EPDM Roofing Calculator

Over what types of structural roof decks can EPDM roofing be installed?

Wondering what EPDM can be laid over? Many roofers and contractors are surprised about how versatile Ethylene Propylene Rubber roofing can be. For example, warm deck flat roofs can be built on top of most modern roof decks like concrete, timber and timber-based sheets. Sometimes, it can even be bonded to lightweight, non-porous surfaces like fibreglass. Still, it works best when adhered to timber decking, particularly roofing grade plywood or OSB sterling board. See all roof types.

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Full list of appropriate decking types

  • Plywood (Roofing-Grade)
  • OSB (Oriented Strand Board) / Sterling Board
  • Concrete (Cast-in-Place or Pre-Cast)
  • Steel Decks
  • Wood Planks
  • Asphalt-Based Roofs (BUR – Built-Up Roofs)
  • Gypsum Decks
  • Lightweight Insulating Concrete
  • Composite or Cementitious Wood Fiber Decks
  • Existing EPDM Roofs (for re-roofing)
  • Fibreglass
  • Tissue-faced insulation boards

Wooden decking (Plywood/OSB)

Rubber roofing membranes connect well to wooden surfaces like plywood or OSB (chipboard or sterling board).

  • Timber decking provides a stable and smooth surface
  • Timber enhances the adhesion of the membrane
  • Ensures a long-lasting, durable and strong bond
  • Used mostly in residential and light commercial roofs

Concrete decks (lightweight)

It’s less common for rubber roofing to be installed on lightweight concrete, but it’s not impossible.

  • The concrete surface should be clean, smooth and free from dust.
  • Primers and specific adhesives should be used to help the membrane adhere better. See range.
  • A concrete deck is more common in commercial roofing applications.

Fibreglass (non-porous substrates)

The answer is yes if you’re wondering if EPR will stick to fibreglass. It’s also suitable for tissue-faced insulation.

  • EPDM is suitable when the non-porous surface is clean, dry and adhesive-ready.
  • To improve thermal efficiency, installers can apply EPDM to tissue-faced boards for flat and low-slope roofs.
  • The biggest consideration is ensuring the adhesive is compatible with the non-porous substrate. Our EPDM primer can be used on non-porous substrates to promote adhesion, as it creates a surface that helps the adhesive bond more securely. See primer.
  • Our Contact Bonding adhesive is also suitable for applications on various surfaces, including GRP. To be used after priming.

Existing rubber roofs

You can even install a new rubber roof membrane on top of old ones if the original membrane is in good condition. Applying a new rubber membrane layer is particularly common in re-roofing or repairs as it’s cost-effective, structurally beneficial, improves performance, enhances insulation and minimises disruption.

  • Before adding a new layer, ensure the underlying rubber roof is clean and free from damage.
  • If the roof needs to be repaired, the repairs should be made before applying the new membrane.
  • Adding additional insulation or a hoverboard between the old and new layers will enhance the thermal performance and provide a smoother surface.