air leak

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Is OSB Airtight?

Posted on March 04,2015 by user-756436 in air barrier

UPDATED on December 16, 2014 Most builders assume — and GBA has long reported — that oriented strand board (OSB) is a good air barrier. If a builder uses a high quality tape like Siga Wigluv, Zip System tape, or 3M All Weather flashing tape to seal sheathing seams, OSB wall and roof sheathing can act as a building’s primary air barrier.

Air Leaks From Your Home To Your Attic Need To Be Sealed

Posted on March 04,2015 by Tamasin Sterner in air leak

It’s important to keep attic air out of the house and house air out of the attic. That's why the home performance industry and every above-code building program make it a top priority to fully separate attics from the rest of the building. When the attic isn’t fully air sealed from the living space and the combustion appliance zone, three undesirable scenarios can occur:

Fixing a Leaky Log Home

Posted on March 04,2015 by ScottG in air leak

Early settlers who felled their own trees to build log homes were probably so grateful to be out of the weather they didn't worry about air leaks or cold walls. But when your heating bills are $500 a month, it's a different story altogether. That's the situation facing ADK Homeowner, as he explains in a Q&A post at Green Building Advisor.

The Street-Side Energy Audit

Posted on March 04,2015 by user-1048334 in air leak

When my wife and I bought our current house, one of the home’s appeals was that it was largely uninsulated. Given the choice between somewhat insulated and uninsulated, give me the blank slate every time. We moved in in September, and because of a super-busy energy audit season and the need to unpack, any desired home-improvement projects were temporarily back-burnered.

Air Leaks in Homes Insulated With Spray Foam

Posted on March 04,2015 by user-1072052 in air barrier

If you’re retrofitting a vintage brick building without an air barrier, don’t count on the spray foam to create a perfect air seal. If you plan to use the spray foam as your air barrier, it's important to test your work before you cover it with drywall so you can seal any air leaks.

Rescuing a Problem Cathedral Ceiling

Posted on March 04,2015 by ScottG in air leak

You could call it the $6,500 problem, because that's what it's going to cost Kacey Zach to re-insulate a cathedral ceiling with closed-cell polyurethane foam and hang new drywall. Writing at Green Building Advisor's Q&A forum, Zach explains the situation: a cathedral ceiling framed with 2x12s and insulated with fiberglass batts to R-38 "with no regard to air sealing."

Air Sealing an Attic

Posted on March 04,2015 by user-756436 in air leak

If you want to improve the energy performance of an older house, one of the first steps is to plug your attic air leaks. Although many GBA articles address aspects of attic air sealing, no single article provides an overview of the topic. This article is an attempt to provide that missing overview. I’ll try to explain how you can seal air leaks in a conventional vented, unconditioned attic. If your house has cathedral ceilings — that is, insulated sloped roof assemblies — the air sealing tips in this article don’t apply to your house.

Energy Upgrades for Beginners

Posted on March 04,2015 by user-756436 in air leak

Owners of older homes often contact GBA and ask, “What can I do to make my home more energy-efficient?” My standard answer goes something like this: “The first step is to hire a certified rater to perform an energy audit of your home. The audit report will include a tailor-made list of retrofit measures to address your home’s specific problems.”

Meet the Tightest House in the World

Posted on March 04,2015 by ScottG in ach50

A Dillingham, Alaska, couple has claimed a world record for airtightness in a 600-sq. ft. home with 28-in. thick walls and a ceiling rated at R-140. According to the World Record Academy, a blower-door test measured 0.05 air changes per hour at 50 pascals of pressure (ACH50), less than 10% of the very rigorous Passivhaus air-tightness standard of 0.60 ACH50.

EcoSeal: A New System for Air Sealing Homes

Posted on March 04,2015 by AlexWilson in air leak

Getting back to our Dummerston, Vermont farmhouse this week, I’m reporting on our use of a relatively new product for air-sealing homes: EcoSeal from Knauf Insulation. First some context: In the building science world, there is growing interest in achieving a robust air barrier at the sheathing layer of a house, with layers inside of that able to dry toward the interior and layers on the outside able to dry to the exterior. To make that work, the sheathing layer has to be tightly air-sealed.

Air Leakage at Electrical Switches and Outlets

Posted on March 04,2015 by ab3 in ADA

One thing that invariably surprises people when I walk them through a house during their first blower-door test is how much air leaks in through the electrical switches and receptacles. On a recent Friday, we went out to do the last home energy rating in our latest HERS rater class, and we got to see something even better. But first, let's talk about that air leakage. We have a number of surprises waiting.

How to Insulate and Air-Seal Pull-Down Attic Stairs

Posted on March 04,2015 by user-1048334 in air leak

Pull-down attic stairs are super-sized attic hatches that just beg homeowners to store more stuff in their attic. Besides the air-leakage and insulation problems stemming from having a particularly large hole in your ceiling, pull-down stairs creates a potential storage headache. For homeowners, a storage problem usually means “not enough space.” For energy auditors, a storage problem means using space that ought to filled with insulation for Timmy’s guitar, his old bike, Legos, his new bike, and the unpacked remains of twelve previous moves.

How to Insulate and Air Seal an Attic Hatch

Posted on March 04,2015 by user-1048334 in air leak

There’s a subset of issues in the realm of home efficiency that falls into the category “out of sight/out of mind.” The boiler in the basement, how much insulation is in the attic … as long as these issues stay out of your view, no problem. So what’s up with attic hatches, then? Even though attic hatches can be huge air leaks and sources of radiant heat loss, they are rarely fixed. An attic hatch is usually located in a hallway or closet where the homeowners see it daily. Yet...

Top 10 Air Leaks in Existing Homes – Part 2

Posted on March 04,2015 by Tristan Roberts in air barrier

From an energy-efficiency standpoint, the trouble with owning an old home is that you’re stuck with whatever bad decisions the previous owners made, and historical trends also tend to work against you. The trouble with building a new home is that you are the one that is going to make the bad decisions. The best opportunity to make important decisions that will deliver energy efficiency for the life of the home is during design. There is rapid diminution of these opportunities during construction and then during use of the home.

Top 10 Air Leaks in Existing Homes — Part 1

Posted on March 04,2015 by Tristan Roberts in air leak

Whenever we’re working on the outside of a home—the roofing, siding, or site—my uncle Chris will remind me to think like a drop of water. Mentally tracing how a raindrop is likely to travel down a building, and including details to move it off and away, is a simple exercise that is too often ignored. Today, though, we’re going to talk not about water but about air. I have a new exercise to propose to Chris: think like a wisp of air.

Questions and Answers About Air Barriers

Posted on March 04,2015 by user-756436 in air barrier

UPDATED on December 12, 2014 Builders of a certain age — say, those older than about 55 or 60 — started their careers at a time when no one talked about air leakage or air barriers. Back in the early 1970s, even engineers were ignorant about air leakage in buildings, because the basic research hadn’t been done yet. Times have changed, and most residential building codes now require builders to include details designed to reduce air leakage. Today’s young carpenters are working on job sites where air barriers matter.

One Air Barrier or Two?

Posted on March 04,2015 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 March 04,2015 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.

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