After they re up you can snap a line to mark and trim the tails in a nice straight line to make up for any ridge warp or marking cutting and fixing errors.
Gable roof size.
Gable roof a gable roof has two opposite sides with equal slopes and equal spans that meet in the center of the roof at the ridge.
Use the saltbox roof to calculate a two sided roof with different slopes spans and or overhangs for each side of the roof.
In the united states a run of 12 inches 1 foot is used and pitch is measured as the rise of the roof over 12 inches.
Measure and mark the square footage of each triangular section carefully as these tend to differ in size.
Keep in mind that the average size of a roof is 1 700 square feet so your total will likely be 10 higher or lower than this figure.
Total roof width with rake overhangs.
Length from ridge to eave.
Measure out horizontally 12 one foot from the gable end sloping trim to a point along horizontal siding or use your level to make a mark that is level horizontally measured out 12 from the sloped gable trim or roof edge.
Another option are 2 x 8 rafters spaced 24 inches o c.
Check that your footage measurements are within this range so you can start off on the right foot.
Total rafter lumber length.
Gable roof framing calculator plan diagram with full dimensions for a good straight fascia add an extra inch or 2 to the tails of all your rafters total length.
The table states that 2 x 6 rafters spaced 16 inches on center o c can span a maximum distance of 13 feet 5 inches.
Rafter plumb cut depth.
If you have a roof section that s 30 feet 9 1 m long and 12 feet 3 7 m high multiplying those dimensions would give you an area of 180 square feet 17 m 2.
Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.
For instance a 7 12 roof pitch means that the roof rises 7 inches for every 12 horizontal inches.
10 add up the areas of each section to get your total square footage.
In making your choice consider how you will insulate your insulate your roof.