When your commercial roof starts leaking or shows signs of wear, it’s tempting to grab a ladder and try to fix it yourself. But when it comes to flat roofing systems like TPO, EPDM, or modified bitumen, not all quick fixes are created equal.
In fact, some of the most commonly used patch products—like Flex Seal, silicone caulk, or roofing tar—can actually do more harm than good.
If you manage a facility or commercial building, here’s what not to use, what works better, and when it’s time to call in the pros.
Products That Often Cause More Problems Than They Solve
These materials might be fine for a quick fix at home—but they don’t belong on a commercial roof:
Flex Seal & Spray-On Coatings
These consumer-grade products might stop a drip temporarily, but they don’t adhere properly to most single-ply membranes. Worse, they trap moisture underneath and are nearly impossible to remove cleanly when real repairs need to be made.Silicone Caulk or Sealant
Silicone might seem like a good waterproofing option, but it doesn’t flex well with temperature changes—and nothing sticks to it later. That means any future repair will require full removal of the area, often making the problem worse and more expensive.Roofing Tar
Tar is messy, hardens over time, and damages the membrane it’s applied to. It’s not compatible with modern roofing materials and can void your warranty. We’ve seen tar cause more damage than the original leak.
What Does Work for Temporary Repairs
If you’re in an emergency situation and need a quick stopgap until help arrives, here are a few better options:
Heavy-Duty Plastic Sheeting or TPO Patch Material
Plastic sheeting weighted with Quickrete or sandbags can help divert water and protect vulnerable areas. For those trained in membrane roofing, TPO patches can be applied using proper tools—but these require knowledge and experience to do correctly.Moisture-Absorbing Compounds (911)
Roofing professionals sometimes use drying agents like “911 compound” to help manage ponding or minor intrusion temporarily. These aren’t long-term fixes, but they can reduce damage while you wait for service.Ballast for Membrane Uplift
In wind-damaged areas, placing weighted objects like unopened Quickrete bags (never sharp or loose materials) can help hold the membrane down temporarily—but only if it’s safe to access the roof.
Why DIY Patches Often Cost More in the Long Run
What looks like a cheap fix today can cost you thousands later. Many of the materials listed above create adhesion problems, void warranties, or force roofers to cut away more of the original system to get back to a clean surface.
And while we understand that leaks can’t always wait, your best move is often to stabilize the area and get a qualified commercial roofer on-site as soon as possible.
Jewett Roofing: Your First Call for Lasting Repairs
At Jewett Roofing, we’ve seen every kind of DIY disaster—and we’re here to help you avoid them. Our team responds quickly to leaks and damage, using methods and materials that preserve your existing system and meet manufacturer standards.
If you’re dealing with a roof issue and not sure what to do next, skip the hardware store and give us a call.
Serving the Greater St. Louis and Greenville regions, we specialize in commercial roof repairs that last—not patches that fail.
Contact Jewett Roofing today to schedule a service call or inspection.
