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Specify insulation levels and avoid thermal bridges

Insulation resists heat flow and is measured as R-value (higher is better). The level you need depends on climate zone and part of the building.

How

1. Look up recommended or minimum insulation for roof, walls and floor in your local code. In the US, DOE publishes suggested R-values by climate zone based on the 2021 IECC.
2. Aim above the minimum where budget allows; Your Home notes roofs lose 25 to 35 percent of winter heat, walls 15 to 25 percent and floors 10 to 20 percent.
3. Wrap insulation continuously around the heated volume, including slab edges and band joists.
4. Break thermal bridges: steel framing and container walls need insulated thermal breaks to reduce condensation (NZ, Your Home).
5. Use the heat loss calculator below to compare wall and window options.
6. Never compress batts; fill cavities fully.

Sources

1. Insulation. US Department of Energy, Energy Saver, accessed 2026-11
2. Passive heating. Your Home, Australian Government, accessed 2026-11
3. Construction systems (Smarter Homes guides). Building Performance, New Zealand Government (MBIE), accessed 2026-11
4. Construction systems. Your Home, Australian Government, accessed 2026-11

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