Window Order Size to Rough Opening (R/O)

DIY - If Your Bound & Determined
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Wayne
Posts: 2
Joined: Tue Jun 27, 2006 10:22 pm

Window Order Size to Rough Opening (R/O)

#1 Post by Wayne »

Which one is the correct order size with existing wood frame?
A. R/O - 1/2 inch
B. R/O - 1/4 inch

Certainteed web site indicates the deduction is 1/2 inch, but some contractors are saying 1/4 inch.

E-Z
Posts: 104
Joined: Thu Oct 07, 2004 12:13 pm
Location: North San Francisco Bay Area

#2 Post by E-Z »

The smart thing is to follow manufacturer instructions regardless of " contractors" opinions. My experience for a nail on application deduct 1/2 inch from the rough opening. For a retrofit install deduct 1/4 inch from the net size

Good Luck

E-Z
E-z
E-z Windows

House Doctor
Posts: 11
Joined: Sat Aug 26, 2006 7:38 pm

#3 Post by House Doctor »

Here's the key: how out-of-square is your EXISTING frame or RO? ALWAYS Deduct the amount out-of-square PLUS and extra 1/8" both ways. To find out-of-square take the greatest of these differences: The diagonal from top left to bottom right, minus the diagonal from top right to bottom left. Then measure the height left, center, and right and subtract the shortest from the tallest. Then measure the width top, middle, and bottom and subtract the shortest from the longest. The GREATEST of these 3 sets of numbers should have 1/8" added to it to determine the difference between your existing SO and the new make size. If this isn't clear, you shouldn't be doing this yourself--get someone who knows what they're doing or you'll just be spending money and not improving your energy efficency or your home's value. Good Luck!

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