Would it help to replace the weather stripping around our window sashes? The old ones are flat and brittle.

Asked by Ken Ray
Cary, NC

Newer windows from Anderson and Pella have soft flexible bulb weather stripping on the top, middle (where sashes meet) and bottom of Bottom sash where it meets the sill. I can buy this and instal for about $55 for my 28 windows.


Lucas Johnson

Answered by Lucas Johnson

Seattle, WA

Cascadia Consulting Group

July 9, 2012

The answer depends on your goals and the age of your house and windows.

Please post back with more details about these items and I will respond again. However, please see below for some general considerations

Building science principles often show window upgrades are a final step in improving comfort, health, and/or efficiency in homes. This is because of three main things: 

  1. Windows are a relatively small % of the surface area of your home;
  2. The difference between high performance windows and normal windows isn't as significant as insulating attics/crawls/walls (and insulating is way cheaper); and
  3. You want some degree of air leakage in homes (to exchange stale air, potential pollutants, moisture, etc.) and windows are a great location for air leakage because they connect directly to outside.

Unless you install an energy recovery ventilator (or other whole house ventilation), then after properly sealing your attic/crawl, you will need leaky windows to maintain sufficient air exchange.


For more information:

Read "Is there a way I can improve the sealing around my windows to increase their efficiency?" a Q&A answered by Danny Kelly.

Tagged In: energy efficient window

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