EPDM membrane bridging

EPDM membrane bridgingStaying with the topic of EPDM membrane hidden gutter systems I would like to touch on the topic of membrane bridging. This evolving deficiency occurs on almost all rubber gutter systems. It is due primarily to the fact that the gutter itself was merely loose-laid into the trough and not chemically adhered to the wooden substrate with a bonding agent. Through the lifecycle of the rubber, it dries and shrinks and becomes in non-contact with the underlying deck. This shrinking action results in the pulling-away from the wooden deck and a bridging of the membrane.

The bridging primarily affects the desired water flow of the system to the drain. When a membrane bridges, it causes a rise in the level of the rubber and sometimes builds an obstacle that the water cannot bypass to get to the drain. The end result is a gutter that constantly holds water. This is not an extreme issue of concern if the gutter is installed according to today’s accepted practices. Where this becomes an issue is if the initial installer’s workmanship is failing. Standing water plus poor installation details commonly result in an accelerated fascia board and soffit rot problem.
Extreme cases of membrane shrinkage result in water overflow down the fascia boards instead of the intended flow through the drains and downspouts. Membrane shrinkage can also cause poorly sealed seams to tear apart and become water ingress locations.

Resolution of such bridging problems can be brought about by adding additional drains at critical points or cutting out the extreme bridge locations and patching the resulting cut/hole with appropriate and compatible rubber products applied with accepted and proper means.

If you notice standing water, fascia board and/or soffit damage and are concerned about the cause, contact Crucial Roof Services for a free consultation and estimate.