Official standard
CERTAFI+ Enhanced Building Standard
Tiny homes on wheels (THOW) · Version 1.0 · Effective January 1, 2026
A proprietary construction, documentation, and inspection standard for the certification of tiny homes on wheels, developed using selected provisions from national standards as reference material. CERTAFI+ uses a gated, stage-based workflow — plans must be approved before any inspection stage begins, and each stage must be approved before the next unlocks.
Important notice
CERTAFI is a private third-party documentation and inspection program. CERTAFI is not a government agency, not an authority having jurisdiction (AHJ), not a code enforcement body, and not a licensed engineering firm.
CERTAFI+ certification confirms review of submitted documentation against the CERTAFI+ Enhanced Building Standard only. It does not confirm compliance with NFPA, ANSI, NEC, IRC, or any external code, and does not replace permits, engineering, or local approvals.
Builders and owners remain solely responsible for complying with all applicable laws, codes, regulations, permit requirements, and jurisdiction-specific standards.
What's in the PDF
- Introduction, scope, and limitations of CERTAFI+ certification
- Pre-step (plans) gate and required uploads
- Stages 1–5: purpose, checklist requirements, photo and video expectations
- Technical requirements (framing, mechanical, insulation, life safety, loft, wind)
- CERTAFI+ enhanced requirements summary table
- Certification rules: sequencing, permanent locking, live video, outcomes
- Limitation of liability and disclaimer
- Contact and referenced standards list
Stage overview
The app mirrors this workflow: approve Plans first, then complete each stage in order. All five inspection stages (1–5) require a live video walkthrough captured within the CERTAFI platform in addition to GPS-tagged photos. Camera-roll uploads are flagged as manual submissions and may require additional review. Stage 5 (Final Inspection) approval triggers automatic certificate generation.
| Step | Name | Required media | Unlocks after |
|---|---|---|---|
| Pre-step | Plans Submission | Documents + specifications | Always available |
| Stage 1 | Trailer and Chassis | 7 photos + live video | Pre-step approved |
| Stage 2 | Framing and Dry-In | 8 photos + live video | Stage 1 approved |
| Stage 3 | Mechanical Rough-In | 6 photos + live video | Stage 2 approved |
| Stage 4 | Insulation and Thermal Performance | 4 photos + live video | Stage 3 approved |
| Stage 5 | Final Inspection | 14 photos + live video | Stage 4 approved |
Pre-step requirements
The pre-step (Plans Submission) is a hard gate — it must be approved before any inspection stage can begin. Stage 1 remains locked until the pre-step is approved. Builders must upload the following documents and provide unit specifications:
Required document uploads
- Trailer VIN documentation
- Floor plan and layout drawings with dimensions
- Electrical plan (panel location, circuits, and receptacle locations)
- Plumbing plan (supply lines, drain lines, and fixture locations)
Required project specifications
- Unit width and length
- Frame type and description
- Any structural or systems notes needed to interpret the plans
CERTAFI+ enhanced requirements
These are CERTAFI+ proprietary requirements that go beyond baseline reference material. Where a requirement below differs from any external publication, the CERTAFI+ requirement governs.
| Requirement | Description |
|---|---|
| 2×4 minimum wall framing | Minimum 2×4 studs required in all walls. 2×3 studs are not permitted. |
| 16″ on-center framing | Wall framing maximum 16″ on center. Roof framing maximum 16″ on center except where approved sheathing thickness permits otherwise. |
| R-13 floor and wall insulation | Floor and wall insulation minimum R-13. |
| R-19 ceiling / roof insulation | Ceiling or roof insulation minimum R-19. |
| PRV for high inlet pressure | Incoming water supply pressure exceeding 80 psi requires a pressure-reducing valve set to deliver not more than 80 psi. |
| Panel working clearance | Minimum 30 inches wide and 36 inches deep in front of the electrical panel. |
| AFCI protection | Arc-fault circuit interrupter protection on 120V, 15A and 20A branch circuits in living areas. |
| T&P relief discharge | Water heater T&P relief valve discharge pipe routed to a safe point of discharge, directed downward, and not capped. |
| Shore power service | ≤5 branch circuits: minimum 30A shore power. 6+ branch circuits: minimum 50A shore power. |
| Smoke alarms | Hard-wired with battery backup. ≤30 ft: min 1. >30 ft: min 2 interconnected. Each closed loft/sleeping area requires its own smoke alarm. |
| CO alarm | Required in any unit where a fossil-fuel burning appliance, attached garage, or generator is present. |
| Fire extinguisher | Minimum 2.5 lb ABC-rated (or 5-B:C equivalent), mounted within 2 feet of the main entry door. |
| Egress opening | Minimum 5.7 sq ft clear opening, 24″ min height, 20″ min width, 44″ max sill height above finished floor. |
| Plans approval gate | Construction drawings, electrical plans, plumbing plans, and VIN documentation must be approved before Stage 1 begins. |
| GPS-tagged photography | Photos are captured within the CERTAFI inspection platform and recorded as part of the permanent inspection record. |
| Live video at all stages | Stages 1–5 require live video walkthroughs captured within the CERTAFI platform. |
| Serial number plate | A CERTAFI serial number plate must be affixed and readable before final approval. |
| Digital certificate and verification page | Stage 5 approval issues a PDF certificate and activates a permanent public verification page linked by QR code. |
| 140 mph wind load target | Used as an internal structural guidance benchmark for anchoring and connection design. |
Optional systems
When an optional system is included in a build, additional CERTAFI+ inspection requirements apply at the relevant stages. These requirements are CERTAFI+ proprietary requirements — performance-based and documentation-based. They do not constitute enforcement of any external code, manufacturer specification, or regulatory standard. Builders remain responsible for all applicable permits and jurisdiction-specific requirements related to any optional system.
