air sealing

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Spray Foam Insulated Homes Need Ventilation

Posted on April 21,2015 by ab3 in air sealing

Most installations of spray foam insulation, when properly installed, act as an air barrier. When you use it instead of the fluffy stuff (fiberglass, cellulose, cotton), a house will be more airtight. That's good.

When a house is airtight, the nasties in the indoor air tend to stick around. Volatile organic compounds (VOCs), water vapor, odors, radon, and other stuff you don't want to immerse yourself in make the home's indoor air quality worse.

Seeking the Elusive Grade 1 Batt Installation

Posted on April 21,2015 by CarlSeville in air sealing

Having spent much of my time writing for GBA whining and complaining about the state of the insulation industry, it is now time for me to eat a little crow. The insulation work at one of our multifamily certification projects has, amazingly, met – and even possibly exceeded – my expectations for quality.

What’s More Important, Air-Sealing or Insulation?

Posted on April 21,2015 by ScottG in air sealing

Green Building Advisor reader Ani Brown is getting ready to build a new house, and like most people in her position Brown will have to make some important choices on how to make the most of a limited construction budget. Her immediate concern is insulation and air-sealing, two related details that will have a lot to do with how comfortable and durable the new house will be.

Multifamily Green Building Certification Still Has Issues

Posted on April 21,2015 by CarlSeville in air sealing

Much of my work these days involves certification of multifamily buildings, and, thanks to a boom in apartment construction, my partner and myself are staying occupied. The one major contrast from single-family residential work, with which I am most familiar from my days as a contractor, is the long lead time. I still find it amusing that I sign a contract, have an initial start-up meeting with the developer and contractor, and often don’t see the project for another year or more, when the builder is ready for our insulation and air-sealing inspections.

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

Posted on April 21,2015 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:

A Review of Siga Wigluv Air-Sealing Tape

Posted on April 21,2015 by Matt Risinger in air barrier

Every house needs four control layers. In order of importance, these layers need to provide:

  1. 1. Water control
  2. 2. Air control
  3. 3. Vapor control
  4. 4. Thermal control
The building codes have dictated the levels of thermal control and vapor control that builders must adhere to, and nearly every builder in the U.S. knows off the top of their head the R-value of the insulation in their walls and attics.

Using Interior Poly As an Air Barrier

Posted on April 21,2015 by user-756436 in air barrier

Back in the 1980s, Canadian energy experts urged builders to use interior polyethylene as an air barrier material. If the poly was installed conscientiously, and all seams were sealed with Tremco acoustical sealant, the approach worked well — at least in cold climates.

Ban the Can

Posted on April 21,2015 by user-1048334 in air leakage

One hates to overstate how problematic recessed lights can be, but… they sure are a pain in the energy-auditor butt. There are worse problems (wet basements), more expensive ones (insulating a complicated roof line), and more frustrating ones (the cross-purposes of energy evaluations and homeowner desires). But few elements of the house combine all three in as tidy a package as recessed light cans.

Plugging Air Leaks Would Save Billions

Posted on April 21,2015 by ScottG in air leakage

Bringing all U.S. homes to airtightness levels spelled out in the 2012 International Energy Conservation Code would save as much as $33 billion in energy costs annually, according to new research at the Lawrence Berkeley National Laboratory.

Providing Outdoor Combustion Air for a Wood Stove

Posted on April 21,2015 by westychris in air sealing

In November 2012, I started on a deep energy retrofit of my 1976 raised ranch in northwestern Vermont, in the shadow of Mount Mansfield. As a Passive House consultant, I wanted to make my leaky (8.25 ach50) house with fiberglass-filled 2x4 walls and a tuck-under garage much more energy-efficient.

Air Sealing an Attic

Posted on April 21,2015 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.

Why Weatherization Isn’t Enough

Posted on April 21,2015 by user-982535 in air sealing

Ask almost any building performance expert what you should do first to cut your utility bills and improve the energy efficiency of your home, and the answer will inevitably be to weatherize. And that’s as it should be. Most of our homes are rife with air leaks. According to the U.S. Department of Energy, in the average American home, 30 cents of every dollar spent on heating and cooling is lost to air leaks and insufficient insulation.

Getting the Biggest Bang for Your Air-Sealing Buck

Posted on April 21,2015 by user-756436 in air leakage

Most new homes are leaky. In the typical new home, significant volumes of air enter through cracks near the basement rim joists and exit through ceiling holes on the building’s top floor. These air leaks waste tremendous amount of energy.

What Makes the ‘Best’ Air Barrier?

Posted on April 21,2015 by ScottG in air sealing

Bill L. is planning a high-performance house in Massachusetts and is wrestling with options for the air barrier, that all-important building detail that enhances both energy efficiency and building durability. Above-grade walls will consist of a 2x4 structural frame sheathed in 1/2-inch plywood, followed by I-joists packed with cellulose insulation, another layer of 1/2-inch plywood, a corrugated plastic product to provide an air space, and fiber-cement siding. The primary air-barrier plane will be at the plywood over the 2x4 studs.

Tighter Houses with Less Effort

Posted on April 21,2015 by ScottG in Aeroseal

Builders who specialize in high-performance houses spend a lot of time tracking down and correcting air leaks. The process can involve a number of materials and sealants, such as special gaskets, tape, and caulk, plus a lot of time and attention to install them correctly. Researchers at the Western Cooling Efficiency Center at the University of California-Davis think they've found a way to make the process much faster and easier.

EcoSeal: A New System for Air Sealing Homes

Posted on April 21,2015 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.

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