Applying HERTALAN® Ks205 Adhesive

With EPDM membranes, the advantages of using them for your roofing and waterproofing are clear, although its advantages outweigh its limitations, the material does have some limitations.

However, many of the common problems that are encountered with EPDM roofs are due to incorrect or improper installation. This is why a trained roofer is essential to any roof installation.

Common EPDM Roofing Problems

Here we look at some common EPDM roofing problems, and how they can be resolved. Once again, you should enlist the help of professional roofers who are trained in installing EPDM to do this, otherwise, you may find yourself worse off than before!

Leaking EPDM Roof Repair

Leaks in EPDM roofs can happen for several reasons, including:

  • punctures in, or damage to, the membrane
  • shrinkage
  • incorrectly installed or improper flashing
  • wrinkles extending into roof seams

The best way to deal with roof leaks is through prevention, rather than cure, as usually, once you’ve noticed a leak, the chances are it’s already done some damage (e.g. if you see patches of moisture appearing on walls or ceilings or notice drips coming through). This is where regular roof inspections and clearing debris away from the roof come in.

Remember that the source of the leak may not be directly above where the damp patch has come through. Water can run in any number of directions, so it’s important to thoroughly inspect the roof space.

When you’ve found the source of the leak, it’s important to determine the full scope of the problem, as if moisture has already got through your EPDM membrane, and it gets trapped, it can cause bubbling and blistering as well as potentially lead to rot. So, it’s more than just fixing the original leak!

Fixes may include re-laying the entire roof, or part of the membrane, applying a patch or re-installing the flashing. It will depend on the issue at hand. If you think you might have a leak, consult a trained roofer to determine the best course of action for your EPDM roof.

Water splashing on EPDM

Repairing Punctures in or Damage to the EPDM Membrane

Even though EPDM is incredibly durable and hard wearing, it can still suffer from punctures, caused by weather damage, objects such as tree branches falling onto the roof, animals, or other trades. However, one of the main advantages to EPDM is that it can be very easily repaired using a patch. There are also puncture-resistant single-ply membranes available (such as RESITRIX®).

EPDM Hole Repair

Firstly, it’s important that the area to be repaired is clean and free from debris. Use an EPDM cleaner like G500 to ensure that the patch correctly adheres to the roof surface.

Measure out the patch, ensuring that you leave at least 50mm of membrane outside the damaged area in all directions. Round off any corners (these can be caught by foot traffic, causing the membrane to lift).

Apply the patch according to instructions for the membrane in question, and ensure fully sealed by checking for the bead of bitumen, weld or sealant that appears when the seam is fully bonded.

If in doubt, again, you should always consult the professionals.


EPDM Roof Membrane Shrinkage

While EPDM roofs are easy to install, the installation MUST be carried out by someone who is trained (and experienced) in installing EPDM roofing. Otherwise, it is all to easy to fall victim to problems caused by incorrect installation, such as shrinkage, for example.

Some common reasons for shrinkage are:

  • failure to fully adhere perimeters and angle changes
  • not allowing the EPDM sheeting enough time to relax before installing
  • not allowing for sheet expansion in warmer weather before applying

Left untreated, problems can develop until they’re much bigger than the original issue. They can lead to potential damage to not just the membrane and the roofing seams, but also to the underlying structure of the roof, drainage outlets and flashing.

A skilled EPDM roofing professional will take into account weather conditions when installing the EPDM membrane and allow it to relax/contract as required. In addition, they will not just cut the EPDM membrane to “fit” but will ensure that the roof is fully sealed, taking into account upstands and roofing features, and leaving sufficient overlap between the membranes to discourage further breaches (approx. 50-80mm).

Unfortunately, it’s likely that if your EPDM roof has been incorrectly installed, and has led to shrinkage, to the extent where you are seeing some of these problems, the only solution is to have it correctly installed by a trained professional roofer.

EPDM Roofing Issues – Poor Installation

Proper preparation is key for EPDM installation.

If the roofing area is not properly cleaned, dried and prepared prior to installation, then this too can create problems further down the line.

Our EPDM systems such as HERTALAN® and RESITRIX® can be installed on most substrates, however you should always check first that the substrate you are using meets the installation requirements, and install a protective barrier if needed.

If the surface is damp in any way, there is the possibility that the membrane will not adhere to it. This can cause air and moisture to be trapped underneath, which can create a “bubbling” effect.

You may see some “waviness” or unevenness on your roof, this is usually found on older roofs where there is residual moisture, on decking where there is natural moisture and on insulation where you can frequently see movement and shrinkage. Due to EPDM’s extreme flexibility, the function of the membrane is not affected, so these changes are merely cosmetic.

Cleaning Mould and Mildew on EPDM Roofing

As roofs are exposed to a whole host of weather conditions and don’t always have time to dry out properly in between bouts of bad weather, mould and mildew can be a potential problem. While there are no components of EPDM rubber roofing that promote the growth of mould or mildew, it is still a risk for this reason.

Mould or mildew won’t harm your EPDM membrane structurally, however it is not pretty to look at, and can be tricky to get rid of completely once it’s appeared. As such, as with many of the other problems listed here, prevention is better than cure,

However if you do spot mould or mildew on your EPDM rubber roof, all is not lost! It can be cleaned using a non-abrasive cleaner and a soft-medium brush.  Vinegar can also be used to clean mould from your EPDM roof. Apply with a sponge, leave to sit for a few minutes and then sponge away. You may need to reapply to get rid of particularly stubborn patches.

Fixing Bubbles and Blisters in an EPDM Roof

One problem you might come across is bubbles or blistering in your EPDM roof. This can occur for two main reasons:

Vapour from bonding adhesive

Bonding adhesives are used to attach EPDM membranes to upstands and around the roof perimeter. When these are solvent-based, if they are not allowed to become touch dry before the membrane is applied, bubbles of gas can form, caused by the trapped vapour from the adhesive.

As EPDM is partially breathable, these bubbles are not a huge problem long-term, and will gradually settle down over time. However, in severe cases, it could mean that the membrane has not bonded correctly, and the membrane may need to be peeled back and re-applied.

Expanding or trapped air within the roof structure

If there is water trapped within the roofing structure, or the timber isn’t completely dry when the membrane is applied, this can also cause bubbles and blistering to form. This happens when the roof heats up, the water evaporates, and the vapour has nowhere to go.

Bubbles and blisters won’t necessarily cause the EPDM membrane to fail, however they can be unsightly. Unless the bubble is over a seam, is in a high-traffic area or you can see that the EPDM membrane on or around the blister is damaged or degraded, it might be better to leave it alone. If one or more of those applies, speak to a roofing contractor.

Carlisle Academy training

EPDM Roofing Training

Many of the problems outlined above are simply down to poor installation or workmanship. However, with specialist training, roofers can learn all the skills and techniques they need to fit EPDM roofs that will last for 50 years or more.

If you’re an architect, home or business owner, or contractor looking for a roofer, make sure you do your research and find one who is trained and experienced in installing EPDM rubber roofing. If you are a roofer, and you would like to learn more about EPDM roofing, our CARLISLE® Academy offers industry-leading training into our various EPDM roofing membranes and their applications.