Flat Roofing in Cambridge

What's involved

How we handle flat roofing

Flat roofs are common on single-storey extensions, outbuildings, garages, bay windows and older terraced properties. When they are installed and maintained well, they perform reliably for many years. When they are not, they leak, pond water and cause damage that spreads quickly into the building below. We carry out flat roof replacements, repairs and new installations across Cambridge and the surrounding towns and villages.

Flat Roof Systems We Install

We install two main types of flat roofing membrane: traditional built-up felt and EPDM rubber. The right choice depends on the size and shape of the roof, the condition of the deck beneath, and what will give the best long-term result for that particular building.

Built-up felt - a layered system using two or three courses of bitumen felt, torched or bonded together. It suits straightforward rectangular roofs and is a proven, cost-effective option where the fall is adequate and the deck is sound.
EPDM rubber - a single-ply synthetic rubber membrane that is bonded directly to the deck. It is flexible, handles temperature movement well, and is particularly suited to roofs with awkward shapes, multiple penetrations (soil pipes, flues, rooflights) or where a longer-lasting membrane finish is a priority.

EPDM can be a good choice for extensions and garages, as it is less likely to crack or delaminate with age. Felt remains the standard for straightforward re-roofing jobs where cost is the main consideration and the deck is in good shape.

What the Work Actually Involves

A flat roof job is not just laying a membrane over the old surface. Done properly, it involves stripping back to the structural deck, inspecting the timber or concrete beneath, correcting any falls, and only then fitting the new system. Skipping any of those steps is why many flat roofs fail prematurely.

Deck inspection. Once the old covering is stripped, we check the deck boards or concrete base for rot, movement or soft spots. Damp timber decking must be replaced before anything goes over the top of it. Missing this step can cause a new roof to leak early.

Fall correction. A flat roof is never truly flat - it needs a minimum fall of 1:80 to drain properly. If the fall is insufficient, water ponds and accelerates membrane degradation. Where falls need correcting, we use tapered insulation board or reposition the firring pieces to create the correct gradient before the membrane goes down.

Membrane installation. The chosen membrane is laid to the manufacturer's specification. Joints and laps are critical - a correctly bonded or torched lap is what keeps the roof watertight at its most vulnerable points. Edges are turned up and dressed to upstands, parapet walls or fascias to prevent water tracking back under the covering.

Detailing. Penetrations, corners, outlets and edges are where most flat roofs fail. Proper detailing means cutting and bonding collar pieces around pipes, forming internal and external angles correctly, and making sure every outlet is clear and flows freely.

Handover. Before we leave, we check the whole roof surface and every detail, clear the gutters and outlets, and make sure you can see the finished job for yourself.

How to Tell Your Flat Roof Needs Attention

Not every flat roof problem means a full replacement. These are the signs worth acting on before they become expensive:

Damp patches or staining on ceilings below the roof
Blistering, cracking or splitting on the surface of the felt
Pooling water that does not drain within 24 to 48 hours of rain
Felt that has lifted or pulled away from an upstand or edge trim
A roof that is more than 15 to 20 years old and has never been replaced

A repair is often possible if the membrane is mostly sound and the deck beneath is dry. If the felt has cracked through multiple layers or the deck has taken on water, a full strip and replacement is usually the more cost-effective long-term answer.

How a Flat Roofing Job Runs

Survey. We visit the property, inspect the roof from the surface down, check the outlets and upstands, and give you a clear account of what we found and what we recommend. We do not push for a replacement if a repair will do the job.

Scheduling. Flat roofing needs a dry spell to be done properly. We plan the work around the forecast and let you know in advance. Larger or more complex roofs will take longer.

The work. We strip, inspect, repair or replace the deck as needed, then install the new membrane with all associated detailing. Access is usually via ladder and roof boards. For roofs over a certain height or where there is no safe working platform, scaffolding may be required - we will tell you at survey stage if that applies.

Cleanup and sign-off. All stripped material is taken away, gutters are cleared, and we walk you through the finished roof before we go.

