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The Building Envelope and Insulation

Home IQ focuses on the latest technologies in insulation and air quality that were utilized in the Oberg home and how the "building envelope" (area of construction between the inside and outside of the home) was created.

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building envelope and insulation

The concept of having multiple layers in your building envelope to make the house perform better is similar to a new jacket with an inner fleece lining to keep you warm. The lining keeps you warm and the outer shell of the jacket keeps moisture and wind (air) out. The same works for a building envelope.

All the cracks, gaps and seams in a building's envelope break down the insulation and air quality of a home, and the better you can make your home air-tight.

Did You Know? — Enough air escapes the typical American home every day to fill the Goodyear Blimp.

Quality Insulation System

There are three components to a good insulation system:

  • Thermal Issue — This involves the comfort, heat loss or gain and how these affect the heating system.

  • Air-Leakage Control — How much air is lost in a house due to drafts, etc.

  • Moisture Management — This is the newest component.

    The main goal of insulation is to resist the cold temperatures of winter and the hot temperatures of summer. The more your home's insulation can resist thermal transfer, the higher its resisting value.

    This measure of resistance is what the "R" stands for in R-values when evaluating commercial insulation. For example, a typical old house may have had a wall of insulation with an R-value of 12 or 14 or in that range — yet, in the Oberg house this value is a 21.

    Outside Insulation for the Oberg Home

    One of the ways the Oberg house was able to achieve this high R-value was by insulating the outside of the house, as well as the inside.

    Here are some of the forms of insulation utilized on the outside:

    • Rigid Foam Board insulation — This is an exterior sheeting that insulates and reduces any thermal bridging to the inside of the home. This particular board serves as a moisture barrier and is part of the drainage plane of the house.

      Note: The drainage plane is the secondary plan for reducing moisture into the house because exterior building products aren't 100 percent waterproof.

    • House Wrap insulation — This form of insulation (DuPont Tyvek® in this particular case) is part of the drainage plane and a secondary installment to reinforce keeping moisture out of the house. In other words this is an "additional" layer of protection of insulation for the home. House wrap is easily installed as well.

    • Tuff-N-Dri® Basement Waterproofing System — This is a two-part system that protects the basement:

    -The first part is a polymer-enhanced asphalt that is sprayed onto the block exterior walls of the basement. This bridges any cracks or gaps in the foundation that occur naturally over time.

    -The second part is a Warm-N-Dri® Foundation Board that is installed over the asphalt spray. It provides backfill protection, insulation and drainage. As water hits the boards it will drain right down through the board and into the drainage system around the perimeter of the foundation.

    Protecting and insulating the basement walls is "always" a good idea, but it's especially important if you plan to use this area as a living space, which is what Lynn and Brad Oberg plan with her costume studio and his workshop.

    Oberg Construction Note: Since the Oberg house is built on a slope, the back of the basement is exposed to outside air and is not surrounded by soil like the front. And since outside air experiences greater temperature extremes than the soil mass, the builders compensated for this by installing an extra thick layer of foam board along the backside of the basement.

    In the garage, where an air seal wasn't needed, Brad Oberg decided to use the traditional fiberglass batt insulation to save some money.

    On the interior ceilings and walls of the home a new fiberglass batt insulation called "QuietZone®" was used primarily as a sound barrier.

    Note: Some builders use multiple layers of insulation on the interior walls to deaden sound, but this new material is an alternate — and feel better — choice.

    On the wall between the media room and the great room, Brad Oberg (homeowner) decided to supplement the QuietZone insulation by having the workers install special wall studs that have a built-in spring, which isolates the inside part of the wall framing from the exterior. When the stud vibrates from the noise, it's protected and the sound doesn't penetrate the other room.

    The original plan for insulating the house was an experimental combination of spray foam and fiberglass batt insulation, which we've documented earlier. The spray foam acts as an air barrier and the fiberglass batts as the thermal barrier, but the installers ran into some problems with this plan. The spray foam was applied a bit thick so the fiberglass pieces of insulation weren't fitting well. They were going beyond the drywall studs. The fiberglass had to be peeled in order to fit properly. In some places it was even difficult to get a staple to stick. It quickly became apparent that the combination of insulation wasn't working. In some parts of the house the insulation was bulging so much that no way drywall alone would be able to contain the material.

    Troubleshooting Solution

    After much discussion, the homeowners and site supervisor decided to remove the fiberglass batt insulation and have the stud cavities (standard 2" x 4"s) filled "entirely" with the Icynene expanding foam, which means there was a delay because the foam-spray installers had to be called back to the site.