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figuring square footage of roofs???? Post New Topic | Post Reply

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Craig Maturi
Posted: Apr 18, 2007 07:48 PM
figuring square footage of roofs????
does anyone know an easy formula to figuring out sq. ft. of underside of roof decks for the different pitches???
Posted: Apr 18, 2007 08:35 PM
An easy method that I always try to use is to count the sheets of plywood (5 sheets = 20'). That will get the "height" and then obviously just measure the length of the wall section. Dormers and valleys can be a little tricky, you just have to use some basic math.

Another method would be to find out how many square of shingles they used. If they used 22 square of shingles you know that they had 2200 square feet of roof to cover. This isn't too precise because they lose some in valleys and cutoffs, but again it gets you in the ballpark to compare.

Tim
Granite State Spray Foam Co.
Thomas Kasper
Posted: Apr 19, 2007 07:55 AM
Go buy a carpenter square that comes with a handy pocket book for rafter lengths. They have the charts for width of building and the pitch of roof = rafter length.
Edward Brassington
Posted: Apr 20, 2007 07:00 AM
The following chart is a pitch calculator for a straight forward roof. Hope this helps

Pitch
Multiply Flat Area By


3/12x1.031,
4/12x1.054,
5/12x1.083,
6/12x1.118,
7/12x1.158,
8/12x1.202,
9/12x1.250,
10/12x1.302,
11/12x1.357,
12/12x1.413,
Edward Brassington
Posted: Apr 20, 2007 07:00 AM
The following chart is a pitch calculator for a straight forward roof. Hope this helps

Pitch
Multiply Flat Area By


3-12x1.031,
4-12x1.054,
5-12x1.083,
6-12x1.118,
7-12x1.158,
8-12x1.202,
9-12x1.250,
10-12x1.302,
11-12x1.357,
12-12x1.413,

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