sheathing

Is Oriented Strand Board as Impermeable as They Say?

Posted on April 02,2015 by ab3 in oriented strand board

Oriented strand board (OSB) gets blamed for a lot of problems that are really the fault of the designers and builders. Part of the problem, of course, is the perrenial confusion between correlation and causality. OSB hit the market as we really started getting serious about insulation and air sealing.

How to Seal Sheathing Boards

Posted on April 02,2015 by ScottG in air-sealing

The use of plywood and OSB sheathing is a fairly recent phenomenon. Before these sheet goods became readily available, builders nailed wood boards to the frame of a house for sheathing, and it is a house with this type of sheathing that Nick Welch is trying to update. His 900-square-foot house in Climate Zone 4C is sheathed with 1x8 boards, apparently over a layer of asphalt felt. There is apparently no insulation in the wall cavities behind the sheathing. His plan of attack is to air-seal the house, then install foil-faced polyisocyanurate insulation over that. The question is how.

Solving Comfort Problems Caused by Attic Kneewalls

Posted on April 02,2015 by ab3 in air barrier

In Texas, they call them “hot walls.” My friend Mike Barcik likes to say they’re what separate you from the blast furnace. Down here in the warmer climate zones, where attics get up to 8,000°F (well, that may be a slight exaggeration), many people call them a liability. (Sadly, architects haven't gotten the message.)

Does Your Air Barrier Work in Both Directions?

Posted on April 02,2015 by ab3 in air leakage

Do you want a good air barrier on your house? Of course you do. No one who knows anything at all about building science believes that old myth that a house needs to breathe. We want airtight houses, but then we want mechanical ventilation to bring in fresh air from outside (well, at least as fresh as you can get from your outside).

How Risky Is Cold OSB Wall Sheathing?

Posted on April 02,2015 by user-756436 in cold OSB

During the winter months, wall sheathing is usually cold. Cold sheathing is risky, since it tends to accumulate moisture during the winter. Unless the sheathing can dry out during the summer months, damp sheathing can rot.

Airtight Wall and Roof Sheathing

Posted on April 02,2015 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.

How Much Insulation is Needed?

Posted on April 02,2015 by AlexWilson in expanded polystyrene

Standard residential construction in much of the country is 2x4 framing with fiberglass insulation, achieving a paltry R-10 or so in the walls. If insulation is installed at all on the foundation walls, it’s rarely more than an inch thick, and insulation is almost never put under slabs. In Vermont, we typically do a lot better. Act 250, enacted nearly four decades ago, required developers to improve energy performance and that led to a widespread switch to 2x6 framing in home building.

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