Sold under many names
New-construction window
A window with a nailing fin, meant to be installed with the exterior cladding open so it can be fully flashed into the wall — as on a new build or a full tear-out.
What it means for you
The distinction that decides how watertight, and how disruptive, your job is. A finned new-construction install with proper flashing is the gold standard for water management, but it means removing siding; most NC replacements instead use a finless insert into the existing opening.
Where you'll see it
New builds, additions, and full-frame replacements where siding comes off.
Also sold as: nail-fin window
Related terms
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