Roof Poding Deflection Check

If the beam is stiff enough then ponding can be minimized.

Roof poding deflection check.

An inspector will know how much ponding is acceptable on a flat roof. The more water on the roof the more deflection you get which means that even more water can be retained which leads to more deflection etc. Ponding is a progressive event. Asce 7 10 2015 ibc attributes ponding water to the deflection of relative flat roofs and identifies a susceptible bay for ponding as a roof slope less than 1 4 in 12.

The level roof surface is utilized for air handling units gas vents skylights and other mechanical equipment. Without sufficient stiffness deflection of the roof may cause successive ponding and deflection until the accumulated weight could conceivably cause failure. We moved into the house march 2013. A flat roof for commercial businesses make a lot of sense for a host of reasons.

Hvac units without condensate drain lines could be the culprit. A flat roof serves as a superstructure from which to attach joists and suspend piping hvac ductwork and lighting systems from. Pierce cautions that before roof repairs are hastily made the source of the ponding water should be investigated. Bring in a roofing contractor to perform an inspection once or twice a year to ensure that the membrane is holding up and not worn or damaged in areas.

Asce 7 10 further clarifies roof surfaces with a slope of at least 1 4 inch per foot 1 19º towards points of free drainage need not be considered a susceptible bay. This was noticed for the first time a couple of months after the singles were installed. 5 15 ponding on roofs. My tennessee home was started in may 2012 and the roof was put on in late june.

When there is the possibility of water ponding which may cause excessive loads and additional progressive deflection each component of the roof system including decking purlins beams girders or other principal structural supports should be designed accordingly. Always inspect thoroughly before making a repair. The shingles or sheathing on the homes roof is lifting deflecting causing ripples in the roof. The aisc specification provides formulas by which the stiffness of a roof system may be checked.

Structural failure due to long term effects of ponding water. Check drains to make sure they are free of dirt silt and debris. In roof systems that are essentially flat provisions must be made to support ponding water. The builder was made aware of this issue and had the roofer who framed the house and installed.