If you need a flat roof installed or repaired in Fakenham, the contractor you choose matters as much as the material they use.
A flat roof is not truly flat - it is laid to a slight fall, typically 1:80 or better, so rainwater drains to a outlet rather than sitting on the surface. On extensions, garages and outbuildings, that fall is built into the roof deck before any waterproof membrane goes on. Get the fall wrong and you get ponding water, which accelerates wear on any membrane system and eventually finds its way through.
The two systems most commonly used on domestic properties today are EPDM rubber and reinforced felt. EPDM is a single-ply rubber membrane bonded or ballasted to the deck. It handles movement well, which matters on timber-framed extensions that expand and contract through the seasons. Reinforced felt - usually laid in three layers with torch-on application - is more traditional but performs reliably when installed correctly with the right specification for the roof size and use.
This is the part most homeowners skip, and it is where problems start. A flat roof that fails within a few years almost always fails because of poor installation rather than poor materials. The material itself is rarely the weak link.
Here is what to look for and ask before you agree to anything.
A contractor should be able to name the system and explain why it suits your roof. "Felt" is not a sufficient answer - ask whether it is a torch-on three-layer system or a cold-applied system, and what the top layer specification is. For EPDM, ask whether it is bonded or mechanically fixed, and what thickness of membrane they are using. A 1.2mm EPDM membrane and a 1.5mm membrane are different products with different service lives.
If a contractor cannot or will not answer these questions clearly, that tells you something important about how they work.
A new membrane on a failing deck is money wasted. Before any waterproofing goes on, the deck - usually OSB, marine ply or existing timber boards - needs to be sound, dry and properly fixed. Ask the contractor what they will do if they find soft or rotten timber once the old covering is stripped. Will they replace it and at what cost? You want this agreed in advance, not presented as a surprise extra on the final invoice.
Adequate falls also need to be built into the deck. Ask how the fall will be achieved - with tapered insulation, with firring pieces cut into the joists, or whether the existing structure already has sufficient slope. This is not a pedantic question; it is the difference between a roof that drains and one that ponds.
Outlets block with leaves and debris, especially where trees are nearby. Ask where the water will drain to, how many outlets the roof will have, and whether the outlets will be fitted with leaf guards. On larger flat roofs, a single central outlet is often insufficient. Two outlets provide redundancy if one blocks.
A price written on the back of a business card is not a quotation. A proper quotation should list the membrane system and specification, the deck work included, the number of layers or membrane thickness, how flashings will be dressed at upstands and walls, and what happens to the old material (disposal is a cost some contractors quietly omit). If a quotation does not cover these points, ask for a revised version before you sign anything.
Compare quotations on a like-for-like basis. A cheaper price that uses a lighter membrane or skips the deck inspection is not a saving.
Most flat roof leaks do not come through the middle of the membrane - they come from the edges. Where the membrane meets a wall, a parapet, a skylight kerb or a soil pipe, the junction must be properly dressed and sealed. Ask the contractor how they detail upstands and whether lead, code 4 or code 5, or aluminium trim will be used at the perimeters. Poor edge detailing is the single most common cause of flat roof failure after ponding.
For a standard domestic flat roof on a single-storey extension or garage in the Fakenham area, EPDM rubber installation typically costs in the region of £70 to £120 per square metre depending on deck condition, access and specification. Torch-on felt is generally at the lower end of that range, though a quality three-layer system on a large roof can sit at a similar level. These figures assume the existing deck is sound - deck replacement adds to the cost and should be priced separately.
Be cautious of prices significantly below this range. Cutting corners on flat roofing is easy to do and the results often do not show for a year or two, by which time the contractor is long gone.
Extensions account for a large proportion of flat roof work. A poorly detailed flat roof on a rear extension can cause damp to the interior ceiling, damage to the wall where the roof meets the house, and in severe cases penetration into the structure of the main building. The junction between the flat roof and the house wall - the abutment - is a critical detail that should use correct stepped or cover flashings, not just a bead of mastic.
Garages present slightly different challenges. They are often accessed from above for storage and the deck needs to be robust enough to take occasional foot traffic without flexing. Mention this to your contractor so the deck thickness can be specified accordingly.
Dereham Roofers install and repair flat roofs for homeowners in Fakenham and the villages nearby. Call us to arrange a roof survey and we will give you a clear, written quotation covering exactly what the job involves.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