Access, Scaffolding and Permits

Most flat roof work on domestic extensions and garages in Cambridge can be reached safely with ladders and roof boards. Where the roof is over a storey high or sits above an occupied space with no safe perimeter, a scaffold platform may be needed. This adds to the overall cost and needs to be factored into any quote. Permits are not normally required for flat roof replacements on existing buildings, but if you are changing the height or adding a rooflight, planning rules may apply - worth checking with the local planning authority if you are unsure.

What Flat Roofing Costs in Cambridge

Flat roof replacement costs in Cambridge typically fall between £70 and £120 per square metre for a felt system, and between £90 and £150 per square metre for EPDM rubber, depending on deck condition, access and detailing complexity. A standard garage roof of around 20 square metres commonly costs between £1,400 and £2,500 all in. A larger extension roof of 40 to 50 square metres will often run from £3,000 to £6,000. These are honest typical ranges - the actual price depends on what we find when we strip back, and any deck repairs needed will be additional if the damage is only visible once the old covering is off.

Repairs to isolated splits or lifted edges start from around £150 to £300 for a minor patch, rising to £500 or more if a section of membrane needs replacing. A repair that keeps failing is usually a sign that the whole roof needs addressing.

Areas We Cover

We carry out flat roofing work throughout Cambridge and the surrounding area, including nearby towns and villages such as Ely, Newmarket, St Ives, Royston and Over. If you are unsure whether we cover your location, call us and we will tell you straight away.

Get a Survey Booked

If your flat roof is leaking or you think it is coming to the end of its life, call us to arrange a roof survey. We will give you an honest assessment and a clear price before any work starts.

Itemised quote
Materials, labour, scaffold broken out

Fixed start date
With a daily schedule

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Questions

What people ask first.

A new pitched roof on a typical three-bedroom semi in Cambridge generally costs between £5,500 and £10,000. The final price depends on the roof area, pitch, the material chosen (slate costs more than concrete tile), and how much structural timber work is needed. Larger properties with dormers, valleys or chimneys will sit toward the higher end or above it. A site visit is needed for an accurate figure.

For a standard semi-detached or terraced house, budget between £5,500 and £10,000 for a concrete or clay tile replacement, or £8,000 to £15,000 for natural slate. These figures include scaffold, stripping the old covering, new felt underlay and battens, lead flashing and ridge work. The final cost depends on roof size, the chosen material and what is found in the timbers once the old covering is stripped.

Most straightforward repairs - replacing slipped tiles, re-bedding ridge tiles or repointing chimney flashing - fall in the range of £150 to £600. More involved work such as replacing the felt on a flat roof extension or carrying out extensive leadwork will cost more, often £700 to £1,500 depending on size and materials. Every job is different, so the only reliable figure comes after a proper inspection.

For a standard felt system, expect to pay roughly £70 to £120 per square metre. EPDM rubber typically runs £90 to £150 per square metre. A typical garage roof of around 20 square metres usually costs between £1,400 and £2,500 all in, though deck repairs found once the old covering is stripped will add to that figure.

On a typical Cambridge semi-detached house, a full replacement of fascias, soffits and guttering on all elevations usually costs between £900 and £1,800. The final price depends on the size of the property, the number of elevations that need attention, and the profile and colour of uPVC you choose. Larger or more complex properties will cost more. Get a proper look at the job before committing to any figure.

Replacing a full set of chimney flashings in new lead typically costs between £350 and £700 on a standard stack, depending on the size of the chimney and how easy it is to access from the roof. If the existing lead can be re-fixed and re-pointed rather than replaced, the cost is lower, often £150 to £300. The current price of lead as a material affects any quote, as it is sold by weight and the metal price moves.

A typical domestic chimney rebuild in Cambridge, taken down to roof level and rebuilt with new lead flashings, generally falls between £1,500 and £3,500. The main variables are the size and height of the stack, how many flues it contains and whether scaffold is needed for safe access. We give a specific price once we have inspected the stack.

For a typical two-storey semi-detached in Cambridge, a full take-down to below roof level including scaffold, brickwork removal and making the roof good usually costs between £1,500 and £2,200. A larger stack or difficult access will push the price higher, so get an itemised quote once someone has seen the job. Waste removal and skip hire should be confirmed as included or excluded before you agree to any price.

Flat Roofing in Cambridge

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How we handle flat roofing