Raising Shed Roof Rafters on a Beam

Raising a Shed Roof rafter on a Beam

In a previous blog we talked about how to figure the length of a shed roof rafter if it lays onto another roof and in another separate blog we talked about how to drop the shed roof rafter on a beam. This time we will explain the procedure for figuring the length of a shed roof rafter if it is raised on a beam. Actually the procedure is the exact opposite of drop beam method. So here goes. The amount the beam is raised divided by the rise of the high pitched roof = run in feet to add to the original run. Then just multiply the decimal portion by 12 to get inches. For example...

Amount beam is raised = 3.5"

High pitched roof =

3.5/7 = .5

.5 x 12 = 6"

original run + 6" = new run

Then enter the new run into the formula on this page to figure the length of the shed roof rafter.

Remember that since the math of all this is straight lines and that rafters have depth then the depth of the rafter ( I call it HAP for height above plate) at the plate must be accounted for or kept the same when laying out, measuring and cutting the rafters. Study the image below.

    You can see that the theoretical distance " a " changes making the run and the shed roof rafter longer when placed on a raised beam. Click image to enlarge into a new window.

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