The second span table is the same as the first. The first span table is for roofs where the ceiling is not attached to the rafters (with no snow load), a live load of 20 Psf, a dead load of 20 Psf, and a deflection limit of L/180. If it has been installed then you must fit the clip to the beams rather than the other way around. Rafters with ceiling not attached to rafters, ground snow load 50 Psf, dead load 20 Psf, deflection limit L/180. These logs are approximately 5-6' in diameter and are placed about every 2 1/2 - 3 feet apart. The existing design has logs that extend from the outside perimeter of the building to the peak of the roof. Inspectors may find rafter ties installed above ceiling joists as framing members every 4 feet running above the ceiling joists connecting opposing rafters where ceiling joists run. A rafter tie is the lowest chord of a simple triangular roof truss. This is only necessary if the diagonal beam going towards the apex of the roof has not been installed yet. Exterior wall to the peak of the roof is about 8-9 feet. Roof ridges that droop are a telltale sign that the roof structure lacks rafter ties. FIGURE R802.5.1 BRACED RAFTER CONSTRUCTION TABLE R802.5. Position the diagonal beam so it is sitting in the open ‘U’ space. H R = Height of roof ridge measured vertically above the top of the rafter support walls. H C = Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. Note: Where ceiling joist s run perpendicular to the rafter, rafter ties shall be installed in accordance with Section R802.3.1. (Uninhabitable attics with limited storage, live load = 20 psf, L/Δ = 240) CEILING JOIST SPACING (inches)įor SI: 1 inch = 25.4 mm, 1 foot = 305 mm, 1 degree = 0.018 rad. (Uninhabitable attics without storage, live load= 10 psf, L/Δ = 240) CEILING JOIST SPACING (inches)Ĭheck sources for availability of lumber in lengths greater than 20 feet.įor SI: 1 inch= 25.4 mm, 1 foot= 304.8 mm, 1 pound per square foot= 0.0479 kPa.Ī. Shall be in accordance with Tables R802.4(1) and R802.4(2).įor other grades and species and for other loading conditions,ĬEILING JOIST SPANS FOR COMMON LUMBER SPECIES
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