to OSHPD (healthcare) provisions. Los Angeles has adopted 41-23 effective 1 Jan 2026 for buildings in its jurisdiction, but Oakland's position was not confirmed. This is the first question to put to Oakland plan check. Searched: CEBC 2025 Chapter 16 referenced standards; DGS 2025 Title 24 change pages; the ICC code viewer (HTTP 403 to automated retrieval).
2. Whether CEBC § 304.3.2 requires a Tier 3 procedure, or permits a lower tier. § 304.3.1 says "Tier 3" in terms. The § 304.3.2 text as retrieved names the performance objective without naming a tier; LADBS's bulletin reads Tier 3 into it for Los Angeles. Whether Oakland reads it the same way is unconfirmed, and it is a meaningful fee difference.
3. S_DS at 105 2nd St. Not computed. Exception 2 to § 506.5.3 turns on S_DS < 0.33, and Oakland's seismicity makes that exception almost certainly unavailable — but "almost certainly" is not a number. The engineer will pull it from the ASCE Hazard Tool (ascehazardtool.org) or a site-specific study, along with site class, which requires a geotechnical report.
4. The full text of Oakland's CEBC amendments, and their codification date. The complete list of amended sections was read (§§ 15.04.3.10100–15.04.3.10165), and it contains nothing touching CEBC § 304 or § 506 — which is what the § 6 finding turns on. But the individual amendment texts sit behind an eLaws subscription and the Municode viewer is a JavaScript application that would not render, so the texts themselves were not read; nor was it confirmed whether the published codification reflects the 2025 adoption (ordinance File #26-0024) or still the 2022 one. Confirm directly with Oakland Building Services. Note also that Oakland adopts Appendix Chapter A4, so an Appendix A chapter is live in this jurisdiction — relevant because § 304.3.2 lists "the applicable Appendix A chapter" as one of its three compliance routes, and A4 is the wood soft-story chapter, not one for tilt-up.
5. The occupancy classification of the tutoring program (Group E vs Group B), and the resulting occupant load and risk category. The § 6 arithmetic is illustrative, built on this project's own test-fit program shape, not a code analysis. An architect must produce the real one. The margin to the Risk Category III threshold appeared to be roughly 20%, which is not comfortable.
6. Any cost figure for a tilt-up anchorage retrofit. No credible public per-square-foot range was found. The $40–$150/sf figures in circulation are for non-ductile concrete frame retrofits and are not applicable. Searched: FEMA and ATC publications, STRUCTURE, contractor and engineering-firm pages. The Berkeley Tier 1 form has a "COST RANGE TO RETROFIT" field, which is why § 7 asks for one in the deliverable.
7. FEMA P-1026 read in the original. The FEMA-hosted PDF returned HTTP 403 to automated retrieval; the roof-acceleration amplification figures (≈1.5× at edges, 4–5× at diaphragm centre; 3–4× ground acceleration at roof level in Northridge) come from secondary summaries. Directionally reliable, not design values.
8. Whether 105 2nd St has already had an anchorage retrofit. Unknown, and materially affects both scope and cost. Answerable from the Oakland permit file — and because the Bay Area's voluntary tilt-up retrofits clustered after 1989 and 1994, this one may well fall inside the post-1987 window that Oakland's free online permit search covers (§ 6.2). Not yet run: the portal was in scheduled maintenance on 27 Aug 2026.
9. The building's wall thickness, roof framing and diaphragm type. The construction year (1969) now comes from Oakland's Land Information Report, but everything else in § 5 describes what is typical of the class, not what was verified about this building. Note also that a planning-record construction date is not the same as a permit date, and buildings get re-roofed, added to and altered.
10. Whether the unpermitted mezzanine can be legalized at all, and on what structural terms. Out of scope here; it is already a logged high-severity diligence concern.
11. Whether the 2024 model IEBC Group S/U language is identical to California's. The ICC code viewer returned HTTP 403; the inference rests on LADBS's public comment characterizing the "current language in 2024 IEBC." The California text was read directly and is what governs, so this does not affect the finding.
12. Anything about insurance. Earthquake insurance availability and pricing for a retrofitted versus unretrofitted tilt-up, and whether a lender or insurer imposes its own seismic standard (e.g. a probable maximum loss study), was not researched and could independently drive the objective decision.
13. Whether Oakland treats this project as a "project" under PRC § 2693(d). The 50%-of-value and 50%-of-floor-area tests look comfortably exceeded by a whole-building conversion, which would make the Seismic Hazards Mapping Act geotechnical report mandatory — but the valuation basis (depreciated structure value? assessed improvement value? replacement cost?) and how Oakland measures the floor-area limb were not researched. Confirm with the City.
14. What the site actually does under shaking. "Very High" liquefaction susceptibility is a regional screening classification, not a site-specific finding. No borings, no site class, no ground-motion parameters. Nothing in this brief estimates a mitigation scope or cost, and nothing should be read as doing so.
15. The Oakland Cultural Heritage Survey rating "F3." The letter-plus-number scheme is documented (letters for individual importance, numbers for district status), but the meaning of an "F" letter was not pinned down; Oakland's rating page returned HTTP 403 and the survey-system appendix would not render. The material conclusion does not depend on it — the same report says Local Register NO, PDHP NO, Landmark NO and Heritage Property NO, so the building is not a qualified historical building and the California Historical Building Code path is unavailable.
16. Zoning and the land-use permit path. The parcel is zoned D-DT-C per the Land Information Report, and Oakland's D-DT chapter appears to contemplate Community Education / Community Assembly / Recreational Assembly Civic Activities — but the chapter itself returned HTTP 403 to retrieval and the activity classification for a nonprofit squash-and-tutoring facility is a planning determination that was not made. This has no bearing on § 506.5.3; it is flagged because the brief previously speculated the parcel might be industrially zoned, and it is not.

