EPDM roof calculator: flat roof materials and costs

The calculator works from the roll layout, not just the area, and takes parapets, pipes, roof drains and the substrate into account. It is still a guide: exact quantities depend on the roof design, wind load and details, so before work starts we inspect the roof or check it against the drawings.

No. The calculator shows material costs including VAT. Installation is quoted separately after a roof survey or from the project. Press «Request a price with installation» and your calculation is added to an email.

Add the parapet upstands (up to the top of the parapet), seam overlaps (at least 10 cm) and an edge allowance to the roof length and width. Rolls are laid to keep seams to a minimum, and leftovers are used for parapet strips. The calculator does this automatically and shows the layout of every roll.

An adhered system suits concrete, OSB and PIR boards and gives a smooth, wind-resistant roof. Mechanical fastening is common on steel deck and mineral wool, but the number of fasteners comes from a wind load calculation. For a ballasted system, the roof slope and whether the structure can carry the extra load both matter: we will help you calculate this. If you are not sure, send us a photo or the project.

The material price per m² appears in the calculator as soon as you enter the dimensions: it depends on roof size, parapet length, substrate and the number of details. Smaller roofs cost more per m² because details make up a bigger share. We prepare a full price with installation on request.

Yes, in most cases. The old covering can stay as the substrate if it is dry and firmly bonded: loose areas and blisters are repaired and the surface is cleaned. EPDM must not come into contact with hot bitumen or oils, so before work starts we inspect the old roof and choose a suitable system.

Usually not. If the old covering is dry and well bonded, EPDM goes on top, which saves time and money. It has to come off if there is moisture underneath, the insulation is wet or there are too many layers. We find this out during the survey.

The expected service life of RubberGard EPDM is more than 50 years, and the membrane stays flexible down to −45 °C. To get that life, seams and details must be done right, so we build them to Elevate rules.

For adhered work the surfaces must be dry and free of ice, and contact adhesive is applied only at +5 °C or warmer. We do not glue in the rain. For cold weather there is the self-adhesive RubberGard SA membrane, which can be laid down to −7 °C. We plan the work around the forecast.

It depends on roof size, parapets, the number of details and the weather. Wide EPDM rolls mean fewer seams, so the work goes faster. We give an exact timeframe in the quote after a roof survey.

Yes. You can walk on the roof for maintenance, and walkway pads are laid where people walk often. Under solar panels and terraces a 1.5 mm membrane and an extra protection layer are used, and we check that the structure can carry the load. We plan these details into the calculation.

Each pipe gets a watertight detail: a ready-made EPDM Pipe Flashing (for pipes Ø 25–152 mm) or EPDM tape, with the edge finished in sealant. The calculator adds these materials by the number of pipes.

EPDM is a synthetic rubber: it stays flexible even in frost, and seams are joined with tape, without a flame. Bitumen roofing is usually torched on. PVC membrane seams are welded with hot air. More: EPDM or bitumen felt.

Yes. Water has to run to the roof drains or the edge so that no puddles stand on the roof. If there is no slope or too little, it is built with tapered insulation. We will help you work out the falls and where the drains go.

We state the warranty terms and period in the quote and the contract. They depend on the system, the substrate and the scope of work.