The Ultimate Roofing Square Makes Pitched Roof Construction Easy
Using the Ultimate Roofing Square from Essential Carpenters Tools is as easy as 1, 2, 3...
1/ Set the roofing square to the required pitch and lock into position
2/ Calculate the Half Span by measuring the overall and dividing by 2 (less half the thickness of the ridge board)
3/ Look up the Half Span on the supplied Roofing Chart to give you the necessary 'multiplier value' (see 'Roofing Chart')
4/ Calculate the Rafter Set out Length (RSL) by multiplying the Half Span by the multiplier value from the supplied Roofing Chart
5/ With the roofing square fully assembled, (sliding arm in place) slide it until you have approximately a third of the depth of the rafter and lock
6/ Measuring from the plumb cut, mark the RSL and place the Ultimate Roofing Square on the face of the rafter and mark the birds mouth cut out
Repeat until all the rafters are complete. Happy roofing....
Worked example - if Roof Pitch is 40º and Half Span is 2500 cm, then:
1/ the Essential Carpenters Roofing Chart says the Multiplier Value for a 40º roof is 1.305
2/ the Rafter Set out Length (RSL) is calculated simply as - 2500 (the Half Span) X 1.305 (the Multiplier Value from Roofing Chart) = 3262 cm