Additions · San Diego
Does a Two-Story Addition Follow Different Permit Rules Than a Single-Story One in San Diego?
Yes. The city’s own prescriptive addition bulletin stops at one story, so a second-story addition is reviewed as an engineered structure, not a lookup-table one. Here is what changes, what stays the same, and where a second floor adds a step the single-story version of your project never had.
Key takeaways
- San Diego’s main prescriptive addition bulletin, Information Bulletin 140, applies only to additions and remodels that do not rise above one story. A second-story addition falls outside it by definition.
- Outside that scope, your framing, foundation and shear design must be shown through project-specific structural calculations rather than the bulletin’s prescriptive span tables.
- Several requirements apply no matter how many stories you add: the same intake forms, the same stormwater thresholds, and the same 45-year historical review trigger.
- A HERS rating (home energy verification testing) can be required on an addition independent of story count — the city ties it to added floor area and duct work, not building height.
- Items like truss calculations and foundations on fill or expansive soil already require a licensed engineer or architect’s stamp under Information Bulletin 140, even on a single-story project — a second story simply extends that requirement to the whole structural system.
In this guide
1. The short answer
Yes, and the difference starts before a single wall is framed. San Diego’s Development Services Department publishes Information Bulletin 140, “Residential Addition/Remodel,” as the city’s prescriptive design path for single-family and duplex additions and remodels — but the bulletin states its own scope limit: it covers projects that “do not exceed one story above grade or above a crawl space.” A second-story addition is not an edge case the bulletin handles loosely. It is outside the bulletin entirely.
That matters because IB-140 is what lets a single-story addition skip custom engineering for ordinary framing. It supplies ready-made span tables for rafters, joists, headers and nailing schedules, built around standard Douglas fir-larch framing. A two-story project cannot borrow those tables, because the loads involved — what the lower floor and foundation now carry from the floor above — are project-specific.
2. Why one bulletin stops at one story
IB-140’s prescriptive tables (the bulletin numbers them Tables 1 through 8) exist for a narrow reason: they are pre-solved for one set of conditions — one-story wood-frame constructions, Douglas fir-larch #2 lumber, a 20 psf roof live load and a 40 psf floor live load. Change the number of stories and you change the load path for every beam, post and footing below the new floor. The bulletin’s own text reflects this: it tells applicants plainly that “project-specific plans must be submitted” and that the sample drawings are “a guide only.”
San Diego does publish a parallel track for taller or more complex residential construction, but it runs through full plan review rather than a published span table. In practice, that means your structural plans for a second-story addition must independently demonstrate compliance with the California Residential Code and the San Diego Municipal Code, the same two codes IB-140 cites as the baseline every addition must meet — just without the shortcut.
None of this means a two-story addition is unbuildable on a modest lot, or that it is dramatically slower at the counter. It means the design phase looks different: your structural engineer (not a prescriptive table) is doing the work of proving the framing, connections and foundation hold up, and that work has to happen before plans go in, not during plan check.
3. Prescriptive tables vs. engineered design
The clearest way to see the difference is side by side. This is not a cost comparison — the city does not publish engineering fees — it is a comparison of which document does the proving.
| Element | Single-story addition (within IB-140) | Two-story addition (outside IB-140) |
|---|---|---|
| Framing spans & headers | Read from IB-140’s prescriptive Tables 1–8 for standard lumber and loads | Calculated project-by-project by a licensed engineer or architect |
| Foundation & footings | Sized from the bulletin’s foundation plan guidance for typical conditions | Sized to carry the accumulated load from the floor above; soils conditions matter more |
| Lateral (shear) design | Standard wall bracing per the bulletin’s framing guidance | Project-specific shear wall and connection design, reviewed against submitted calculations |
| Prefabricated trusses | Calculations still require a stamp from a licensed architect or civil engineer | Same stamp requirement, applied across a larger, more complex roof and floor system |
Two items on this table — truss calculations and anything on fill or expansive soil — already need a licensed professional’s stamp under IB-140, regardless of story count. A two-story addition does not introduce the idea of licensed sign-off; it widens where that sign-off applies, from a few specific items to the whole structural system.
4. What stays the same at any story count
It is easy to assume a two-story addition resets every rule. It does not. Several requirements in IB-140 apply to any qualifying addition or remodel project the city processes, and nothing in the bulletin ties them to a story limit.
- Intake forms. The Project Contacts Information Form (DS-345) is required on every project; the Owner-Builder Verification Form (DS-3042) applies whenever the owner acts as their own general contractor.
- Water meter data. A Water Meter Data Card (DS-16) is only required when new plumbing fixtures are added — relocating existing fixtures does not trigger it, at one story or two.
- Stormwater review. The Stormwater Requirements Applicability Checklist (DS-560) is required on every plan submittal, and the city’s ground-disturbance thresholds for a fuller Water Pollution Control Plan are measured in square feet of disturbed ground, not building height.
- The 45-year historical review trigger. If a site has a structure 45 years or older and the project includes exterior work beyond in-kind roof repair, a historical resources review applies before a permit can issue — a rule tied to the age of the existing structure, not the height of what’s being added.
| Form or review | When it applies |
|---|---|
| Project Contacts Form (DS-345) | Every addition/remodel submittal |
| Owner-Builder Verification (DS-3042) | Only if the owner is acting as general contractor |
| Water Meter Data Card (DS-16) | Only if new plumbing fixtures are added |
| Stormwater Checklist (DS-560) | Every plan submittal, any project size |
5. Where a HERS rating enters the picture
A Home Energy Rating System (HERS) verification is a separate layer from the structural story-count question, and it can apply to a single-story project just as easily as a two-story one. HERS is a California Energy Commission program: CEC-approved providers certify and oversee individual HERS raters, who field-verify that specific energy measures were actually installed and perform diagnostic testing such as duct leakage testing.
