Replacing an old rubber roof with IB PVC roofing membrane in Lowell, MA.
In the beginning of Dec. 09 we installed a new IB PVC roof in Lowell, MA. This roof replaced an old EPDM rubber roof, which was installed by a hack roofing contractor about two years ago. The roof was failing miserably, due to two factors: poor roofing system design on the part of EPDM, and a horrible installation job by the contractor. I suspect that this contractor had almost zero knowledge about flat roofing and rubber installation. Before I go into the IB roof installation, I want to talk a bit about the two factors mentioned above that contributed to the roof failure.
Rubber roof failure due to EPDM flaws and limitations and faulty installation by a roofing contractor
The roof actually consisted of two sections not connected to each other. One smaller roof in the front of this historic home was about 100 sq. ft. in total, but its shape made using a rubber roof not feasible due to limitations / flaws of rubber roof system design. Another roof section was just over 300 sq. ft. and covered an enclosed porch in the rear of the house. This section had a low slope (about 2 in 12 pitch) and a hip roof design. The failure of both front and rear roof sections was the result of bad installation by the roofing contractor, EPDM membrane’s shrinkage, as well as seam adhesive failure.
When EPDM rubber roofing membrane is installed on a roof connected to a wall of a building, the membrane must be laid down with a flap going up the wall – in essence, the wall flashing and the roof covering must be done with one piece of material to eliminate leaks in the the roof to wall connection. In the case of EPDM, the field sheet of roofing membrane is only held down by glue (which happens to break down after 5-7 years). While in some cases this work out fine, very often the rubber shrinks and pulls away from the wall-to-roof connection point. This results in either the detachment of wall flashing, membrane pulling away from the corner of roof to wall connection, or in some rare cases, when the wall flashing is securely attached to the wall, the shrinking rubber roof may pull the wall with it – for example it can pull a brick parapet wall. Continue reading