Insulating a Balcony Conversion
When a balcony is converted to habitable living space, its floor, walls, and ceiling become part of the home's thermal envelope. The International Energy Conservation Code (IECC) sets minimum R-value requirements by climate zone. In mixed climates (Zone 4–5), floors typically need R-13 to R-20; walls, R-13 to R-20; ceilings, R-38 or more.
This calculator estimates insulation thickness and volume based on your climate zone and insulation type. Total material includes the floor area plus an estimated 2.5× for walls and ceiling, with a 10% waste factor. Always verify with your local building department's specific code requirements.
EPS rigid foam is economical and easy to cut. XPS offers higher moisture resistance, making it ideal for floors and below-grade applications. Polyiso gives the highest R-value per inch but is best used above the dew point (not recommended for below-grade use due to moisture performance at cold temperatures).
Frequently Asked Questions
Yes. Fiberglass or mineral wool batts work in framed cavities. Combine with rigid foam on the exterior or interior face for higher R-values without increasing framing depth.
In cold climates, a vapor retarder on the warm-in-winter side of insulation prevents condensation within the assembly. Consult local code — vapor control requirements vary significantly by climate zone.