20 Feet Roof Beams

Continuing on from part 3.

20 feet roof beams. Need to span 18 feet with roof load above. Three 2x10 s or 12 s is not enough. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

In the example the beam spans the 10 foot width of the roof. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. Beams of more than one ply must be fastened together with either nails or bolts. Minimum roof loading is 20 lb sq.

L stands for the span of the beam in feet. Better design with truss 2 feet deep or more depending on snow load. A truss joist wood i beam is not enough. Almost any wood will do the same geometry of beam or truss is the important thing.

For the initial calculation f can be estimated at 1 000. Staggered pattern with at least a 3 x 120 nail. You need an engineered glu lam 5 1 4 wide and 24 tall. Ordinary nail assembly installs as easily as ordinary lumber.

F stands for the beam s fiber strength in bending which depends on the species of wood. Tables providing size selections for various beam spans and loading combinations for southern pine dimension lumber and southern pine glued laminated timber are available for the following applications. Here we have a wood framed gable roof. Lvl is ideal for floor beams garage doors window and door headers and ridge and hip beams.

Multiple pieces of boise versa lam laminated veneer lumber can be assembled for greater thicknesses that can carry even heavier loads across even longer spans. Removing load bearing wall. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. If smaller beam will sag ugly.

The tables below give maximum spans for rafters and beams. Ranch style house built in 1961 has 2x6 roof joist and 2x6 cieling joist. For a 20 foot span wood beam needs to be minimum 18 inches deep. The total load is 4 000 pounds.

Let s consider a basic gable wood roof framing design. Feet more in presence of snow. The figures are based on quality materials. We have learned from our experience to use at least a 3 1 4 x 131 groove shank nail in a column of four every foot apart down the laminate.

The 2012 irc code calls for a minimum of a 32 o c.