Over Spanning Of Roof

Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.

Over spanning of roof.

2 are indicated below. In snowy areas your roof should be at least 10 12 40 to allow snow to shed while the safest roof pitch in very windy areas is between 4 12 6 12 18 5 26 5. Snow and rain which usually pile up on a flat roof run off the slanted roof thus prolonging the lifespan of the roof. 1 ft 0 3048 m.

Since pitch is the rise over a 12 inch run divide the run by 12 to get the multiplier in this case 120 12 10. The cheapest option would be to leave the old roof in place and place the new rafters over the existing roof. The pitch fraction represents a certain amount of vertical rise over the entire span. Make sure to document the number of chimneys skylights or other obstructions and include dormers in your measurements.

The best case scenario for an overlay is sound decking. The total run is the distance from the peak to the edge of the roof which in this case is the total width divided in half which is equal to 10 feet or 120 inches. Live load is weight of furniture wind snow and more. And a roof with no sidewalls where flashing is needed to tie in the roofing material to the exterior walls of the home.

Dead load weight of structure and fixed loads 15 lbs ft 2. 1 psf lb f ft 2 47 88 n m 2. 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. A roof that rises 8 feet over a 24 foot span was said to have a 1 to 3 pitch.

If the rise is 4 feet over a 24 foot span then the roof pitch was said to be 1 to 6 the pitch can be expressed numerically as a fraction. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. The tables below give maximum spans for rafters and beams. First measure the length and width of each surface on the roof then multiply these values to get the square footage of that surface.

Use premade roof trusses premade roofing trusses will be easier and take less time than installing a stick built roof. No previous or existing leaks. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.