Building Science

This podcast series is excerpted from a two-day class called "Building Science Fundamentals" taught by Dr. Joe Lstiburek and Dr. John Straube, of Building Science Corporation.

This podcast series is excerpted from a two-day class called "Building Science Fundamentals" taught by Dr. Joe Lstiburek and Dr. John Straube, of Building Science Corporation.

This podcast series is excerpted from a two-day class called "Building Science Fundamentals" taught by Dr. Joe Lstiburek and Dr. John Straube, of Building Science Corporation.

This podcast series is excerpted from a two-day class called "Building Science Fundamentals" taught by Dr. Joe Lstiburek and Dr. John Straube, of Building Science Corporation.

This podcast series is excerpted from a two-day class called "Building Science Fundamentals" taught by Dr. Joe Lstiburek and Dr. John Straube, both of Building Science Corporation.

For over 2,000 locations across the country, there are hourly weather data files packed with temperature, humidity, and wind information that can be used to better match home designs to the conditions they will face. But to say that all this information is dense and overwhelming is a bit of an understatement.

This podcast series is excerpted from a two-day class called Building Science Fundamentals with Drs. Joe Lstiburek and John Straube of Building Science Corporation. For information on attending a live class, go to BuildingScienceseminars.com This week Dr. Joe talks about enclosure design principles of energy efficient buildings

Housewraps and Building PaperTypically referring to Grade D building paper, this product is an asphalt-impregnated kraft paper that looks a lot like a lightweight asphalt felt. The Grade D designation has come to mean that the building paper passes ASTM D779 (minimum 10-minute rating with the “boat test”) and different products are called out as “30-minute” or even “60-minute” based on D779 results. At times confused with roofing felt, roofing felts and building paper differ in two ways: felts are made of recycled-content paper, building papers of virgin paper; felts are made of a heavier stock paper; building papers a lighter stock. See also roofing felt.: Beyond Water Resistance

Tensile strength, vapor permeability, and pliability are important, too.

In a recent blog post, I covered water-resistive barrierSometimes also called the weather-resistive barrier, this layer of any wall assembly is the material interior to the wall cladding that forms a secondary drainage plane for liquid water that makes it past the cladding. This layer can be building paper, housewrap, or even a fluid-applied material. (WRB) tests to separate the wheat from the chaff in terms of water resistance. But a good WRB has other properties as well.

How do you know if your housewrap really works?

In the good old days, we weatherlapped 3-ft. courses of building paperTypically referring to Grade D building paper, this product is an asphalt-impregnated kraft paper that looks a lot like a lightweight asphalt felt. The Grade D designation has come to mean that the building paper passes ASTM D779 (minimum 10-minute rating with the “boat test”) and different products are called out as “30-minute” or even “60-minute” based on D779 results. At times confused with roofing felt, roofing felts and building paper differ in two ways: felts are made of recycled-content paper, building papers of virgin paper; felts are made of a heavier stock paper; building papers a lighter stock. See also roofing felt. underneath our wall claddings, and that seemed to work just fine. But then along came all sorts of snazzy “gift wrappings” (a.k.a. housewraps) in handy, 9-ft. rolls. Some claimed to be both air barriers as well as water-resistive barriers; others claimed to be vapor permeable. Along the way, it got pretty confusing about just exactly what the housewrap’s job is in our walls. (For a practical and detailed perspective on housewraps, see “Making Sense of Housewrap”.)

The homeowners called me after a certified home inspector stated that the attic was underventilated and moisture was building up as a result. The roof assembly had soffit vents at the eaves and two gable-end vents. These vents would not be as effective as ridge-to-soffit ventilation, but were probably close to building code requirements (see Green Basics – Attics).