How the Building Envelope and Insulation Go Hand in Hand to Protect Your Home

March 18, 2015
Ross and Witmer

To protect your home and make it as energy efficient as possible, it’s necessary to understand your home from the standpoint of a building structure with multiple systems. While your home’s envelope protects you and loved ones from the elements, the systems that comprise the envelope, such as roofing and walls, need protection in return. Keep reading to learn how the building envelope and insulation work together to protect your home.

Your Home’s Envelope

A home’s building envelope consists of all the materials and devices that separate the conditioned living spaces from the unconditioned spaces and the elements outside the home. The primary components of the building envelope include the roofing system, foundation, floors, walls and the ceiling insulation barrier.

The quality of a home’s construction and upkeep determine how comfortable and efficient the home will be. Older homes tend to be less efficient than newly-constructed homes using the latest energy-efficient building materials and technologies. The building envelope and insulation work to keep conditioned air in the living spaces by preventing the transfer of heat energy from a warmer place to a cooler place. This means adequate insulation is important for all seasons.

Attic Insulation

The building envelope and insulation in the attic must contend with the chimney effect of warmer air rising above cooler air. This can be an expensive and uncomfortable problem if attic insulation isn’t up to par. The federal Energy Star program suggests an attic insulation R-value of up to R-60. R-value indicates a material’s resistance to heat transfer.

The transfer of heat to the attic during the heating months can cause ice dams on the roof, which can lead to water leaks. During the cooling months, heat from the attic can transfer through the ceiling and increase cooling bills.

Fiberglass and cellulose are popular insulation materials to help prevent damage to the building envelope and insulation. Depending on the density and R-value of the insulation, one inch of fiberglass or cellulose is approximately R-3 to R-4.

Following are guidelines to insulating the attic:

  • Unconditioned attic: Attic insulation should be higher than the joists. Check existing insulation for mold and water damage. Damaged insulation should be replaced. Use lighter insulation materials if adding to existing insulation.
  • Attic access door: Don’t forget to insulate the back of the attic access door. Seal the perimeter with foam weatherstripping to prevent air bypass.
  • Finished attic rooms: Insulate floors and ceilings with unconditioned spaces located above. Insulate between studs.

Wall Insulation

The home’s walls can potentially waste a lot of energy and cause drafts from room to room. Sun-facing walls can experience tremendous heat gain during the cooling months, and shaded walls can lose heat during the heating months. To check to see if your walls are insulated, remove an electrical outlet plate on each wall and look inside. Insulating existing walls is generally a job for a professional. However, if wall cavities open into the attic, you can install loose-fill fiberglass or cellulose.

If your home has an attached garage, make sure you check the shared wall for insulation. If the shared wall is unfinished, it’s in your best interest for efficiency, comfort and safety to insulate the wall, finish and seal it. Foundation walls in conditioned basements and above-ground foundation walls should be insulated with rigid foam board. Window treatments may be used to minimize heat gain/loss. Shades, curtains, shutters and storm panels are practical upgrades.

Floor System

Some of the signs of a poorly insulated floor are cold floors, room drafts and high energy bills. All floors above unconditioned spaces should be insulated. Basements and crawl spaces often harbor moisture. It’s not recommended to use fiberglass and other insulating materials that are prone to mold and moisture damage. Rigid foam board is a good option for insulating beneath the floors. If you’re considering sealing your basement or crawl space, use closed-cell polyurethane for the job.

Ductwork Insulation

Ductwork in unconditioned spaces of your Charlotte home should be considered an extension of the living spaces because they channel conditioned air. Therefore, all ducts outside the insulation barrier should be insulated. Uninsulated air ducts can lose as much as 20 percent energy, which increases energy bills and makes your heating and cooling systems work harder. You may insulate ductwork with rigid foam board. Ducts in the attic may also be insulated with fiberglass rolls or batts.

Learn more about Ross & Witmer’s services to protection your home’s building envelope and insulation, or give us a call today at 704-392-6188 to schedule an appointment for your Charlotte area home!

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