Boxabl Roof Options Explained (S5–S9): Gable, Hip, Shed, Low-Slope — and the Engineering Each One Needs

The Part of the Roof Boxabl Doesn't Ship

Every Casita leaves the factory with a flat SIP roof. The pitched profile you picture — gable, hip, shed — is a site-built option installed over that SIP roof after delivery. Boxabl publishes concept sheets for five roof options (S5–S9 in the Casita presentation sets), and every one of them contains the same box of text:

> "SITE-SPECIFIC DESIGN CRITERIA TO BE PROVIDED BY A LICENSED ENGINEER."

That's not boilerplate. It's the line between what the factory approval covers and what your building department will ask you to produce. Let's walk through the options, then the engineering.

The Five Roof Options

Pitches steeper than 5:12 require special design through Boxabl.

The Rules Hidden in the Notes

The truss sheets share a set of engineering rules that regularly surprise owners at plan review:

• •High wind: above 130 mph ultimate (Exposure B) or 110 mph (Exposure C), sheathing nailing tightens to 4"oc within 4 ft of the roof perimeter. Much of the coastal South trips this.
• •Snow: above 70 psf combined snow + roofing weight, thicker rated sheathing is required. Mountain and northern lots trip this routinely.
• •Seismic orientation: each truss layout has two orientations — and Orientation #2 is mandatory in Seismic Design Categories D and up. In most of California, western Nevada, the Wasatch Front, and western WA/OR, the layout isn't a preference; it's dictated.
• •Tile: clay and concrete tile roofing is prohibited in SDC D/E/F. High-seismic jurisdictions that love tile need an alternative.
• •Connections: eave clips (A35) are spaced "per engineer's specifications" — meaning someone has to run those numbers for your site. Bottom chords get 2x6 uplift bracing glued and screwed to the SIP roof.

Why Your State's Approval Doesn't Cover This

State modular programs — Texas TDLR, California HCD, Nevada's program — approve what's built in the factory under the insignia. The site-built roof is on-site construction under your local building permit:

• •Texas: TDLR requires a Texas-licensed engineer to design and seal "any unique on-site construction details" — a field-built truss roof is exactly that.
• •California: Boxabl's own S6 title block says the truss profile "has not yet been submitted" for state approval but "can be used if submitted along with custom, stand-alone, site-specific engineered Casita documents for local building dept. approval." Their words.
• •The same factory/site split applies across the modular-program states.

Who Provides What

Three parties produce the permit paperwork: Boxabl supplies the concept sheets with the unit. Your truss manufacturer's engineer designs and seals the trusses — but only to design criteria someone gives them. And a licensed site engineer provides those criteria plus everything the trusses touch: connection details, clip spacing, nailing schedules, orientation determination, sealed for your jurisdiction.

That middle-and-last piece — the site engineer scope — is what we productized. Our Roof Option Engineering Package covers it for the gable, hip, and shed options: $449 flat, PE-stamped, 2-day delivery, bundled naturally with foundation plans since both run off the same site data. Low-slope and parapet options (S5/S9) run through custom engineering — tapered-insulation drainage and parapet load paths deserve individual attention.

Bottom Line

Pick your roof by climate and taste — hip for hurricane country, gable for the classic look, shed for simplicity, low-slope to keep the factory profile. But whichever you pick, budget for the site engineering: the truss supplier needs criteria, the eave needs engineered connections, and your building department needs a stamp from your state. None of that ships in the box.

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Sheet references describe Boxabl's published Casita presentation documentation (models BXB-000002/BXB-000009) for educational purposes. We are not affiliated with Boxabl Inc. Nothing here is permit-ready engineering for any specific site — that's what the stamped package is for.