air barrier

One Air Barrier or Two?

Posted on January 29,2015 by user-756436 in air barrier

Although building scientists have understood the advantages of airtight construction details for years, few residential plans include air barrier details. That’s nuts.

Do the blueprints show where the air barrier goes?

Ideally, construction documents should show the location of a building’s air barrier, and should explain how the builder is expected to maintain air-barrier continuity at penetrations and important intersections.

Airtight Wall and Roof Sheathing

Posted on January 29,2015 by user-756436 in air barrier

UPDATED on December 12, 2014 In the early 1970s, residential builders knew almost nothing about air tightness. The first residential air barriers were installed in Saskatchewan in the late 1970s, when pioneering Canadian builders began sealing the seams of interior polyethylene sheeting with Tremco acoustical sealant. The Canadian builders (and their American imitators) went to a lot of trouble to weave the interior poly around framing members at rim-joist areas and partition intersections.

Forget Vapor Diffusion — Stop the Air Leaks!

Posted on January 29,2015 by user-756436 in air barrier

Last week’s blog answered some common questions about vapor retarders. This elicited a comment from Bill Rose, research director of the Building Research Laboratory at the University of Illinois in Champaign. “We might imagine a future in which the building code sections that address the vapor barrier would all go blank,” Rose wrote.

Air Barrier or Vapor Barrier? - Building Science Podcast

Posted on January 29,2015 by JoeLstiburek in air barrier

_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._

Architects Talking About Air Barriers

Posted on January 29,2015 by ChrisBriley in air barrier

With cocktails in their hands, architects Chris Briley and Phil Kaplan discuss green building and design issues in a casual, pithy format Join the guys for a drink as Chris and Phil look at air barriers — one of “The Big Three” topics (along with insulation and windows) of green construction. Sit back, relax, and be “edutained” — while you work, drive, exercise or do whatever you do while you podcatch.

Can Spray Foam Rot Your Roof?

Posted on January 29,2015 by Daniel Morrison in air barrier

Ice dams are a familiar problem in New England and other parts of the country where winters are long and cold. Snow on under-insulated and under-ventilated roofs melts, pools and refreezes to form a dam. Water backs up under the shingles and much to the horror of homeowners often finds its way inside the building. Spray foam polyurethane insulation is supposed to be a hedge against that problem. By forming an effective seal around rafters, and offering respectable R-values, foam should be blocking the migration of cold air into the roof where it can condense into water.

How Air Affects a House (2) - Building Science Podcast

Posted on January 29,2015 by John Straube in air barrier

_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._

Installing Fiberglass Right

Posted on January 29,2015 by user-756436 in air barrier

Of all of the commonly used types of insulation — including cellulose, rigid foam, and spray polyurethane foam — fiberglass batts perform the worst. As typically installed, fiberglass batts do little to reduce airflow through a wall or ceiling assembly; rarely fill the entire cavity in which they are installed; and sometimes permit the development of convective loops that degrade insulation performance. Knowing this, why would any builder choose to install fiberglass batts? The answer is simple: because fiberglass batts cost less than any other type of insulation.

Green Basics The Building Envelope
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