Structural drawings
Framing plans, foundation plans and shear-wall schedules keyed to your architectural set — sheet-numbered and plan-check ready.
Home addition engineering · California
Add the Room. Engineered Plans, Permit Package Included, One Fixed Price.
Foundations, framing and lateral design for room additions and second stories, tied correctly into your existing house and delivered as a permit-ready package.
What are you adding?
60 seconds · Free · No obligation
Step 1 of 4
- California PE-licensed engineers (CA & NV)
- Fixed-price quote — no hourly billing
- No commitment until you accept
- Corrections included per proposal
What are you adding?
60 seconds · Free · No obligation
Step 1 of 4
California PE-licensed engineers
Fixed-price proposals
Permit-ready documents
Corrections handled
How it works
From this page to permit-ready plans.
- 1
Today — about a minute
Answer a few questions & tell us where to send the quote
Plans, photos, sketches or a permit letter. Don't have everything? Send what you've got.
- 2
Within 1 business day
Free scope review → fixed-price proposal
A defined scope, one price and a stated turnaround. Your quote stays valid for 30 days.
- 3
After you accept online
Engineering starts — track it live
E-sign, pay the deposit by card or ACH, and watch status through delivery on your dashboard.
Your quote
One fixed price. In writing. Before you commit.
- Free scope review — you pay nothing to find out what your project needs
- A fixed price for a defined scope; additional work is only ever quoted, never surprise-billed
- Your quote stays valid for 30 days while you line up your contractor
- Plan-check correction rounds included per the proposal
Where additions get stuck in plan check
- No design for how new framing ties into the existing house
- Missing lateral analysis where new walls change the bracing
- Foundations that don't address the existing footing at the connection line
- Second-story loads with no path through the first floor
- Calcs that don't match the drawings
Sound familiar? Answer 3 questions and get your fixed-price quote →
Deliverables
What you receive
A complete, engineer-reviewed structural package — the same documents a full-service firm produces, delivered through your project dashboard.
What you receive
Structural calculations
Gravity and lateral calculations that match the drawings, member by member, so plan checkers can follow the load path.
Details & connections
Beam-to-post, holdown, footing and connection details your framer can build from — no guesswork on site.
Plus permit-correction responses and revisions through the same project. Get your quote →
Pricing, honestly
What actually drives the price
No two projects price the same — these are the factors our engineers scope. You get one fixed number after a free review, not an hourly meter.
Footprint and stories
Square footage drives framing; a second story adds load-path and lateral work through the existing house.
Existing structure
Tying into a 1950s raised floor is different from a modern slab — verification is part of the design.
Openings between old and new
Big pass-throughs between the house and addition mean beams and posts at the connection line.
Roof complexity
Matching existing rooflines and vaulted spaces adds members and details.
The risk is on us: free scope review, fixed price, and no commitment until you accept.
Get My QuoteWhy JAT
Built like software, reviewed like a firm.
The engineering is the same discipline you'd expect from any licensed structural firm. The way you order it, track it and receive it is not.
Comparison with a traditional engineering engagement
| The usual way | With JAT Engineering | |
|---|---|---|
| Getting a quote | Phone tag, site visit scheduling, waiting weeks for a proposal | Upload plans or photos online; defined scope and fixed price after review |
| Knowing where things stand | Emails and voicemails | One status per project, visible in your dashboard 24/7 |
| Documents & revisions | PDF attachments scattered across inboxes | Versioned drawings, calcs and permit comments that stay with the project |
| Plan-check corrections | A new conversation and often a new invoice | Submitted back through the same project — rounds included per proposal |
| Repeat projects | Start from scratch every time | Duplicate a past project or use a template — under two minutes |
| Paying | Paper invoices and checks | Card or ACH online; deposit to start, balance before final release |
Before you ask
What does addition engineering cost?+
Quoted per project after a free scope review — a defined scope at one fixed price, with correction rounds included. No commitment until you accept.
Can you start before my architectural plans are final?+
Yes — we can scope from preliminary plans and start once the layout is stable. If the design moves later, revisions run through the same project so nothing gets lost.
Does a second story mean foundation work?+
Often some. New loads travel down through existing walls and footings; part of the design is checking what the existing structure can take and detailing upgrades only where needed.
Will you handle the city's comments?+
Yes. Submit the correction letter through your project and we respond with revised, engineer-reviewed documents. Rounds are included per your proposal.
Add the Room. Engineered Plans, Permit Package Included, One Fixed Price.
Three questions, a free scope review, and a fixed-price quote — usually within one business day.
No commitment required to submit a project for review.