Roof Surface Preparation in 7 Steps

Preparing and cleaning the roof surface prior to insulation is crucial.

Do you know all the steps to roof surface preparation?

  1. EPDM roof membrane will adhere to certain isocyanurate insulation boards compatible with our adhesives.

However, solvent-based adhesive will melt the polystyrene and water based adhesive will not adhere to polystyrene.

  1. EPDM roof membrane adheres to plywood, OSB (Oriented Strand Board) and 13mm high-density wood fibreboard and concrete.

Polystyrene insulation should not adhere directly to EPDM rubber membrane. If polystyrene insulation is used, cover insulation with 13mm high-density wood fibreboard. Butt all insulation boards together, staggering all of the joints. Any spaces larger than 6.5mm of 25.4mm must be filled to provide a uniform, smooth surface.

  1. Screws and deck plates should be applied at the minimum rate of 8per 4ft x 8ft sheet of insulation, and 5 per 4ft x 4ft sheet or as required by the insulation manufacturer.

When installing insulation around the perimeter, the fastening pattern is 1 screw and 1 deck plate every 0.61mtrs (that is 16 per 1.22  x  2.44mtrs). Examples of fastening patterns are shown in the photo.

NOTE: Extra fasteners should be installed around protrusions such as pipes, chimneys, skylights and irregularities in the roof deck.
  1. Do not install more insulation than can be covered with EPDM membrane by the end of the day.
  2. Reroofing over a wet substrate is not good roofing practice. All wet material should be removed and replaced.

Therefore, the roof surface must be dry as moisture will cause poor membrane adhesion and blistering.

6. The roof surface should be swept to remove dirt, dust and other loose particles.

7. Good roofing practice dictates that the roof surface must have positive drainage of at least 3mm in 30.48cms.

If you have any queries, please get in touch with our friendly team. Call us if you are unsure about the materials you need for your roof on 01392927729 or email You can also check out our Roof Calculator that estimates all the materials you will need for your rubber roofing project.