Isolamento R-Value por Zona

R-value by climate zone

R-value is a measure of thermal resistance, worked out as R = thickness ÷ thermal conductivity. A higher R means better insulation. Typical fiberglass batts come in at R-13 at 3.5" for 2x4 walls and R-19 at 6.25" for 2x6 walls. Down in IECC zone 1 (south Florida) the walls only need R-13, while cold zones like Canada or the northern US call for R-15 in walls and anywhere from R-30 to R-49 in attics. Put an R-19 batt plus R-5 continuous foam in a 2x6 wall and the assembly works out to R-24. In Brazil most homes skip insulation entirely, since the climate is mild.

Applications

You'll see R-value come up in residential and commercial construction, in retrofit jobs, energy audits and LEED certification. A higher R cuts the HVAC load and the running cost. The usual materials are fiberglass batt, mineral wool, cellulose, EPS, XPS, polyiso (PIR) and spray foam. One thing to watch is thermal bridging through the studs. Continuous exterior insulation takes care of most of it.

FAQ

Does R-value apply in Brazil? The idea carries over, but Brazilian standards work in U-value and the NBR 15220 thermal zones. You mostly run into R on imported materials.

Can I stack insulation? Yes. R-values add up in series, so an R-13 batt plus an R-5 foam board gives you R-18 effective.

Does more R always pay off? No. Past a certain point the energy you save no longer covers what the extra material costs. Stick to the IECC table for your zone.