April 13, 2023
Pipe penetrations are one of the most common types of roof penetration in commercial metal roofs. Regarded for their proven record of longevity and value in providing weathertight solutions, a metal roof’s performance can be compromised by improper pipe or flue penetrations to accommodate other building systems. Done poorly, metal roof penetrations can cause leaks, building damage, and unnecessary expenses. When expertly designed and installed, however, pipe and flue penetrations may be successfully integrated into metal roofing systems without compromising performance. Here are five proven and practical guidelines to help avoid problems.
A qualified roofing installer is the best person to cut and install appropriately flashed and booted pipe penetration. If that isn’t possible or practical, then any penetration installed by another contractor should be fully coordinated with the architect/owner’s representative and the roofing contractor. This is the only way to be sure that the integrity of the roofing system is maintained.
Use Only Commercial Materials for Pipe Penetration – To properly seal around the pipe penetration, use only a rubber roof jack made specifically for use with metal roofs. Do not use residential-type roof jacks or those designed for other roof types – they will not last over time. Further, do not use materials that are dissimilar to the standing seam metal roof, such as copper, lead, or galvanized metal roof jacks, which can corrode the metal roof system, or are of inferior quality with a short service life (less than 20 years). Proper commercial roofing products combine an EPDM rubber boot (or silicone for high-heat applications) with a bonded aluminum band to allow a compression seal to be formed at the roof panel.
All planned commercial pipe and flue penetrations should be assessed first to be sure they are not inadvertently creating a potential leak or other problem. Rather, they should be located so they can be properly sealed with no immediate obstructions that would make the seal to the roof unnecessarily difficult or compromise the long-term performance of your pipe or flue penetration.
The metal roof flue and pipe penetration must allow for thermal movement of the roof. Pipes or other penetrations that are rigidly attached to the structure below may not be able to move as the roof expands and contracts. In these cases, the hole in the standing seam roof should be large enough to allow for this movement without the roof panels impinging on the penetration.
If the penetrations are to be included in a manufacturer’s weather tightness warranty, the manufacturer must approve in writing beforehand the materials and methods to be used to install the penetrations. Failure to follow this guideline may result in the penetrations being excluded from the weather-tightness warranty. If everyone involved with the roofing penetrations is aware of and follows these five guidelines, then in the end everyone should be quite happy with the long-term performance of the roof. If not, the potential for roof leaks and other related problems only increases.