Flat roofing costs in Fulbourn vary widely depending on what the roof needs, what material is used and what the roofer finds when the existing covering comes off.
A flat roof over a small garage and a flat roof over a two-storey extension can both be described as "a flat roof job", but they can differ in cost by a factor of three or more. Size is the obvious driver, but material choice, deck condition, drainage detail, flashing work and access all move the price significantly. This page sets out the main cost factors so you have a realistic basis for budgeting and can make sense of any quotes you receive.
Flat roofing is usually priced per square metre, with the total price then adjusted for the specifics of the job. As a rough guide, a straightforward replacement of a domestic flat roof in this part of the country typically falls in the following ranges:
These are typical current UK figures for a full replacement including stripping, deck inspection, new membrane, flashings and drainage. They are not fixed and will move depending on everything described below.
The two main systems used on domestic flat roofs are torch-on reinforced felt and EPDM rubber. On most jobs, torch-on felt is slightly cheaper on materials, while EPDM carries a modest premium. The gap is rarely as large as homeowners expect - on a single garage, it might be £150 to £300 difference in material cost alone.
The longer expected lifespan of EPDM means the cost per year over the life of the roof is often comparable or lower, even if the upfront price is a little higher. When comparing quotes, check that both quotes specify the same system and the same number of felt layers, if felt is the chosen material. A two-layer torch-on system is not the same as a three-layer system, and the price difference is real.
The single largest variable in any flat roof replacement is what the roofer finds when the old covering comes off. If the plywood or chipboard decking beneath is dry and solid, the job proceeds as quoted. If sections are wet, soft or rotten, they need cutting out and replacing before the new membrane goes down.
Replacing a full sheet of 18mm plywood on a garage roof typically adds £80 to £150 per sheet to the job, including labour and materials. On a roof that has been leaking for years, several sheets may need replacing. On some roofs, the problem goes deeper: wet insulation in an older warm roof build-up, or even rotten joists below the deck, can turn a straightforward replacement into a more substantial piece of structural work.
A roofer who inspects the deck before quoting, rather than after stripping, should be able to give you a view on likely deck condition from probing and looking at the ceiling below. But no quote for a full strip job can guarantee the deck cost until the old felt is off. Any roofer who quotes a fixed all-in price without seeing the deck bare is either guessing or pricing in contingency - ask them to explain how deck replacement is handled in their quote.
A flat roof should drain freely. If the existing roof ponds water, the fall needs correcting when the new roof is laid. This is done with tapered insulation boards or tapered timber firring strips beneath the deck. Fall correction on a standard garage adds roughly £300 to £700 to the job depending on how much correction is needed and how it is achieved. Skipping this step on a roof that already ponds will produce the same problem under the new membrane.
Every junction between the flat roof membrane and a vertical surface needs a flashing. On a typical extension roof abutting the house wall, there is at least one lead or aluminium abutment flashing. If existing flashings are sound, they may be reused after dressing back into position. If they are cracked, corroded or poorly fitted, replacing them is the right approach.
Lead flashing is priced by weight and length. A typical abutment flashing on a small extension might add £150 to £400 to the job. Rooflights, pipes through the roof, and parapet flashings add further cost. Ask your roofer to specify what flashing work is included in the quote and what will be charged as an extra if the existing flashings prove unusable.
Most garage and single-storey extension roofs can be worked from ladders or a small step platform. Where the roof is at first-floor height or above, or where there are adjacent glazed structures, full scaffold may be required for safe working. Scaffold on a domestic flat roof job adds roughly £400 to £900 depending on the configuration needed.
Access for waste removal can also affect cost. A garage with wide gated access makes removal straightforward. A roof over a rear extension with only a narrow side passage means materials and stripped waste need to be carried through the house or garden, which adds time and therefore cost.
Not every flat roof needs a full replacement. A small isolated split or a failed flashing on an otherwise sound roof can often be repaired at much lower cost, typically £150 to £500 for most simple repairs. The question is whether the surrounding membrane is genuinely sound or deteriorating more broadly. Repeated small repairs on an old felt roof cost more over three or four years than a single replacement, so it is worth getting an honest assessment of the whole roof rather than just the area that is currently leaking.
An overlay - laying a new membrane directly over the existing covering without stripping - sits between a repair and a full replacement in cost. It works only if the deck beneath is confirmed to be dry and solid. A typical overlay on a standard garage runs from around £800 to £1,800 depending on size and system used.
To get quotes you can actually compare, make sure each roofer inspects the roof at roof level, specifies the material system in writing, and states clearly how deck replacement and flashing work are priced. Quotes that do not address these points are not like-for-like, whatever the headline price says.
Newmarket Roofers installs and repairs flat roofs on extensions, garages and outbuildings in Fulbourn and across the surrounding area, including Newmarket, Cambridge and nearby villages. Call us to arrange a roof-level inspection and a detailed assessment of what your flat roof actually needs.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
