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February 3, 2011 -
Today's tip is about roofing details to keep an eye on to help reduce potential problems down the road.
First and foremost are seams. Seams can often be the weakest point in any section of roof, so walk the roof frequently to make sure that seams aren't separating or wrinkling.
Next, penetrations such as vent pipes and drains, should be carefully flashed and checked frequently to ensure that they’re water tight. For single-ply membranes, use a boot or field-formed membrane adhered to a drawband. For mod-bit or asphalt, use pitch pans or concrete rings and check the sealer often to make sure it's not cracked.
When a roof terminates at a wall, curb or other obstruction, make sure vertical flashings and counter-flashings are installed correctly per manufacturer's instructions so that they're more likely to remain watertight. Roof edges are often the first point of failure in an extreme wind situation. Make sure the material used for counter-flashing is compatible with the roofing material. For instance, polyurethane sealants are chemically incompatible with roofing asphalt. The sealant will prematurely harden and crack.
Finally, when a roof terminates at a metal edge, understand that metal will expand and contract at a different rate than the membrane attached. So check these areas frequently for cracks. Make sure to use an adequate number of fasteners to attach the metal edge to reduce the possibility of blow off. If too few fasteners are used, or the gauge of metal is too thin, the metal can easily peel back in a windstorm.