No strip-off, no skip
The existing covering stays where it is, so the strip-off labour, the skip and the disposal charge all come off the quote. That gap is the main reason refurbishment costs less than replacement.
Roofing Solutions / Flat Roof
Flat Roof Repair and Waterproofing in London
We install, repair and refurbish flat roofs across London using GRP, EPDM, torch-on felt and HYDRONYLON. Every roof is finished to a 10-year workmanship guarantee.
Get a site surveyMost London flat roofs can be sealed, not replaced
This page is for anyone in South and West London with a flat roof that leaks, ponds or is coming to the end of its life, whether that is a rear extension, a garage, an office block, a retail unit or a warehouse. K & M Roofing Solutions repairs, refurbishes and replaces flat roofs on all of them, and the same team surveys the roof, does the work and signs it off.
What decides between a repair, an overlay and a full replacement is the structure underneath rather than the age of the covering. Where the deck is sound and the insulation is dry, the existing covering can usually stay and be waterproofed over, which takes the strip-off, the skip and the disposal charge out of the quote. Where the deck has rotted, the insulation is saturated or the falls were never right, no covering fixes that, and we will tell you so at survey rather than after.
On site the job is planned around the building staying in use. An overlay is normally two to four days on a domestic roof and the building carries on underneath; a strip and replace runs longer because the deck is opened up and has to be programmed around the weather. Either way we agree access and working hours before we start, sheet up what needs protecting, and clear our waste at the end of each day.
Occupied offices, shops, warehouses and blocks of flats are a large part of this work, and the way a job is phased around a building that cannot close is set out on our page for commercial flat roofing in London.
A flat roof also lasts considerably longer when the outlets and gutters serving it are kept clear, which is the cheapest single thing an owner can do and the reason we offer planned roof care and maintenance across South and West London.
The single largest concentration of this work is on our own doorstep, on the postwar rear extensions that almost every Croydon terrace and semi has, which is set out on our page for roofing in Croydon, CR0.
Where the plan is to walk on the roof rather than just keep the rain off it, the waterproofing is still the part that decides everything, and our page on roof terraces, balconies and decking explains why the layer under the boards is put right before anything is built on top of it.
Benefits
Why an overlay beats a strip and replace
The deck is never opened
A replacement leaves your deck exposed for a period, sometimes several days. An overlay never creates that window, so the weather is never a risk to what sits under the roof.
Days rather than weeks
Most domestic overlays are finished in two to four days and the building stays open and occupied throughout. A full replacement runs considerably longer.
No Part L insulation upgrade
Replacing more than half a covering generally triggers a Building Regulations insulation upgrade. An overlay onto a sound roof usually does not, and that is a real cost line rather than a technicality.
What we offer
Flat roofing work we take on
From a single leak traced and sealed to a full replacement with new insulation, on domestic, commercial and industrial roofs.
Leaking flat roof repair
We trace where the water is actually getting in, which is rarely where the stain appears inside, then seal the detail rather than patching over it.
Liquid overlay refurbishment
A cold-applied waterproofing system taken over the existing roof, up the upstands and into the outlets, with no strip-off.
See how liquid applied waterproofing worksFull flat roof replacement
Where the deck or insulation is beyond saving, we strip back, renew the structure and build up a new warm roof to current building regulations. It costs more than an overlay because strip-off, disposal and the Part L insulation upgrade all come back into the job.
See what a flat roof costs in LondonFalls, ponding and outlets
Correcting shallow falls with tapered insulation and renewing blocked or undersized outlets, so water leaves the roof instead of sitting on it.
Drone survey before we quote
On tall, steep or fragile roofs we survey from the air first, so the report is based on what the roof actually looks like rather than guesswork.
See how a drone roof survey worksGuttering and rainwater outlets
A flat roof is only as good as the drainage around it, so we repair, replace and clear the guttering and downpipes that serve it.
See our guttering servicesScope
What we cover
- New flat roof installation
- Full strip-off and replacement
- Liquid overlay refurbishment
- Leak tracing and repair
- Ponding water and falls correction
- Insulation upgrades and warm roof build-ups
- Parapet walls, upstands and coping stones
- Rooflights, outlets and rainwater detail
Materials
Which flat roof system is right for you
Four systems cover almost every flat roof in London. The right one depends on the state of the deck, how the roof is used and the budget, and we explain the trade-offs honestly before any work begins.
