Live And Dead Roof Loads In Residential Design

The bottom line is that the irc requires you to design the roof structure to the greater roof load and in my region that s the ground snow load.

Live and dead roof loads in residential design.

On a roof with a slope greater than 4 to 12 the live load limit is typically adjusted downward from 20 psf to 15 psf to allow for the relatively greater dead load on the steeper roof. 3 3 dead loads dead loads consist of the permanent construction material loads comprising the roof floor wall and foundation systems including claddings finishes and fixed equipment. Dead loads cont d typical weights of horizontal systems roof construction asphalt shingles 15 psf pounds per sq. Unlike stiffness live loads and dead loads are added together to determine minimum design values for strength.

The load is not shared equally by the supporting structure. Foot ceiling construction gypsum sheetrock finish 10psf floor construction carpet or vinyl 10 psf hardwood floor 12 psf ceramic tile 15 psf. Light frame 2x12 wood floor with 3 4 inch wood structural panel sheathing and 1 2 inch gypsum board ceiling without 1 2 inch gypsum board subtract 2 psf. D dead load l live load l r live roof load w wind load s snow load e earthquake load r rainwater load or ice water load t effect of material temperature h hydraulic loads from soil f hydraulic loads from fluids.

In my region on cape cod we have a ground snow load design of 25 psf which is a greater design load than the live load 12 psf to 20 psf over an entire roof system. The values for dead loads in table 3 2 are for commonly used materials and constructions in light frame residential buildings. Dead loads consist of the permanent construction material loads comprising the roof floor wall and foundation systems including claddings finishes and fixed equipment. Live and dead loads listed in the building code for roofs and floors are approximations of distributed loads.

The values for dead loads in table 3 2 are for commonly used materials and constructions in light frame residential buildings. To determine the dead load value for a given floor or roof system the weight of all permanently installed materials in a given component are added together.