Insulation before equipment
Sizing a mini-split before insulating is backwards. Every R-value you add lowers required BTU and improves comfort between cycles.
Tiny envelopes heat and cool fast — poor insulation means oversized equipment, condensation on cold surfaces, and mold risk in wall cavities.
Plan insulation during build or retrofit, then run BTU numbers. This guide is DIY planning information, not a building science consultation.
Common tiny home insulation choices
- Closed-cell spray foam: highest R per inch, air seals in one step — popular in THOWs
- Rigid board (XPS or polyiso): good for roof and floor packs before interior finish
- Mineral wool in stud bays: breathable, good for sound — pair with air barrier tape at seams
- Windows: low-E double-pane minimum; triple-pane worth it in cold climates
- Thermal bridge breaks at metal studs and trailer frame contact points
Air sealing matters as much as R-value
A tiny home with R-20 walls but leaky window trim behaves like poor insulation in the calculator. Seal penetrations for plumbing, electrical, and hitch flex points before closing walls.
After sealing, re-run your BTU estimate with "good" or "average" insulation instead of "poor" — you may drop one full head size.