Glossary

A board member should be able to follow "we're doing a Tier 1 screening against BPOE" without stopping the meeting.

Sources

All retrieved 27 August 2026.

ASCE — the standard itself

• ASCE store, Seismic Evaluation and Retrofit of Existing Buildings (41-17) — the link supplied for this brief
• ASCE store, Seismic Evaluation and Retrofit of Existing Buildings (41-23) — the current edition
• ASCE Library, ASCE/SEI 41-23 canonical record (bot-gated; the store page above carries the same details)
• ASCE, ASCE 41 codes and standards page
• ASCE, Performance-Based Principles to withstand Earthquakes: ASCE 41-23 (ASCE-published introduction)
• ASCE, "ASCE 41-23 provides significant updates…", Civil Engineering Source, 1 Dec 2023
• ASCE, ASCE/SEI 41-23 Tier 1 and Tier 2 Updates course listing
• ASCE Hazard Tool

California code (public law)

• California Existing Building Code 2025, Ch. 3 — Provisions for All Compliance Methods (§§ 301, 304)
• CEBC 2025, Ch. 5 — Prescriptive Compliance Method (§ 506.5.3)
• CEBC 2025, Ch. 10 — Change of Occupancy (§ 1006.3)
• CEBC 2025, Ch. 13 — Performance Compliance Methods
• CEBC 2025, Ch. 16 — Referenced Standards
• CEBC 2022, Ch. 5 — Prescriptive Compliance Method (§ 506.5.3)
• 2021 IEBC § 506 Change of Occupancy
• California Building Code 2025, Ch. 3 — Occupancy Classification and Use
• CBC 2025, Ch. 10 — Means of Egress (Table 1004.5)
• CBC 2025, Ch. 16 — Structural Design (Table 1604.5)
• DGS Building Standards Commission — 2025 Title 24 California Code Changes
• Shahen Akelyan (LADBS), public comment on 2025 CEBC § 506.5.3, 9 Oct 2024

