Backer rod
A foam cord pressed into a deep gap around the window before sealant, so the caulk bonds to two sides at the right depth instead of filling a bottomless joint.
What it means for you
The detail between a lasting exterior seal and caulk that cracks in a year. When the perimeter gap is deeper than about half an inch, backer rod is the right way to do it — and caulk should never be smeared over the weep holes.
Where you'll see it
In the exterior sealing step; not usually itemized.
Related terms
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