"We just wanted to tell you how pleased we are with the patio door that was installed and the Gutter Caps that were installed several weeks ago. The patio door looks great and we love the Gutter ... » more
- Harlan and Sandy Henzen of Davenport, Iowa


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Air-Leakage Rating

A measure of the rate of air-leakage around a window, door, or skylight in the presence of a specific pressure difference. It is expressed in units of cubic feet per minute per square foot of frame area (cfm/sq ft). Formerly expressed as cubic feet per minute per foot of window perimeter length (cfm/ft) but not now in use. The lower a window's air-leakage rating, the better its air tightness.

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