1.2mm EPDM Rubber Roofing Membrane – BBA Certified, Cut to Size

The standard-thickness EPDM rubber roofing membrane, cut to your exact size and supplied as one continuous sheet — no seams, no joining on the roof, and nothing rounded up to a full roll. It is bonded cold with adhesive, so there is no torch and no naked flame anywhere in the job. Twenty widths from 0.53m to 15.24m, and any length up to 30.5m.

How the pricing works

Pick a width, then set the quantity to the number of metres of length you need. Every width works out at exactly the same rate per square metre — a 0.53m offcut and a 15.24m sheet cost the same per m². There is no cutting charge, no minimum order and no surcharge for awkward dimensions, and the price you see already includes VAT.

Worked example: a 4.04m wide sheet at 6 metres long is 24.24 m². Multiply that by the per-m² rate and you have the delivered price — that is the whole calculation.

What size should you order?

Measure the roof deck, then add 150mm to each of the four sides so the rubber can dress down over every edge. Take the next width up from the list, and round the length up to whole metres.

Where the roof has an upstand, a kerb or a wall, add more than 150mm on that side — the membrane has to climb it as well as turn the edge. If you are between two widths, always take the larger: surplus trims off in seconds with a knife, but a sheet 50mm short cannot be rescued.

Work out my size and price Handles L-shaped and pitched roofs, skylight voids and every adhesive and trim quantity.

Which thickness do you need?

1.2mm is the right answer for most roofs — extensions, garages, garden rooms, dormers and porches. Step down to 1.0mm for sheds and small outbuildings nobody walks on, or up to 1.5mm for commercial spans and roofs that take foot traffic. Being honest about it: extra thickness buys resistance to damage, not extra waterproofing — how the sheet is bonded and detailed is what keeps water out. The thickness guide goes into the detail.

Specification

What else you will need

Membrane on its own does not make a roof. For a typical fully bonded job you also need:

• Water-based deck adhesive for the field of the roof, and contact adhesive for the perimeter and any upstands — the adhesives guide explains which goes where and how far a tin goes
• Drip trim for the gutter edge and kerb trim elsewhere, with a moulded corner at every turn — see all trims
• Lap sealant for finishing bonded edges
• Seam tape and primer only if the roof is bigger than a single sheet or you are joining to existing membrane
• An EPDM pipe boot for any flue, soil pipe or cable that passes through
• A DIY installation kit if you do not already own a seam roller, scissors and brush

Send us your dimensions and we will list exactly what you need and what it comes to — we would far rather answer a question before you order than process a return afterwards.

Delivery, dispatch and returns

• Free delivery to UK mainland addresses on every order, whatever the size.
• Same-day dispatch on orders placed before 2pm on a working day.
• 1–3 working days on a tracked courier once dispatched.
• Membrane is cut to order, so once it has been cut it cannot be returned. Unopened, uncut stock items can be returned within 30 days.

Frequently asked questions

How is the membrane priced?

By the square metre, at the same rate for every width. Choose your width, set the quantity to the number of metres of length, and the price shown is what you pay — VAT included, delivery free, no cutting charge.

What size should I order?

Your deck size plus 150mm on each of the four sides. Take the next width up from the list and round the length to whole metres. A 3.5m × 5m deck needs roughly 3.8m × 5.3m, so order the 4.04m width at 6 metres.

Do I need to allow extra for upstands or a kerb?

Yes. The 150mm allowance covers turning the edge on a simple roof. If the membrane has to climb an upstand, kerb or wall, add that height on top on that side.

Will there be a join or a seam?

No. Every order is supplied as one continuous sheet at the size you specify, up to 15.24m wide and 30.5m long. There is nothing to tape and no seam that can fail later.

What is the biggest single sheet you can supply?

15.24m wide by 30.5m long. Very few domestic roofs come close, which is why almost every job is seamless.

What thickness do I need?

1.2mm suits most roofs — extensions, garages, garden rooms, dormers. Use 1.0mm for sheds and small outbuildings, and 1.5mm for commercial spans or roofs that get walked on.

Does a thicker membrane make the roof more waterproof?

