Air Infiltration Troubleshooting

What Is Air Infiltration?

Air infiltration is a natural occurrence caused by pressure differences inside and outside of your home. There are many areas where air can leak into your home, including window frames, walls, floors, outlets and more.

What Causes Air Infiltration?

The American Architectural Manufacturers’ Association notes that every home needs to breathe. Natural ventilation (a controlled air exchange) will occur in all windows and in all homes. But there are a few factors that may influence air infiltration:

• The style of window. Fixed, picture windows offer the most resistance to air infiltration. Operable windows, such as double hung and sliders, can experience more air infiltration because they have a moveable sash with sliding seals. Casement windows with multiple locking points and compression seals are the most air-resistant operable window.
• The location of the window. Where a window is located can impact air filtration. Windows that face stronger winds can have increased air infiltration, compared to those that are more sheltered.

Air Infiltration Reduction Tips

Below are some potential reasons why you may be experiencing air infiltration. Checking these are as may help you reduce air infiltration around your windows. You can also utilize our Air Infiltration Diagnostic Test Guide to help you visually examine your double and single hung windows for potential installation issues.

• Be sure your windows are properly closed and locked.
• Clean dirt and debris out of the weather stripping, which can reduce its effectiveness.
• Inspect the caulking around the interior and exterior trim and molding. Typically, missing or damaged caulk (dried up or shrunken) will allow air infiltration.
• Installation screws and jamb adjuster screw holes should be caulked and/or capped—depending on the style of the window.
• The windows should be installed plumb, level and square; if not, air could enter your home around the frame.
• If you have siding on your home’s exterior, ensure there is a tight seal up to the window.

Whistling windows, or a “humming” sound through the siding, can indicate an installation problem. If you suspect questionable installation, it’s a good idea to have the contractor who installed the windows inspect them to ensure the product was installed according to the manufacturer’s installation instructions.