The city’s own fee bulletin for mechanical, electrical and plumbing permits lists HERS rating as a required submittal item for several residential scopes, including new construction, major HVAC system changes, additions exceeding 1,000 square feet of floor area, and projects adding more than 40 feet of new ductwork. None of those triggers is about how many stories the addition has — they are about floor area and mechanical scope. A compact two-story addition under 1,000 square feet with no major duct work may not trigger it; a large single-story addition well past that threshold can.
| Project condition | HERS testing applies? |
|---|---|
| New residential construction | Yes |
| Addition exceeding 1,000 sq ft of floor area | Yes |
| More than 40 ft of new ductwork added | Yes |
| Major HVAC system replacement | Yes |
| Smaller addition, no major HVAC or duct work | Not automatically — confirm with your permit reviewer |
The CEC’s own guidance on this is direct: “properly permitted work will trigger any necessary HERS testing.” In practice, a rater will need access to the HVAC equipment, ducts, vents, thermostat and typically the electrical panel, and may need to reach the attic or crawlspace. Build this step into your schedule rather than discovering it at final inspection.
6. Planning around the engineered path
None of this changes what’s architecturally possible on most San Diego lots — it changes who has to sign the drawings and when that work has to happen. A single-story addition can sometimes move from sketch to submittal with a designer working from the bulletin’s own tables. A second story almost always means a structural engineer or architect is involved from the early design phase, producing calculations the city’s plan reviewers check against the submitted drawings rather than against a published table.
It’s also worth separating this from the zoning question. Setback, height-envelope and floor-area-ratio limits are a different layer of review entirely, and they apply to a second story the same way they’d apply to any structure reaching that height on your lot. If you haven’t confirmed your zone’s height envelope and FAR allowance yet, do that before your engineer starts calculating — it determines how much second floor you’re allowed to design for in the first place.
Items that are not specific to story count — the 45-year historical review trigger, the stormwater thresholds, soils reports on fill or expansive soil — still apply in parallel. A two-story addition on an older lot can end up carrying all of them at once: engineered structural design, a historical review, and a stormwater submittal, on top of the usual intake forms.
FAQ
Does a two-story addition cost more in city permit fees than a single-story one?
City plan check and inspection fees are based on the project’s calculated valuation, which scales with added square footage under the same fee schedule for any addition — the city does not publish a separate, higher fee rate specifically for a second story. A two-story addition typically does add more floor area than an equivalent single-story one on the same footprint, which raises the valuation the fees are based on. For the fee schedule itself, see Information Bulletin 501.
Can I use IB-140’s prescriptive tables for just the ground floor of a two-story addition?
No. IB-140 defines its scope by the completed project, not floor by floor — it applies to additions and remodels that do not exceed one story above grade overall. Once the finished structure includes a second story, the project as a whole falls outside the bulletin, and the lower floor’s framing and foundation need to be justified by the same engineered calculations that size the floor above it.
Does a two-story addition need a soils report?
It depends on the soil, not the story count. IB-140 requires a geotechnical investigation when a foundation sits on fill or expansive soil. On undisturbed native soil, the plans can instead carry a signed note to that effect from the owner, engineer or architect. A two-story addition puts more load on the same foundation, so where soil conditions are borderline, a reviewer is more likely to ask for documentation.
Does adding a second story trigger historical review differently than a single-story addition?
The trigger itself is the same either way: a site with a structure 45 years old or older that is undergoing exterior work beyond in-kind roof repair needs historical resources review before a permit can issue, per San Diego Municipal Code Section 143.0212. Story count doesn’t change whether the review applies — it only changes what the reviewer is looking at once it does.
Do I need a HERS rating for a two-story addition?
Only if your project trips one of the city’s listed triggers — new construction, an addition over 1,000 square feet of floor area, more than 40 feet of new ductwork, or a major HVAC replacement. Those triggers are tied to floor area and mechanical scope, not stories, so a two-story addition under those thresholds with minimal duct work isn’t automatically subject to it, and a large single-story addition past those thresholds is.
Does the city require a licensed architect specifically, or is an engineer enough?
IB-140 doesn’t mandate one project-wide architect of record. Where it calls for a stamp — on truss calculations, for example — it accepts either a California-licensed architect or a registered civil engineer. For a fully engineered two-story structural package, most San Diego projects use a structural engineer for the calculations, sometimes alongside an architect handling the overall design; confirm the specific stamp requirements for your submittal with your design professional and the city’s plan review staff.
Planning a second-story addition in San Diego?
Eco Home Builders coordinates design, engineering and permitting for additions across San Diego and Orange County, from a single-story bump-out to a full second-floor addition. Schedule a consultation to talk through what your lot and existing structure can actually support.
Sources
- City of San Diego Development Services, Information Bulletin 140, “Residential Addition/Remodel” (revised April 2026)
- City of San Diego Development Services, Information Bulletin 103, “Fee Schedule for Mechanical, Electrical, Plumbing/Gas Permits” (revised May 2026)
- City of San Diego Development Services, Information Bulletin 501, “Fee Schedule for Construction Permits-Structures” (revised August 2026)
- City of San Diego Development Services, Building Permit overview page
- California Energy Commission, Home Energy Rating System (HERS) Program overview
Cost and fee figures referenced here are drawn from published San Diego Development Services fee bulletins, not from an Eco Home Builders estimate or quote. Code requirements, bulletin figures and program details change; confirm current requirements with the City of San Diego Development Services Department and a licensed design professional before finalizing project plans.
