Lumber yard prices would be slightly higher, but supposedly be better quality wood.įor special order pricing (24′ boards or engineered wood rafters) contact local building material suppliers or lumber yards. Longer size boards are NOT available.Ģ) If you need a rafter longer than 24 feet, you will have to use engineered wood rafters.įor pricing we used Home Depot online prices, which are comparable to Lowe’s prices for the same size boards. If your rafter length is calculated to be longer than 20 feet, then there are two options for you:ġ) Most lumber yards and building materials suppliers sell an actual 2″ x 12″ by 24 feet boards for $45-55 each. This tool is designed for lumber length of up-to 20 feet, which can be commonly purchases at local home improvement stores and lumber yards. Limitations Of The Rafter Length Calculator Sizes are NOMINAL, which means that a 2×8 is actually 1.75″ x 7.25″ board. These are “retail” prices and if you have an account and are working with an outside sales person, you can typically get 3-7% discount. Prices below were sourced from National Lumber in Newton, MA. There is no “board price”, meaning that a 24′ 2×10″ board will cost the same per foot as 32′ 2×10″ board. LVL prices are calculated PER foot PER size. The calculator will automatically switch your board from PINE to LVL when you exceed 20 feet long threshold on rafter length. If you need longer LVL, they can be custom ordered. LVLs come in 24′, 28′, 30′ and 32′ standard lengths. LVL is VERY expensive, but solves the limitation of 20 feet, in a common pine board.
If you need rafters that are 20′ 1″ or longer, you will need an LVL (Laminated Veneer Lumber) engineered rafter board, which is this yellow color plywood-like board made for structural purposes. Rafters LONGER than 20 feet: Home improvement stores DO NOT sell pine boards longer than 20 feet. Lumber size/ width (2×8″, 2×10″ or 2×12″ boards) will be used to estimate cost of each rafter, as well as total cost (excluding local sales tax). Rafter spacing (and roof length) will be used to determine quantity of rafters needed for your project. If your roof pitch is in degrees, use our roof pitch calc to convert degrees to “pitch” value. Example: If your roof rises 5″ for every 12″ of run, enter 5 as roof pitch. Enter desired overhang length – this will affect your rafter length and lumber needed for the job.ģ) Enter roof pitch / slope: Roof pitch is the value of roof rise over roof run, using 12 as the base for roof run. Width or Span is the gable side of the roof, which is used in calculating rafter length and cost.Ģ) Enter overhang length: Most houses have overhangs (soffits) which are needed to protect the house exterior walls and foundation from water run-off from the roof. It is excellent for framers, builder, contractors, GC’s and architects and will be helpful in planning new construction projects.ġ) Enter house footprint: Length is the roof eave ( gutter) side. Use the diagram on the right to correctly enter your roof dimensions – this will help you calculate board length more accurately.
Shed roof rafter span calculator code#
To calculate maximum rafter spans using different design criteria (load, snow load, spacing, grade, etc.), for these common lumber species, see the International Residential Code (IRC).
The above spans are based on American Softwood Lumber standard sizes. Rafters with ceiling not attached to rafters, ground snow load = 50 psf, dead load = 20 psf, deflection limit L/180 The following span table uses a moderate snow load of 50 psf, but yours could be more or less. Consult your local building code authority to determine the snow load in your area. Note: Snow load can be very specific to the actual location of a structure. Rafter Span Tables Rafters with ceiling not attached to rafters, live load = 20 psf, dead load = 20 psf, deflection limit L/180 The braces need to be supported by a bearing wall, as shown in the diagram above.Įxample: In the rafter span table below, the highlighted cell (13-0), indicates that 2" x 8" Douglas Fir rafter, with a grade of #2, spaced 24" apart, can have a maximum span of 13 feet - 0 inches (13-0) if designed for a live load of 20 psf, and dead load of 20 psf. Note also that you can break up the span of a rafter by adding a purlin and bracing to the underside. When calculating the maximum span of a rafter, use the horizontal distance between two vertical supports.
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