No, and we would rather say so. All three thicknesses are the same rubber and equally waterproof. Thickness buys resistance to punctures and foot traffic. Leaks come from poor bonding and poor detailing, not from the sheet.

What colour is it?

Slate grey. It weathers to a slightly matt finish and does not fade to a different colour.

What else do I need to buy?

At minimum: water-based deck adhesive for the field and contact adhesive for the perimeter and upstands. Most roofs also want edge trims with corners, and lap sealant to finish the bonded edges. Pipe boots, seam tape and primer are only needed if your roof has penetrations or a join.

Which adhesive goes where?

Water-based deck adhesive bonds the big flat field — it is rollered on and the membrane laid into it wet. Contact adhesive bonds anything vertical or at an edge: it goes on both faces, is left until touch-dry, then grabs instantly. Never swap them.

How much adhesive will I need?

As a rough guide, a 5-litre tin of water-based deck adhesive covers around 20 m² of deck. Our calculator works out exact quantities including the perimeter contact adhesive, or ask us with your dimensions.

Do I need a primer?

Not for bonding to sound timber decking. Primer is for detail work — bonding tape, flashings or patches to the membrane surface.

Can I lay it over my existing felt roof?

Sometimes, but stripping is better. Overlaying only works if the old felt is fully stuck down, flat, dry and free of mineral chippings. Stripping back to the deck lets you find and replace soft boards before you cover them for fifty years.

What can the membrane be bonded to?

Sound timber decking — OSB3, WBP plywood or planed board. Concrete, metal and insulation boards are all possible but need different preparation, so ask us first.

Does the roof need a fall?

A minimum of 1:80 towards the drainage edge is recommended, which is 25mm of drop for every 2m of run. EPDM tolerates standing water, but a roof that drains dries faster, stays cleaner and lasts longer.

Does it cope with ponding water?

Yes. EPDM is unaffected by standing water, unlike felt, which is why it suits older roofs where the falls are less than perfect.

Is it safe to walk on an EPDM roof?

For occasional maintenance in soft-soled shoes, yes. It is not intended as a walking surface for regular traffic — add walkway pads if the roof will be used. Never walk on it wet or frosty; it becomes very slippery.

Can it be laid in cold or wet weather?

The membrane itself is unaffected, but the adhesives are not. You need a dry deck, a dry day and 5°C or above, with no rain forecast until the adhesive has cured.

Which side of the membrane goes up?

Membrane of this type is the same on both sides, so there is no wrong way up. Just keep the face that touches the deck clean and dust free.

How do I join two pieces if my roof is bigger than one sheet?

Overlap the pieces by 75mm, prime both faces of the overlap and join them with seam tape, rolled hard from the centre outwards. Plan the seam across the fall and never through a detail. Our installation guide covers it step by step.

How long does it last, and is it guaranteed?

A life expectancy of up to 50 years, with a manufacturer product guarantee. Felt on the same roof would typically need replacing five or more times over that period.

Is the membrane certified?

Yes — BBA certified under certificate no. 19/5670, and fire-tested to BS 476 and EN 13501. If your building control officer or insurer wants the paperwork, email us and we will send the certificates.

How is it cut — will the edges be straight?

It is cut square from the roll to your stated width and length before it is packed. Small variations of a few millimetres are normal on rubber, which is one more reason for the 150mm allowance.

Can you cut an L-shape or work from a template?

We supply rectangles. For an L-shaped roof, order the smallest rectangle that encloses the whole shape and cut the notch on site — our calculator does that sizing for you and prices the trims for each edge.

Can I return it if I order the wrong size?

Cut-to-size membrane cannot be returned once cut, which is exactly why we would rather check your measurements with you first. Send the dimensions and a photo before you order.

How is it delivered and how long does it take?

Rolled and wrapped on a tracked courier, free to UK mainland addresses. Order before 2pm on a working day and it is dispatched the same day, arriving in 1–3 working days.

Guides that go with this membrane

• How to install EPDM roofing — the full method, start to finish
• Thickness guide — 1.0mm, 1.2mm and 1.5mm compared
• Adhesives and primers guide — coverage rates and flash-off times
• Fitting edge trims
• The full EPDM Learning Centre