Calculate roof decking with incredible precision with this free app. Based on the knowledge of the roof pitch and the length of one known side.
Works with any pitch or combination of pitches on 4′ x 8′ sheets of plywood. You should have at least some experience with decking roofs before going any further. There are two distinct traditional methods.
The most basic is simply to lay the decking to hang over the hip and then pop a line on it according to its position on the hip. Then saw it as carefully as possible as this can be extremely risky. The sawdust generated will collect on your walking surface and can make traction virtually zero.
The other way is to measure the length for the top and measure the length for the bottom. There is always one side that can be readily measured, but the other side has to ne determined by a straightedge of some sort.
Install now:
Roof decking calculator
Open app
Click on Menu in the top left.
Select Roof decking
Click on Roof decking towards the bottom.
Active pitch
Enter the roof pitch for the side where the decking goes.
Side pitch
Enter the roof pitch for the adjacent side. Most of the time, this is the same as the active pitch.
Width
For sheets with a long point and a short point, enter 48, for triangle pieces see the example below.
Known side
Enter the length for the long point or the short point, then click plus or minus respectively.
Result
The result for the unknown side always in inches.
Triangle pieces
Active pitch
Enter the roof pitch for the side where the decking goes.
Side pitch
Enter the roof pitch for the adjacent side. Most of the time, this is the same as the active pitch.
Width
Enter the length up the rafter, then click equals.
Result
This is the length.