Live And Dead Roof Loads In Residential Design

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.

Live and dead roof loads in residential design.

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. The load is not shared equally by the supporting structure. 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. 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.

Loads used in design load equations are given letters by type. 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. 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. Unlike stiffness live loads and dead loads are added together to determine minimum design values for strength.

The values for dead loads in table 3 2 are for commonly used materials and constructions in light frame residential buildings. The values for dead loads in table 3 2 are for commonly used materials and constructions in light frame residential buildings. 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. Point loads occur when a weight is imposed on one spot in a structure like a column.

Live and dead loads listed in the building code for roofs and floors are approximations of distributed loads. Dead loads are given as nominal or asd level.