At Roofing Kits Direct, we understand how worrying it can be to spot bubbles or blisters forming on your brand-new rubber roofing. You’ve just invested in a flat roof that should last decades—so what’s going on? The good news is that in most cases, these issues are easy to explain and can be resolved with the right knowledge and care.
In this guide, we’ll explore why rubber roofing blisters happen, what they mean for the long-term performance of your roof, and what you can do to prevent or fix them.
What Are Blisters in Rubber Roofing?
Blisters or bubbles are raised sections in the rubber roofing membrane, typically caused by trapped air or moisture beneath the surface. They can vary in size and usually appear soft or spongy to the touch. Though they might look concerning, not all blisters indicate serious problems—especially if caught early and monitored.
Why Does Blistering Happen in Rubber Roofing?
1. Moisture During Installation
One of the most common causes of rubber roofing blisters is moisture trapped between the substrate (such as OSB or insulation) and the EPDM membrane. If the deck wasn’t completely dry before installation, this trapped moisture can turn into vapour when heated by the sun. The vapour has nowhere to go, and so a blister forms.
2. Incorrect Adhesive Application
Rubber roofing requires careful use of adhesive, both water-based and contact varieties. If the adhesive isn’t applied evenly, is too wet or dry during application, or if the two surfaces aren’t given enough time to become tacky before bonding, the membrane may not adhere properly. The result? Air pockets that turn into bubbles.
3. Surface Contamination
If the roof deck was dusty, oily, or dirty during installation, the rubber roofing membrane may not bond correctly. A clean, dry surface is crucial to achieve long-term adhesion and prevent blistering.
4. Temperature Extremes
Installing rubber roofing in very hot or cold conditions without proper expansion allowances can stress the material. As the rubber expands or contracts with the weather, weak points can blister under pressure.
Are Rubber Roofing Blisters a Serious Problem?
Blisters in rubber roofing aren’t always a sign of structural failure. If the membrane isn’t torn, punctured, or leaking, the blister is likely a cosmetic issue. That said, some blisters can grow or stretch the membrane, increasing the risk of cracks, UV damage, or seam failures over time.
It’s important to monitor any blisters you notice, especially on newer installations. A quick response can prevent minor issues from becoming major repairs.
What Should You Do If You Spot a Blister?
Stay Calm – Blisters in rubber roofing are common and often not urgent.
Mark the Area – Use chalk to outline the blister and monitor any changes over time.
Look for Leaks – Check the interior ceiling for signs of moisture ingress.
How to Prevent Rubber Roofing Blisters
Prevention starts with proper installation, and we make it easy. At Roofing Kits Direct, we supply complete rubber roofing kits with premium materials and easy-to-follow instructions. To reduce the risk of blistering:
Only install rubber roofing on dry, clean, dust-free surfaces.
Use the correct adhesives for each part of the roof.
Avoid installing during wet or extreme weather conditions.
Allow proper curing and bonding time.
Hire trained installers for larger or more complex projects.
Our Final Thoughts
If you’re asking yourself, “Why are there bubbles or blisters on my new rubber roofing?”, you’re not alone. These issues are relatively common, especially if the roof was installed in poor conditions or in a rush. But they can usually be managed, monitored, or repaired before they cause serious problems.
For best results, always choose high-quality materials and guidance—something we proudly provide here at Roofing Kits Direct.
Need help with your rubber roofing? Get in touch with Roofing Kits Direct today for expert advice and complete EPDM roofing kits delivered across the UK.
