Every Casita needs a permit, and every permit needs a site-specific, PE-stamped foundation plan. That's all we do — Casita foundations, feasibility, and certifications — engineered fast and formatted the way building departments expect.
Four services, one specialty. Each links to our full engineering hub at BoxablFoundations.com, where you can order directly.
PE-stamped, permit-ready plans engineered for your soil, frost depth, wind, and seismic conditions. Slab, crawlspace, or pier — with the anchorage detailing plan reviewers check first.
Compare packages →Before you buy land or a unit: zoning, setbacks, utilities, soil, and delivery access reviewed for your exact parcel, with a written go / no-go recommendation.
Check my site →PE-stamped certification letters for insurance, refinancing, or resale — including HUD-compliant letters for manufactured-home financing pathways.
Get certified →Setting multiple Casitas? One engineering relationship: partner rates, priority queue, and jurisdiction-ready plan packages across all 50 states.
Partner with us →From the original Casita to Boxabl's 2026 Phase 2 catalog — each model puts different demands on its foundation. Pick yours for the full engineering breakdown.
| Model | Size | Foundation reality | |
|---|---|---|---|
| Casita Studio | 361 sq ft | Single module — slab, crawlspace, or piers; wind anchorage governs | Guide → |
| 1-Bed Casita | 722 sq ft | Multi-module — foundation layout must align both modules precisely | Guide → |
| 2-Bed Casita | 722 sq ft | 13,000 lbs, rated 140 mph wind / SDC D — anchorage engineered to match | Guide → |
| Baby Box (RV) | 120 sq ft | No foundation by default — pad, leveling & tie-downs; convertible to real property | Guide → |
| Phase 2 Catalog | 24 configs | ADUs to 3-story garden apartments — multi-module & multi-story engineering | Guide → |
A general structural engineer can design you a fine foundation — after learning the Casita's folding SIP panel system, its ICC-ES ESR-4725 evaluation report, its module connection tolerances, and how your particular building department wants all of it presented. You pay for that learning curve in fees and review cycles. We've already climbed it, hundreds of questions deep, across dozens of jurisdictions — which is why our plans start at $749 and clear review instead of bouncing. Our permitting research is published openly at BoxablFoundations.com, including requirements for all 50 states.
The four questions every Casita owner asks first.
We design the site-specific, code-compliant foundation your Casita sits on — sized for your soil, frost, wind, and seismic conditions — and stamp the plans your building department needs to issue a permit. We also evaluate lots before purchase and certify existing foundations for lenders and insurers.
Plans from $749 (up to $1,999 for 1–3 day expedited delivery). Site feasibility with a 30-minute PE call is $299. The foundation itself typically runs $5,000–$25,000 built, depending on type and region — estimate your full project here.
Our principal engineer is PE-licensed in 39 states, with partner engineers covering the rest — every U.S. project can get permit-ready plans. Twelve states qualify for expedited 1–3 day turnaround.
Yes — all 24 configurations in Boxabl's 2026 catalog, from backyard ADUs to three-story garden apartments, including volume engineering for developers and installers.
Project questions, odd lots, plan-review pushback, developer volume — we answer all of it.
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