Roof Live And Dead Loads

Victor staley a building official in the town of brewster mass responds.

Roof live and dead loads.

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. The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated. Loads used in design load equations are given letters by type. In short the dead load of a structure comprises its completed weight usually measured in pounds per square foot before it goes into service.

Roof live load reduction. D estimated mean dead weight of the construction. The floors walls roof columns stairs permanent equipment and any fixed decor constitute a static load that normally doesn t change over the life of the building. Where d is floor dead load.

Roof live load may be reduced by the following equation. D dead load l live load l. As a result the live load dead load and distribution of forces are different. Live loads keep on changing from time to time.

How do they differ. L design floor live load. Roof dead load framing sheathing asphalt shingles insulation drywall 10 exterior wall 2 4 framing sheathing siding insulation drywall 10 floor joist sheathing carpeting drywall 10 concrete wall 8 in. Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states.

Live loads are also called as imposed loads. Lr maximum roof live load anticipated. R 1 1 for a t less than or equal to 200 psf r 1 1 2 0 001 a t for between 200 psf and 600 psf. L r l o r 1 r 2.

From the general concept of load comes two major categories. Where l r shall not be less than 12 psf and not more than 20 psf. Thick 125 12 in. Thick 100 10 in.

H design lateral pressure for soil condition type. This issue of live load vs. 1the load combinations and factors are intended to apply to nominal design loads defined as follows. 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.