Standard Roof Truss Angles

The truss is a framework consisting of rafters posts and struts which supports your roof.

Standard roof truss angles.

The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. If the overhang exceeds 2 5 feet we will need to use a larger top chord for the overhang typically a 2 6 top chord for the truss. This is useful because sometime you may need to cut a bevel with your circular saw that is not calibrated using roof pitch style this setting on circular saws is calibrated in degrees. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.

A 4 12 is a roof slope that rises by 4 inches for every 12 inches across. Pitches of less than 2 12 are considered flat roofs even though they may be very slightly angled. On blue prints architects engineers usually display the pitch of a roof in the format shown on the image where number 4 represents a rise and number 12 represents a length. A standard overhang is 16 24 inches but the overhang can be any length you wish.

Usually average roof pitch is determined using the same roof length method. This means if a roof rises 4 in the length of 12 your roof pitch would be 4 12 or 18 43 degrees. This forms an angle of 18 5 between the horizontal section and the roof and creates a gentle incline that is seen as a midpoint between a low pitch and medium pitch roof. A truss with the same pitch and heel on both sides and a peak at the center is called a common truss.

It s often used for sheds garages or extension of an existing roof. As we will see below there are several different types of designs and this will impact the angles and designs of the overall truss. Angle the angle of a roof is the same as the roof s slope except instead of being represented as x 12 it is represented in degrees. The most commonly used roof pitches fall in a range between 4 12 and 9 12.

Pitches lower than 4 12 have a slight angle and they are defined as low slope roofs. Pitches above 9 12 are very highly angled and are designated steep slope roofs. We can also build a cantilever for the overhang which is where the bottom chord of the truss continues beyond the wall. A mono truss roof allows for more sunlight and visual space proper drainage and relatively cheaper.

Greek says one must keep rafter length in range of 1 9 to 1 7 th of span but as per roman style the standard dimensions are kept about 1 3 to 2 9 th of span with an angle of 23 to 24 degree. Commonly it is 3 4 th of span as per gothic rafter must be equal to span.