How To Lay An EPDM Rubber Roofing Membrane

Laying an EPDM rubber roofing system, whether that may be a product or membrane is one of the most difficult tasks for homeowners and newly-trained roofers. 

Ethylene Propylene Diene Monomer (M-class) otherwise known as EPDM, is a synthetic rubber with extreme durable properties utilised across a diverse range of applications - with one application including roofing systems. 

Why use EPDM as a roofing system?

EPDM is recommended for roofing systems due to their heat and weather-resistant properties. The material consists of two main ingredients that are derived from natural gas and oil which allows it to become an ideal flat roofing material.  

EPDM roofing systems are also designed for flat and low-sloped surfaces, keeping water from slipping through its structure and preventing damages such as leaks throughout your home. This allows EPDM roofing systems to be a top choice for waterproofing a roof structure. 

Photo by Cleyder Duque from Pexels

Ideal for garages, green roofs, flat roofs and dormer roofs, EPDM rubber roofing systems are highly recommended for any home or property! 

There are some complex steps in ensuring an EPDM rubber roofing system is applied correctly and effectively. We have condensed each step below for an easy-to-follow guide for laying an EPDM rubber roofing system. 

List of items you need

Before you start, make sure that you have the following items and equipment ready in hand: 

UK Flat Roofing has most of these tools available in store, with other equipment sets such as EPDM roofing and gutter kits, and classicbond EPDM products available for purchase.

Step 1:  Prepare, install and sweep the membrane.

To prepare your roof deck, ensure that the roof’s surface is cleaned. Start by scrubbing off any oil, grease and rust, while dusting off any excess dirt that may appear on top of the deck. 

Once done, install a drip batten wherever a gutter is present. This allows the roof deck to extend, ensuring all water drips off of the roofing system rather than behind it. Installing a drip trim is also an important part of the process, and should be installed by aligning the curved top edge of the trim with the timber batten. Use nails to ensure that trim is correctly installed. 

After this, chase out the brick mortar joint using an angle grinder to accept wall trim flashing, then roll out the EPDM membrane into position.

Step 2: Apply EPDM

Once the first step has been completed, it’s time to apply the relevant deck adhesive. Using a paint roller, apply a water-based deck adhesive to the exposed roof deck (do this by folding back the membrane!). 

Roll the membrane into position immediately after applying adhesive to ensure proper adhesion. Once done, sweep the membrane to flatten out on the roof deck, and remove trapped air. Now it’s time to roll out the next row of EPDM, following the previous steps above. 

Step 3: Apply primer and ensure all bubbles are gone.

After this, apply the DuoPly Primer using the marked lines as a guide to the bottom sheet, which can be done using a brush. Leave for 10 to 15 minutes to dry. 

Remove film from pre-applied tape and press the top membrane onto the primed area until all film is removed along with the seem. 

Use a seam roller to ensure there are no bubbles along the membrane, and then apply a thin coat of contact adhesive to the roof deck perimeter. Once done, trim all excess material from the walls. 

Step 4: Apply elastoform and primer

Now we apply the elastoform. Firstly, cut elastoform into the appropriate size which can allow it to stand an extra 75mm on the length by 150mm on the width. Before applying the elastoform, we need to ensure the rubber primer is installed.

Apply an even coat of EPDM rubber primer with a paintbrush to an area slightly larger than the elastoform patch. Once applied, ensure the primer is touch dry, then install in elastoform tape. Apply light pressure using a penny roller to ensure elastoform bonds to all surfaces.

Step 5: Ensure wall trims and pig’s ears are applied correctly.

Now it’s time to install wall trims! Install wall trims along the sides to ensure they chase out mortar joint. Install trims by drilling into the wall with a 7mm masonry drill. Ensure rawlplugs and fasteners along the wall trims to ensure security. 

Once done, analyse your roof deck and see if you can fold the membrane without cutting or detailing an external roof corner before you installed the edge trims.

To form a pig’s ear, pinch the rubber membranes together to form a “pig’s ear”. Fold pig’s ear on side of roof, and apply using staples. Once this has been applied, ensure you seal the pig’s ear by fitting the trim corner to apply pressure. Use nails and batten trim corner in position. 

Step 6: Finish off roofing deck by trimming excessive membrane and fitting joining clip!

Cut the kerb edge trim to length and apply pressure to the top of the trim. After this, snap the joint clips into position. Using polypins, install jointing clips where necessary and trim excess rubber membrane using a knife or scissors. 

You now have a completed rubber roofing system!