Tuesday, April 5, 2011

Roof Penetrations Can Be the Weak Link

Every roof has them, and many of us know the headaches they can cause. We’re talking about roof penetrations (vent pipes, drains, pitch pockets), which are often a roof’s weak link. With single-ply membranes, this means a boot or field-formed membrane that is adhered or welded to the roof membrane with a draw band — a metal collar that fits around the protrusion — and sealant at the top. It’s important to ensure that the draw band is tightly attached but does not cut into the flashing and that the sealant at the top is installed with no voids or unadhered sections. The membrane flashings on single ply roofs at pipes and other penetrations, no matter what the material used, are usually the first items on the roof to deteriorate from age and abuse, so careful attention should be paid to the condition of these flashings.

A modified-bitumen or asphalt roof will often use pitch pockets with pourable sealers. Alternatives are goosenecks and perma-flash. Pitch pockets are the most common, with a weak link occurring when the pourable sealer deteriorates and cracks over time. This is accelerated by any movement in the penetration, causing a separation between the penetration and the sealant. Watching for signs of cracks in the sealant in the pitch pocket and around the penetration. Re-sealing these areas routinely will help keep the roof watertight. Your RAMCON technician can ensure that the sealer is filled to the pitch pocket top to keep the penetration from holding water.

With pitch pockets, there can be additional problems. It’s vital that the sealant applied be appropriate for the roofing system. If the sealer used is asphalt or roofing cement, it will shrink over time, causing cracks within the sealer itself or causing it to pull away from the penetration. This leaves a direct path for water to enter the roof. Regular maintenance of the pitch pans includes crowning the sealer to shed water away from the penetration. RAMCON always utilizes stainless steel pitch pockets on our roofing systems, but many contractors do not. If another contractor used galvanized pitch pockets, checking the pan for rust is essential. Wherever the rusting occurs, there will eventually be a hole.

Metal penetration flashings are dependent upon compression tape and elastomeric sealants to keep the penetration watertight. The sealants should be examined on a regular basis and replaced when they begin to harden and crack. With both the pitch pockets and the metal flashings, the membrane stripping between the flanges of the metal and the roof should be adhered tightly to both the metal and the roof for an adequate seal.

If you have problems on your roof, there is a good chance it is directed from roof penetrations. Trust the professionals at RAMCON to install these correctly and fix any problems the right way.

1 comment:

  1. Thank you for sharing this very nice information. I always want and love reading quality contents.Thanks