10 Major Energy Retrofits

The best time to make major energy retrofits (also called deep energy retrofits) is during a renovation. This is when you’re making major changes to the building, and probably getting a building permit. Ideally, the house will be vacant during this process. Here are...

Choosing Roof Designs for New Buildings

A roof’s purpose Before you choose a roof design for a new building, you should understand the purpose of a roof. The primary purpose of roof is to shed rainwater and snow. A secondary purpose — and a less appreciated one — is to provide shade. A roof’s enemies...

Rainscreens and drainage planes

Building assemblies can get wet Building scientists assume that some rainwater leaks through the cladding or roofing and that water vapor migrates through insulated building assemblies, sometimes condensing within those cavities. These two phenomena both can dampen...

Possibilities for Wetting of Cellulose Insulation Part 2

Relative Humidity, Temperature, and Moisture Content This is Part 2 of a two-part series on cellulose insulation and moisture. Cellulose insulation is a hydrophilic material, meaning that absorbs moisture readily. Under certain conditions condensation dampens...

Air and Water Barriers

Old and new water barriers Once upon a time, builders stapled 15-pound asphalt felt to wall and roof structural sheathing as a water-resistive barrier (WRB). The 2012 International Residential Code (IRC) still specifies: “one layer of No. 15 felt… or other approved...

Hygric Buffering & Cellulose Wall Insulation

This is a two-part blog about hygric buffering, cellulose wall insulation, and moisture problems in high-performance buildings. Why not to install cellulose insulation in deep wall cavities Cellulose shrinks, slumps, and dries very slowly after wetting. Deep wall...