Jurisdictional guidance

• LADBS Information Bulletin P/BC 2026-148, Procedures for the Application of ASCE 41-23 to Existing Buildings (eff. 1 Jan 2026, rev. 3 Apr 2026)
• City of Oakland — Adoption of 2025 California Building Codes
• Oakland File #26-0024 — Local Amendments to 2025 California Model Building Construction Codes
• Oakland Municipal Code Ch. 15.04, Part 10 — California Existing Building Code amendments
• Oakland Municipal Code Ch. 15.28 — Unreinforced Masonry Buildings
• SGH, "Understanding the City of Oakland's Soft Story Seismic Retrofit Ordinance"
• RDH, "Oakland Mandatory Soft Story Ordinance"
• Degenkolb Engineers, "ASCE 41-17 Implementation", memo to Oregon Seismic Rehabilitation Grant Program, 13 July 2018

Tilt-up and rigid wall–flexible diaphragm buildings

• FEMA P-1026, Seismic Design of Rigid Wall–Flexible Diaphragm Buildings: An Alternative Procedure, 2nd ed., Oct 2021 — ATC listing
• John W. Lawson, "Revisiting Earthquake Lessons: Wall Anchorage to Flexible Diaphragms", SEAOC, 1 Aug 2018
• John Dal Pino, "Seismic Retrofit Ordinances Part 3: Concrete Tilt-up & Wood Soft-Story", STRUCTURE, 31 Mar 2025
• SGH, "What Are Rigid Wall Flexible Diaphragm Buildings?"

Worked examples of ASCE 41 reports

• IDA Structural Engineers, Conceptual Retrofit Design based on ASCE 41-17 Tier 1 and 2 Seismic Evaluation — Kensington Public Safety Building, 5 Sept 2019
• UC Berkeley / Degenkolb Engineers, ASCE 41-17 Tier 1 Seismic Evaluation — Central Heating Plant, 27 Dec 2018

Research and secondary technical sources

• M.S. Speicher, Z. Zhang, B.W. Schafer, "Application of ASCE 41 to a two-story CFS building", CFSRC Colloquium, Oct 2020
• ProtaStructure, Design Guide: Assessment & PBD to ASCE/SEI 41, May 2025

Seismic hazard, and the site

• USGS, HayWired Earthquake Scenario, Fact Sheet 2018-3016
• USGS, HayWired Scenario program page
• Public Resources Code § 2693 — Seismic Hazards Mapping Act definitions, incl. the 50% "project" exclusion
• Public Resources Code § 2694 — seller disclosure of a seismic hazard zone
• Public Resources Code § 2697 — geotechnical report required prior to project approval
• CGS Special Publication 117A, Guidelines for Evaluating and Mitigating Seismic Hazards in California (adopted 1997, revised and re-adopted 2008) — quotes 14 CCR § 3724 and reprints the Act
• CGS, Special Publication 117A landing page
• City of Oakland, Land Information Report for APN 001 016501600 (105 2nd St) — supplied to this project, not a public URL
• City of Oakland, Planning & Building Records Requests — records channels, 3-R fees, plan-viewing process, Records Unit contact
• Oakland Online Permit Center (Accela Citizen Access) — free permit-record search, records after 1987
• City of Oakland public records portal (NextRequest) — Public Records Act requests and the archive of prior responses
• City of Oakland, Application for Re-issuance of a Certificate of Occupancy, April 2024
• City of Oakland, Zoning Permit Fees Schedule (rev. 21 Feb 2023) — defines the Technology Enhancement / Records Management fee as a percentage of the other fixed fees
• Oakland Planning Code Ch. 17.101K — D-DT Downtown District Zones Regulations
• City of Oakland, Historical and Architectural Rating Systems (bot-gated; see § 8, item 15)

Prepared as internal research for SquashDrive. Not engineering advice and not a substitute for ASCE/SEI 41, which is a copyrighted standard sold by ASCE and is not reproduced here. No structural conclusion in this document has been reviewed by a licensed engineer. Confirm every code citation, every trigger and every performance objective with a California-licensed Structural Engineer and with City of Oakland Building Services before acting.