Bridging Issues on EPDM Rubber Roofs
July 12th, 2010
EPDM (rubber) roofs have become a staple in the roofing industry since the early 1980’s. There are millions of square feet of these roofs which are now between 15 & 20 years old and most of the membranes are still in very good condition. What are some of the issues that need to be identified with these roofs? First and most significant is the fact that the perimeter fastening details that were considered industry standards in the late 80’s and early 90’s didn’t work! These details involved adhering a membrane at the change of plane on a roof without adequate securement. Wood nailers have proven incapable of providing adequate securement. The result of this problem is that many of these roofs now exhibit “bridging” at the change of plane with curb and wall flashings. Bridging can be observed when the membrane pulls away from the wall and takes a short cut to the substrate below. Bridging is most significant in ballasted EPDM roofs and occurs because the EPDM has a natural 2% shrinkage factor. If the flashings are properly fastened the natural elongation and elasticity of the membrane absorbs the movement. Bridging of ballasted EPDM What can you do if your roof fits this description? If the underlayment is dry these roofs can be repaired in a manner that promotes continued performance life of the roofing system. With proper attention to the seams and other flashings EPDM roofs installed over dry, solid insulation can perform for an extended period of time. The key word here is dry insulation. Once significant moisture enters the roofing system the useful service life of these roofs is near the end.
By admin
Posted in: Roof Inspection, Roof Repair Project, Roof Replacement Project
This entry was posted on Monday, July 12th, 2010 at 9:08 pm and is filed under Roof Inspection, Roof Repair Project, Roof Replacement Project. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.
