MOISTURE MANAGEMENT
Code Minimums for Exterior Foam
Zone 6 2x4 walls: R-7.5
1.25” polyiso @ R-6/in 1.875” mineral wool @ R-4/in
2x6 walls: R-11.25 1.875” polyiso @ R-6/in 2.812” mineral wool @ R-4/in
GWP
Source: Avoiding the Global Warming Impact of Insulation Posted June 01, 2010 03:20 PM by Alex Wilson, buildinggreen.com
Interior Management Strategies
DehumidifiersBath fansRange hoodsSump pitsHRVs/ERVsTarget: < 45%
Exterior Management Strategies
OverhangsGuttersRainscreensThick foam and NO POLYPlywood
When walls go bad.
Follow These Guidelines:
Air leaks are bad. Air-permeable insulation is risky. The thicker the wall, the colder the
sheathing, and the riskier your wall. Rainscreens are good GREAT. Avoid OSB if possible where it’ll get wet. Exterior foam? Make it thick. Reverse laps are bad.
Source: How Risky Is Cold OSB Wall Sheathing?Posted on Nov 5 2010 by Martin Holladay, GBA Advisor
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