Roof Load Bearing Rough Timber

Deck exterior and interior load bearing walls beams girders posts and floor framing.

Roof load bearing rough timber. A clay tiled roof may have a dead load. Shear walls or steel moment frames in homes with large windows or other large openings provide the strength to resist lateral loads. Roof trusses support a roof s weight by transferring the weight load downward and outward to the building s bearing walls. Residential structures framing systems typically consist of the roof structure that supports the roof.

They do this by means of top chords which are sloping members that extend from the peak of the roof to the top of the exterior walls at the eaves. Roof and wall sheathing gravity and wind loads floor diaphragms and shear walls in plane lateral overturninand g loads 6 notes. Headers girders joists interior load bearing walls and columns footings gravity loads exterior load bearing walls and columns gravity and transverse lateral load 3 roof rafters trusses and beams. If our example roof has only one beam it must carry half of the total load or 4 000 pounds.

Spacing will vary be design and roof load but usually 24 on center or less. The load increases with the use of heavier roofing material. May be attached above the trusses on edge or flat or between the trusses using post frame anchors or joist hangers. If one side of the roof is supported by the house and the other side is supported by the beam divide the total load by two as the beam is only supporting half of the roof.

A roof is composed mainly of two parts the cladding or external material and the internal support structure which holds it up. Sawn lumber limits design potential and in some cases just doesn t work. The dead load of a typical asphalt shingled wood framed roof is about 15 pounds per square foot. You can t beat sawn lumber for most small window headers but as spans and loads increase stronger materials are a better choice.

Roof purlins are 2x4 2x6 or 2x8 lumber that spans between the trusses to provide framing for metal roofing or roof sheathing. If there is also a beam in the middle of the roof divide the total load by three. The amount of weight the internal support structure can carry without the roof collapsing can be described as its load bearing capacity. Depending on how wide the home is you can divide the total length in feet by two to determine how many trusses will be needed.

Determine how many rafters you ll need for the roof.