EPDM roofing is a modern, reliable solution for creating a durable and watertight flat roofing system.
The following step-by-step guide outlines the essential stages - from meticulous surface preparation and adhesive application to expert finishing details - ensuring your EPDM roof is robust, long-lasting, and weatherproof, whether you’re working on a home extension, garage, or commercial project.
1. Roof Surface Preparation
Tools Required:
- Cordless drill with countersink
- Countersunk screws
- Belt sander
- Leaf blower
Steps:
- Countersink all screw holes into the OSB roof deck to ensure a flat surface.
- Use a cordless drill to fix all screws, making sure screw heads are flush.
- Sand all joints of the roof deck to smooth any protrusions.
- Remove all dust and debris with a leaf blower.
Tip: The prepared surface should be clean, dry, and free from contaminants (e.g., oil, dust, bitumen).
2. Mark Perimeter for Adhesive Application
Tools Required:
- Combination square
- Marker pen
- Heat gun
- Scribe
Materials:
- Contact Bonding Adhesive
Steps:
- Set the combination square to 150mm.
- Mark a 150mm strip around the roof perimeter with the marker pen—this indicates the area for contact bonding adhesive.
- Unfold and position the EPDM membrane. If there are creases, use a heat gun to remove them.
- Fold the membrane back and use a scribe to mark the membrane at 150mm along the perimeter, matching the marked roof strip.
3. Bonding the Membrane to the Roof
Tools Required:
- Medium pile paint roller and pole
- Broom
- Safety goggles
- Stirrer
- Mini paint roller
- Craft knife
Materials:
Steps:
- Fold back part of the membrane to a manageable size.
- Shake and pour large even drops of water-based adhesive onto both the roof deck and the underside of the membrane (within the marked area).
- Use the paint roller to evenly coat both surfaces.
- Lay the adhesive-coated section of membrane onto the roof deck.
- Use a broom to smooth the membrane and push out air bubbles.
- Repeat for each section until the entire membrane is laid.
- Place a protective offcut and a tin on the installed surface, stir contact adhesive, then use a mini roller to coat the 150mm perimeter strip on both roof and membrane undersides.
- Check adhesive is touch-dry before applying membrane—this prevents bubbles.
- Smooth the perimeter membrane into place by hand.
- For wall upstands: apply contact adhesive up to 150mm on the wall and corresponding membrane. Ensure adhesive is touch-dry, press membrane into the angle change, and trim excess.
4. Weathering Wall Terminations
Tools Required:
- Craft knife
- Tape measure
- Scribe
- Scissors
- Paint brush
- Silicone roller
- Penny roller
- Sealant gun
Materials:
- 9-inch uncured flashing tape
- EPDM primer
- Lap edge sealant
Steps:
- Cut membrane 45° at the wall termination.
- Measure, cut, and round off a 150mm patch of flashing tape.
- Scribe a template on the membrane, apply primer 5–10mm beyond template, allow to dry.
- Remove tape backing and apply patch, using rollers for firm adhesion.
- Apply lap edge sealant around patch edges.
5. Installing Roof Edge Gutter Trim
Tools Required:
- Hammer
- Ringshank nails
- Mini paint roller
- PolyTop nails
Materials:
- Gutter trim lengths
- Contact Bonding Adhesive
Steps:
- Position gutter trim back plates slightly below roof deck level, secure with ringshank nails.
- Apply contact adhesive to membrane’s underside and back plates, wait until touch-dry.
- Pull membrane over back plates.
- Remove trim’s protective film, fit front plates, and secure with PolyTop nails and fixing pins.
6. Installing Raised Kerb Trim
Tools Required:
- Fine tooth handsaw or multicutter
- Hammer
- PolyTop nails
Materials:
- Raised kerb trim lengths
Steps:
- Cut raised kerb trim to size, position at roof edges.
- Remove protective film and fold membrane into corners.
- Compress foam strip on trim for watertightness, nail trims with PolyTop nails and fix corner pins.
7. Installing Roof Edge Corners
Tools Required:
- Craft knife
Materials:
- Raised kerb trim corners
- Superglue and activator
Steps:
- Snap out kerb trim side of external corner component.
- Apply superglue to inside edge of component, activator to fitted trim corner.
- Press and hold corner in place until set.
- Trim any excess membrane at the bottom edge of the trim with a craft knife—take care not to damage fascia.
8. Final Checks
Tips:
- Ensure all edges, joints, and trims are securely adhered.
- The membrane should be flat, smooth, and fully bonded.
- Address any unbonded sections, trim excess membrane and apply further sealant if needed.
