Container → Livable Space
- • Steel = R-0 — insulation is everything
- • Condensation on steel is the primary challenge
- • Ventilation is mandatory (containers are airtight when sealed)
- • MA Zone 5A: R-20 walls, R-49 roof minimum
IRC 2021780 CMRASHRAE 62.2IECC R402
Container Type
External
20' x 8' x 8.5'
Internal
19.33' x 7.67' x 7.83'
Floor Area
148 sqft
Tare Weight
4,850 lbs
Insulation Strategy
Wall Cross-SectionOutside → Inside
Not enough insulation at 3"
R-19.7 effective — need at least R-20. Try 4" thickness.
R-19.7
Effective (after 5% thermal bridge loss)
Nominal: R-20.7
Wall R-Value
Code Compliance
Base Code (R-20)FAIL
Need R-0.3 more — increase to 4" thickness
Stretch Code (R-25)FAIL
135 sqft
7.2ft wide x 19.33ft long
Ceiling: 7.6ft
Lost to insulation: 13 sqft
Usable Interior
Min. Ventilation (ASHRAE 62.2)
20 CFM
Based on 2 occupants, 135 sqft
Ventilation (ASHRAE 62.2)
Conversion Checklist
Key Code References
| Requirement | Code | Value (Zone 5A) |
|---|---|---|
| Wall Insulation | IECC R402.1.2 | R-20 or R-13+5ci |
| Roof Insulation | IECC R402.1.2 | R-49 |
| Floor Insulation | IECC R402.1.2 | R-30 |
| Window U-Factor | IECC Table R402.1.2 | U-0.30 max |
| Air Leakage | IECC R402.4.1.2 | 3 ACH50 max |
| Ventilation Rate | ASHRAE 62.2-2022 | 0.03 × CFA + 7.5 × (Nbr + 1) CFM |
| Egress Window | IRC R310.1 | 5.7 sqft min, 24" min height |
| Smoke Detectors | IRC R314.3 | Each bedroom + outside sleeping area |
| CO Detectors | IRC R315.3 | Outside each sleeping area |
| Vapor Retarder | IRC R702.7 | Class I or II on warm side |
| Thermal Barrier | IRC R316.4 | 1/2" drywall over spray foam |
| Electrical in Steel | NEC 334.10 | EMT conduit (not Romex on steel) |
Educational reference only. Consult a licensed engineer and your local building department.
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