Behind The Scenes Of Patching Waterproofing Membrane

Theoretical questions are seldom helpful in the hectic daily work of managing a commercial property. Yet you can hope your facilities crew is asking a rhetorical question if they say, “Can you patch a waterproofing membrane?” That question comes up because, somehow, the waterproofing membrane on your property’s roof has failed. This is a headache you don’t want, often have, and can seldom cure in-house.

Causes of Leaks

A low-slope roof can have leaks in particular areas, most often where the roofing membrane has been deliberately pierced. Other suspect areas are anywhere the underlying insulation has been depressed, either from heavy treads of third-party vendors (HVAC repair workers, for example) or from ponding.

The perimeter of any roof is also a prime spot for leaks. The membrane may have pulled back due to thermal expansion and contraction, so it no longer laps up the vertical parapet side. Unprotected by flashing, the membrane allows water into your roof deck.

The biggest challenge with finding sources of water leaks in a low slope roof: the surface entry point could be feet or yards away from the interior drip-drip-drip. Rely on the expertise of your local commercial roofer to find and stop the leak in your waterproofing membrane. 

When to Patch

“Patch” may not be the perfect word in a question like, “Can you patch waterproofing membrane?” Sure, some waterproof membrane is a sheet product that can be hot- or cold-applied as a patch. Some membrane, though, is applied as a liquid. Liquid Applied Membrane (LAM) can be sprayed even during your business hours thanks to low-odor, controlled application and low noise levels. 

LAM works very well on highly irregular surfaces, steep-pitch roofs, and around roof projections. Because it is a liquid, it is a quick way to patch and repair existing membrane. It can be applied cold, it cures quickly, and it goes on with no penetration of the roof deck, saving time and materials. 

You and your roofer can decide when patching makes sense. S few factors that support this small-scale solution:

  • Limited damage, by square footage or degree of water infiltration
  • When staving off complete roof replacement as a money-saving move
  • When preventing a small leak from worsening while planning a more extensive strategy
  • When maintaining an existing, water-resistant roof 

When to Replace

By partnering with your local roofing contractor, you have an experienced hand able to help you decide when to patch a waterproof membrane and when to replace it. Two major factors will tilt toward replacement:

  1. Age — A membrane with accelerated aging due to weather, climate, neglect or inferior installation may be in desperate need of full replacement, rather than stop-gap patching efforts
  2. Extent of damage — Even a relatively new roof may require replacing if it has sustained damage across significant portions of the surface. This could be from harsh weather, hail, tears in the membrane, or disruption of the surface (installations of new HVAC equipment, for example)

How to Patch Waterproofing Membrane

Existing waterproofing membranes break down into two distinct groups:

  1. Thermosets — Adhesive-bonded materials that “cure,” or set up, such as Chlorosulfonated Polyethylene (CSPE), Ethylene propylene diene terpolymer (EPDM), Epichlorohydrin (ECH), Neoprene (CR), and Polyisobutylene (PIB)
  2. Thermoplastics — Seamed with heat welding (hot air) or solvent welded, this group of membranes includes Polyvinyl Chloride (PVC), Chlorinated Polyethylene (CPE), Thermoplastic Polyolefin (TPO), and Ketone Ethylene Ester (KEE)

When patching, you must join like to like. Attempting to patch waterproofing material that is from the thermoset group with a patch from the thermoplastic group will not work, either in the short term or the long run.

Most building managers cannot instantly recognize the composition of a membrane just by looking at it. For expert advice, turn to your local, dependable commercial roofer. 

Go Pro

An experienced commercial roofer can perform all the due diligence needed to patch the waterproofing membrane correctly. This is not a one-and-done repair. You and your in-house facilities crew may be eager to put a stop to a water leak by slapping some bituminous roof patch from a can on the membrane. Your commercial roofer will choose a different, and better, route:

  • Survey — From a simple visual inspection to use of infrared camera technology to monitor roof temperatures (even below the membrane), an extensive survey can reveal unseen damage, set a baseline for repair and improvements, and guide future repair/replacement decisions
  • Strategize — You and your roofer, working from the survey, can discuss your options, including localized patching, application of LAM, or more extensive tear-off and replacement
  • Succeed — When carefully applied, using the right tools, materials, and equipment, a waterproofing membrane patch can buy you years of useful roof life, which is a great measure of success

The waterproofing membrane does not self-heal. Your fastest solution to stopping leaks in any waterproofing membrane is to act quickly: contact the professionals of PSI Roofing today