Insulation & air sealing
Insulation slows heat flow; air sealing limits uncontrolled air movement. Good building performance usually depends on both, along with moisture control and correct installation.
Quick reference
| Item | Planning data |
|---|---|
| R-value | A measure of thermal resistance. Higher R-value means greater resistance to heat flow for the tested material/thickness. |
| Fiberglass batts | Common in framed cavities; fit and continuity matter, and compression can reduce effective performance. |
| Loose-fill insulation | Often used in attics or enclosed cavities with product-specific installed-depth and coverage charts. |
| Rigid foam | Can provide continuous insulation, but fire protection, vapor behavior, attachment, and compatibility depend on where it is used. |
Values marked common or typical are starting points, not a specification. Confirm the actual product data sheet, label, and project documents.
Start with the assembly
The right insulation depends on climate, framing depth, existing materials, air leakage, vapor control, and whether the location is an attic, wall, crawlspace, basement, or roof.
Read the coverage chart
For loose-fill products, bags per area vary by target R-value, settled depth, and product. Use the exact manufacturer's chart rather than a generic bag estimate.
Air sealing and ventilation
Seal appropriate gaps before adding insulation, while preserving required ventilation and combustion air. Do not block soffit ventilation or cover heat-producing equipment and required clearances.
Common mistakes
Blocking attic airflow; covering unsafe recessed lights or flues; trapping moisture in the wrong part of an assembly; and installing insulation around unresolved leaks or dampness.
Continue planning
Further reading: Manufacturer or industry reference ↗. External guidance may not replace local requirements or product-specific instructions.