How To Measure Roof Truss Size

There are several variables to consider when determining the proper rafter size.

How to measure roof truss size.

Outside of the u s a degree angle is typically used. Use a level square and measuring tape. Next you will need to use a roofing materials calculator. The truss is a framework consisting of rafters posts and struts which supports your roof.

Equation a2 b2 c2. Hammer a nail in place to hook your measuring tape and space out the subsequent trusses every 2 feet or other designated spacing. These are the base boards of your roof truss. Converting that to feet and inches the length of the top chord is 10 feet 3 16 inch.

Divide this number by 2. C rafter length. Calculate the length of the top chord with the formula h sqrt r 2 s 2 where h is the length of the top chord measuring from either side of the chord from plumb cut to plumb cut. Pitch measurement method 2 2.

For example h sqrt 3 167 2 9 5 2 10 014 feet. Trusses are generally secured 24. This sizing guide for roof rafters will help determine what you need for your small project. For example a roof with a span of 20 ft and a rise of 7 feet needs rafters that are the square root of 400 49 21 2 feet.

If this distance measures 4 inches you have a 4 in 12 pitch. Already having the rise will make it easy to determine the rafter length by loading the numbers into the equation chart. Divide the length of the roof by two to determine how many trusses are needed. For instance a 7 12 roof pitch means that the roof rises 7 inches for every 12 horizontal inches.

Obtain the height of the gable by finding the difference in height between the top of the roof and the top of the structure. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. Measure out 5 to 6 trusses at a time. How to measure roof trusses.

8 inches and you have an 8 in 12 pitch. Get the width of the structure you want to roof by measuring across the tops of the walls. Pull a tape measure along the top plate of the house to determine the length of. On a ladder beside the roof place the level a foot or so up the roof hold it level and measure from the 12 inch mark on the level s bottom straight down to 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. Simply input the surface area of the roof choose from one of the available options and you will get your first roofing estimate. Set two ladders at each end of the area to be measured.