Rain Loading Configuration On A Roof

During its lifetime a building roof is subjected to a number of different structural loads roof dead loads and roof live loads principally snow wind and rain.

Rain loading configuration on a roof.

Depending upon the location one of these will be the controlling roof live load. Until recently floor live load roof live load roof snow load wind load earthquake design data and flood loads were required to be listed on the construction documents. During a roof installation there are several steps to ensure that your home s interior is never exposed. Sloped or not each segment of the roof shall be capable to carry the loading created due to blockage of the primary roof drainage system of that segment plus the load caused by water that rises above the inlet of the secondary drainage system at its design flow rate.

Above the roof surface primary drain. Diameter drains spaced uniformly along the long sides of the building at 40 ft intervals for the secondary drainage system. The architect has decided to use 6 in. It is not the fault of your contractor and while the delays can certainly be frustrating a contractor who attempts to install a new roof in the rain is going to be compromising the overall integrity of the installation.

Determine the design rain load on the roof of a building that is 250 ft wide and 500 ft long. The secondary drains are located 1 5 in. Should your roof installation have to be delayed due to poor weather be patient. Determine the transient load of the roof.

The accumulation of water caused by the deflection of the roof structure is called ponding and as it results in added load it can lead to roof instability. In northern mississippi it may be rain. Note that although rain loads are covered in ibc section 1611 they were not required to be listed on the construction documents. For a building in northern vermont snow is likely the controlling roof live load.

The event that shall be considered is an intense short duration rainfall. The key to managing rain loads in buildings is roof drainage including a primary drainage system and a secondary drainage system which is set at an elevation higher than the primary system to drain any water that builds up after the lower system is blocked or not working. 2014 fbc building 5 th edition 16 structural design 1611 rain loads 1611 1 design rain loads jump to full code chapter each portion of a roof shall be designed to sustain the load of rainwater that will accumulate on it if the primary drainage system for that portion is blocked plus the uniform load caused by water that rises above the inlet of the secondary drainage system at its design flow. This is all of the natural stresses imposed upon a roof such as snow loads rain loads and wind loads.

This is highly regional as weights of snow for example range from 10 to 300 pounds per square foot based on moisture and volume of the snow. While the completed shingles may not be in place during an unpredicted rainstorm there should be a protective layer on your roof that keeps rain from getting in.