Ensure Proper Installation of New Windows

The Importance of Quality Window Installation

Quite simply, windows are only as good as their installation. Proper installation is necessary for optimal window performance, to ensure an airtight fit and avoid water leakage. Always follow manufacturers installation guidelines and use trained professionals for window installation. Proper installation will:

  • Protect from water damage. Windows should form a continuous water barrier where they meet the wall. With improper installation, water may penetrate and cause damage—often unseen—in the wall.
  • Limit air leakage. Windows must complement the wall’s air barrier. Even tiny cracks around the window frame can lead to substantial heat loss unless properly sealed.
  • Prevent condensation. Windows must complement the wall’s vapor barrier to prevent water vapor from passing around a window frame. If vapor condenses on cold surfaces between the frame and the wall, rot or other damage may follow.
  • Reduce sound intrusion. Proper installation will help with sound transmission issues.

Due to these potential issues, windows should be installed by skilled and experienced individuals.

Finding Quality Installers

The first place to inquire about quality installers is the manufacturer from whom you are purchasing the windows. Manufacturers may have recommendations of in-house or 3rd party installers or installation certification programs.

There are standards for proper window installation, and installers are well advised to follow these along with the manufacturer’s product-specific installation requirements. The most prominent of these standards is ASTM Standard E 2112. Trained installers are likely to be familiar with this standard. Window manufacturers may have training and certification programs for installers of their own products. Installers may also be certified by nationwide programs such as:

  • InstallationMasters™: www.installationmastersusa.com includes a directory of certified installers in the United States.
  • WindowWise National Certification Program: www.windowwise.com includes a directory of certified installers in Canada.

Some Installation Basics

1. Always follow manufacturer’s installation guidelines and specifications.

2. Install level, plumb, and square.

3. Install water tight: water must be prevented from penetrating behind the water control system of the wall. Different techniques apply to different water control systems:

  • Surface barrier system (masonry, concrete or brick with no cavities): the window frame must be carefully joined with the surface barrier because no water must penetrate this barrier;
  • Drainage membrane system (house wrap or building paper behind exterior cladding material such as siding, brick veneer, or stucco): the window must be installed so that any water that gets behind the cladding is drained down and out over the drainage membrane.

4. Allow movement and thermal expansion (¼” to ½ tolerance around the frame)

5. Seal it up: Maintain the integrity of any air barrier and vapor retarder used in the wall system and seal all gaps around the window frame with caulk. Insulate all voids with foam or batt, but only use low-expansion foam to avoid pressure that could distort the window frame.

Caring for your Installed Products

The American Architectural Manufacturers Association (AAMA) has put together resources for proper care and maintenance for windows, doors, and skylights. Caring for Your Windows, Doors and Skylights can be found on their website.

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provides unbiased information and education to the public on the energy efficiency, technical, and human considerations that influence window selection and use. The EWC collaborates with allied organizations, educational institutions, and government agencies that promote energy efficiency in residential windows. We do not sell, service, install, or recommend products, or endorse manufacturers. Descriptions and specifications of the products in the Window Selection Tool are provided by the manufacturer. The EWC is not liable for any manufacturing defects or inaccurate product descriptions and specifications and does not guarantee the performance of NFRC-certified windows, doors, and skylights.

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