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it's simple
Posted by tom on September 16th, 2003 11:05 AM
In reply to Cutting Shed Roof Rafters by Ken Tashjy on September 16th, 2003 08:47 AM [Go to top of thread]
Method 1:
6/12 is a 45 degree angle, without going into the basic trigonometry here's the answer:
Take the total length of the roof span, divide it by 2.
Take this length and divide it by the square root of 2 (square root of 2 is 1.414 or multiply by 0.707), this is the length of the "pitched" portion of the roof from dead center ridge to wall edge.
Remember though, this does not take the ridge board or "tails" into account, if you want a tail you have to add that to the length. If you're putting in a ridge board, subtract 1/2 the width of the ridge board (eg: if using a 2X10 ridge board you use 1/2 it's width or .875 -- they're not really 2 inches.)
Method 2:
The fastest and easiest way to do it on a sawhorse is using a carpenters square. Using the center of your roof board as the measuring point, put the 6 inch mark of the tail of the square dead center on the far left center, put the tongue's 12' mark (other end) dead center - mark it. Now continue this until you have moved exactly as many feet as you have in 1/2 the horizontal span.
The second method is simple and accurate, but hard to explain without a picture. Was this post helpful? Yes: or No:
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