Cambridge Roofers installs and repairs flat roofs in St Ives using EPDM rubber and torch-on felt, and we will tell you honestly which system suits your roof and why.
Call any time. Calls are answered day and night and passed straight to our roofers.
If you are planning a flat roof replacement in St Ives - whether on an extension, a garage, or a larger outbuilding - the choice of material matters more than most homeowners realise. Different systems have different lifespans, installation requirements, and suitability for different roof shapes. Getting this decision right at the start means you should not need to think about the roof again for a long time.
Cambridge Roofers covers St Ives and nearby towns including Cambridge, Newmarket, and Ely. We install two main flat roofing systems and we will always explain which one we are recommending and why.
There are several flat roofing membranes on the market, but for residential work two stand out as the most practical and well-proven options: EPDM rubber and torch-on modified bitumen felt. Both can deliver excellent results when correctly specified and installed. They work differently, cost differently, and suit different situations.
EPDM (ethylene propylene diene monomer) is a synthetic rubber membrane supplied in large single sheets. It has been used on commercial buildings for decades and has moved firmly into residential flat roofing over the last fifteen years as its advantages became better understood.
A full EPDM system consists of the rubber membrane itself, a bonding adhesive applied to both the deck and the underside of the sheet, and specialist seam tape and lap adhesive at any joints. There is no heat involved in the installation, which makes it practical in tight spaces and on roofs adjacent to timber or UPVC.
Best suited to: Residential extensions, garage roofs, flat roofs with limited access for a gas torch, roofs with unusual shapes requiring careful cutting and bonding, and situations where longevity and low maintenance are the priority.
Torch-on felt, also called torch-applied or hot-bonded felt, uses layers of reinforced bitumen sheet. A gas torch is used to heat the underside of each layer as it is unrolled, melting it onto the deck or the layer below. Modern torch-on systems use two or three layers, with the top (cap) sheet usually mineralised - covered in granules - which protects against UV and physical damage.
Best suited to: Larger flat roof areas, commercial or semi-commercial outbuildings, roofs where the access and site conditions allow safe use of a torch, and situations where a lower upfront cost is a priority.
If you are trying to decide between the two, here is a straightforward way to think about it.
Neither system is right for every situation. Any roofer who tells you there is only one option without first assessing your specific roof is not giving you complete advice.
The membrane system you choose only performs as well as the deck beneath it allows. Flat roofs typically sit on either a timber deck (plywood or OSB boards on joists) or a concrete/screed base. Before any new membrane is laid, the deck must be assessed for moisture damage, soft spots, and adequate falls.
A common problem is a deck that has absorbed moisture from a slow, long-term leak under the old membrane. Laying new EPDM or felt over a soft or rotten deck will not fix the underlying issue and will shorten the life of the new membrane. If sections of decking need replacing, that cost should be identified at survey stage - not discovered halfway through the job.
The fall across the deck also matters. A flat roof is not truly flat - it must have a minimum fall of 1:80 (roughly 12mm per metre) to drain reliably. If the existing falls are inadequate, tapered insulation boards can correct this without rebuilding the deck, though they add cost.
Older flat roofs are often cold roofs, where insulation sits between the joists below the deck. This arrangement risks condensation on the cold deck above. A warm roof puts insulation above the deck and below the membrane, eliminating the condensation risk and improving thermal performance significantly.
When replacing an old flat roof it is worth considering whether converting to a warm roof specification is practical. It adds cost and slightly raises the roof height, but the thermal and longevity benefits are real. We will advise on this at survey stage.
EPDM installations for residential properties in this part of Cambridgeshire typically cost £75-£120 per square metre fully installed, depending on deck condition, access, and the complexity of the layout. Torch-on felt usually comes in at £60-£100 per square metre. A standard garage roof (around 15-20 square metres) typically costs £1,300-£2,400. An extension roof of 30-40 square metres is more commonly £2,600-£4,800, depending on specification.
These figures assume decent access and a deck that does not need wholesale replacement. If decking is rotten, add £30-£60 per square metre for deck replacement. Scaffolding, where needed, adds a further fixed cost.
If you want an honest assessment of your flat roof - what system suits it, what condition the deck is in, and what the job will realistically cost - call Cambridge Roofers to arrange a survey. We cover St Ives and the wider area including Cambridge, Newmarket, Ely, and Royston. We will give you a clear recommendation before you commit to anything.
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Call any time. Calls are answered day and night and passed straight to our roofers.
