Roof Live Load Requirements

An nahb proposal amended the 2015 ibc to restore the traditional 20psf roof live load requirement for porches patios or canopies on one and two family dwellings but the issue remains for multifamily buildings.

Roof live load requirements.

This modification makes two key changes. The load increases with the use of heavier roofing material. The north zone middle zone and the south zone are identified on the roof load zone map above. Chapter 3 design loads for residential buildings.

This downward imposed load on the home is also known as the snow load. Minimum uniformly distributed live loads. 1603 1 2 roof live load. 1603 1 1 floor live load.

0 9d 1 0e effect or 0 9 when resisting the load when permanent. 3 20 residential structural design guide. The ground snow load p shall be indicated. Or s or r l or 0 5w dead load d in 1 through 5 and 7.

The roof live load used in the design shall be indicated for roof areas section 1607 12. 1603 1 3 roof snow load data. For a larger map with greater detail refer to asce 7 98. A clay tiled roof may have a dead load.

In areas of the state outside of certified local government jurisdictions the design snow load shall be based on the ground snow loads developed in snow loads for structural design in montana authored by f f. 0 9d 1 0w a load factor of 1 6 when adding to load 7. The minimum design roof snow load. The north zone design live load equates to 40 pounds per square foot the middle zone equates to 30 pounds per square foot and the south zone equates to 20 pounds per square foot.

1 2d 1 0e l 0 2s when h loads are present they shall have 6. The uniformly distributed concentrated and impact floor live loads used in the design and where they are applied shall be indicated. Roof connection details roof live load engineered framing specs details for fired rated structural elements flood hazard requirements base flood elevation certification flood proofing damp proofing. The dead load of a typical asphalt shingled wood framed roof is about 15 pounds per square foot.

Schilke civil agricultural engineering montana state university august 1989. 1603 1 2 roof live load. Also whether live load reduction has been applied. 1 2d 1 0w l 0 5 l r or s or r 5.

In areas where the ground snow load p exceeds 10 pounds per square foot psf 0 479 kn m2. In areas where the ground snow load is less than 15 psf the minimum roof live load refer to section 3 4 is usually the controlling rgavity load in roof design.