- All gas components securely mounted and protected from physical damage and road vibration
- Shutoff valves accessible, clearly identifiable, and functional
- All connections tested for leaks using an approved detection method — leak test results documented and submitted
- Gas lines properly routed, supported, and protected where they pass through structural members
- Propane tanks secured for road transport and protected from heat sources
- Indoor and outdoor units securely mounted for road transport
- Refrigerant line sets properly routed, protected, and supported
- Condensate drainage routed to an appropriate exterior discharge point
- Electrical connections properly sized, protected, and installed per manufacturer specs
- System tested for proper operation and demonstrated functional at final inspection
- Solar panels securely mounted and rated for structural loads and wind conditions associated with road transport
- Wiring and conduit properly routed, protected, and secured
- Battery systems mounted in a ventilated, accessible location appropriate for the battery chemistry
- Overcurrent protection present at all required points in the system
- System demonstrated functional and properly integrated with the unit's electrical system at final inspection
- Unit properly sized for the electrical service available
- Dedicated circuit protection installed per manufacturer specs
- Unit securely mounted and protected from physical damage
- Supply connections leak-free and demonstrated under pressure test
- Unit tested for proper operation at final inspection
- Unit securely mounted and supported for road transport
- Ventilation provided to the exterior per manufacturer specs
- Electrical connections properly installed and protected (where present)
- Access panels and maintenance points remain accessible
- Installation must not compromise floor, wall, or subfloor structural integrity at the mounting location
- Washer drain connections require a minimum 2-inch drain standpipe
- Hot and cold water supply connections leak-free and tested under pressure
- Dryer venting routed to the exterior and properly secured (where present)
- Gas dryer connections subject to the LP gas system requirements
- All appliances secured for road transport
- Guardrail required at any open loft side more than 24 inches above adjacent floor — minimum 34 inches height, openings no greater than 4 inches
- Lofts 35 sq ft or greater require both a primary and secondary means of egress
- Minimum loft floor area: 35 sq ft with minimum 5-foot horizontal dimension
- Separate smoke alarm required inside each closed loft or sleeping area
- All Stage 5 life safety requirements apply to the loft space
Certification
When Stage 5 (Final Inspection) is approved, the CERTAFI system automatically generates a digital certificate PDF, assigns a unique permanent serial number, and activates the public verification page at getcertafi.com/verify/[serial].
The certificate reflects the condition of the unit as documented and reviewed through the CERTAFI+ inspection process at the time of each stage submission. It is issued under the CERTAFI+ Enhanced Building Standard (v1.0) only.
CERTAFI+ certification does not constitute compliance with NFPA 1192, ANSI A119.5, NEC, IRC, or any external code or standard. Those publications are used solely as background reference material. Builders and owners remain solely responsible for all applicable local, state, and federal requirements.
Referenced standards & resources
The following publications are used as background reference material only to inform portions of the CERTAFI+ standard. CERTAFI+ certification does not confirm compliance with any of these publications.
Standard on Recreational Vehicles
https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=1192
Park Model RV Standard
https://shop.iccsafe.org/
National Electrical Code — RV and park trailer articles
https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/nfpa-70
International Residential Code (reference where RV standards are silent)
https://codes.iccsafe.org/content/IRC2024P2
American Wood Council — wood framing guidance
https://awc.org/
APA — The Engineered Wood Association
https://www.apawood.org/
Questions
Inspection and submission questions: inspectors@getcertafi.com
General inquiries: support@getcertafi.com