Lumber Size For Roof Truss

At the end of the day it doesn t matter.

Lumber size for roof truss.

Trusses must be designed for any special loading such as. 1 psf lb f ft 2 47 88 n m 2. They are designed at a 4 12 pitch to be spaced 2 foot on center. Pre manufactured stock trusses are constructed with spruce pine fir spf or southern yellow pine syp lumber.

For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. A 4 12 pitch means that the roof rises 4 inches for every 12 inches of run. 2x4f 2000psif 1100psie 1 8x10 2x6f 1750 psi f 950 psi f 1900 psi e 1 8x10. Gable room in attic trusses provide an economical way to add extra living space to your home or garage.

There s already been mention of using a prefab set up when appropriate and you can always attempt to negotiate a lower labor fee for larger projects. I hope this clears up the muddy water of truss design. Maximum and use lumber properties as follows. It is always better to have a large rafter rather than be concerned with a sagging roof.

Dead load weight of structure and fixed loads 15 lbs ft 2. The truss is a framework consisting of rafters posts and struts which supports your roof. Live load is weight of furniture wind snow and more. 2 are indicated below.

If the truss is designed in a way the engineer will approve it then it doesn t matter the lumber size that was used. The room size will vary depending on the width and slope of the truss. These trusses the meet building code criteria as specified by structural building components of america sbca and the truss plate institute tpi. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

1 ft 0 3048 m. A stick framed house used 20 643 board feet of lumber while a component framed house including roof trusses used only 15 052 board feet of lumber. Every truss designer has his own signature style. A gambrel room in attic truss also provides extra living space while giving your roof a barn like appearance.

One will like to use a 2 6 1 yellow pine with a certain mending plate where another will like to use a 2 4 msr 2400 with an extra web. Spaced sheathing or 1x boards may be reduced slightly. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. It is strong but shallow maximizing the use of lumber using available and ordinary lumber sizes.

That is 25 less lumber which means more money in your pocket as the builder and more money in the pocket of the homeowner.