Rafter Sizes For A Pitched Roof

Typical tiled roof with plasterboard on underside of rafters.

Rafter sizes for a pitched roof.

Input the rafter span on the flat eave overhang and pitch of the roof. 45 get exact slope using our roof pitch calculator. Automatically calculate suitable rafter sizes enter a specific rafter size 1 3 timber strength class c16 cost effective for most applications. 1 1543 x 1 610 1 858m.

Rafter stock size calculator. 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. This calculator is to be used as an estimating tool only. Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings.

For pitched roofs flat roofs and ceiling joists. Rafter length using angle v r 2cos a rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch use our online rafter length calculator to quickly compute the length of the shed roof rafter by entering the measurements of overhead length of roof span pitch or angle. For roofs that won t experience heavy snow loads a gable roof can span up to 22 with 2 4 rafters. Surveyors span tables for designing roof rafters.

As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes. For roofs that will experience heavy snow or wind and will span the same distance use 2 6 rafters. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. Area span on the flat.

Click the button to calculate the stock size needed for this job. All we do now is use a calculator to multiply 1 610 by the measurement in the book. Rafter stock size calculator. You can use either 2 6 or 2 4 rafters for roofs with a 3 12 pitch or greater but it depends on the overall size of your shed.

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. Pitch rise run in approx slope degrees 1 12. Click the button to calculate the stock size needed for this job. The length of rafter per meter of run is 1 1543.