HYDRONYLON
ETA-23/0735A liquid-applied waterproofing system, applied cold over the roof already in place, curing into one continuous layer with no seams. It is certified to ETA-23/0735 and K & M Roofing Solutions is a certified applicator, which is what allows a separate 10-year product guarantee from HYDRONYLON LTD alongside our own 10-year workmanship guarantee. Best for a sound roof that leaks but does not need stripping, and usually the cheapest route because there is no strip-off, skip or disposal.
What ETA-23/0735 certification covers and which substrates suit itFibreglass (GRP)
Seamless finishGlass reinforced plastic is laid wet and cures into one continuous surface with no joins or seams. It gives a hard, smooth finish that takes foot traffic well, which makes it a good choice for balconies, dormers and any roof that gets walked on. It has to go down on a clean, dry deck in mild weather, so installation is weather dependent and slower to schedule in winter. A well installed GRP roof can last decades, and it suits a new deck or a full replacement rather than an overlay.
EPDM
Durable rubberEPDM is a synthetic rubber sheet, usually laid in a single piece on a domestic roof. It stays flexible in heavy frost and does not soften in summer heat, so it copes well with the swing in London weather, and because it arrives as one sheet the joints are limited to the edges and penetrations. It is light, which helps on a deck that cannot take much extra load. It suits garages, sheds, extensions and larger simple roofs on a mid-range budget.
Three-layer felt
Building reg standardThree-layer felt is a vapour control layer, a reinforced underlay and a mineral cap sheet, bonded in turn. Building regulations require three layers over habitable rooms, so this is the standard specification for a bedroom or kitchen extension rather than a garage. It is a proven, well understood build that any competent roofer can maintain or patch later. It suits a full replacement on a tighter budget, particularly where the deck is being renewed anyway.
How it works
How our flat roof service works
1
Free site survey
We get onto the roof, or fly it by drone where access is difficult, and check the build-up, the falls, the outlets and whether there is trapped moisture. Most surveys take under an hour and cost nothing.
2
Report and itemised price
You get a written report with photographs of what we found and an itemised price covering labour, materials and access. It normally reaches you within two to three working days.
3
System and start date agreed
We talk through which system fits the roof and the budget, then book a start date around your access, parking and opening hours.
4
Preparation
We clean the roof back to a sound surface, cut out and make good any failed areas, and repair or renew decking where needed. On an overlay this ends with priming; on a replacement it ends with the new deck and insulation laid.
5
New waterproofing installed
Whichever system was agreed goes on, whether that is a liquid overlay applied cold over the existing covering or a new felt, EPDM or GRP build-up. Upstands, outlets and penetrations are detailed as part of the same operation. A typical domestic roof takes one to three days depending on size and weather.
6
Final check and guarantee
We inspect every detail and outlet, check the roof drains properly, clear all waste from site and issue your 10-year workmanship guarantee in writing.
Why choose us
Why customers choose K & M Roofing
01
Certified HYDRONYLON applicators, a system most London roofers cannot offer.
02
One team for the whole job, from survey to sign-off.
03
Rated 5.0 by 60 customers on Google.
04
Flat roofing is the core of what we do rather than a sideline, and we survey every roof ourselves before quoting.
05
Transparent pricing with no hidden costs, and a 10-year workmanship guarantee.
Where we work
Flat roofing in the areas we know best
Flat roof problems are not evenly spread. Each of these areas generates a different kind of job, and each has its own page setting out why.
- Roofing in Clapham: Rear additions, dormers and the flat-roofed extensions added to the mansion blocks facing the Common in the 1960s and 1970s, most of them now well past the life of their original covering.
- Roofing in Battersea: The 1980s riverside blocks whose original covering has run out, worked above residents who stay put, and the rear additions behind the SW11 terraces inland.
- Roofing in Balham: Parapets, coping stones and the hidden gutters behind them, which is where most SW12 water actually gets in, plus the question of who in a converted house is allowed to instruct the work.
- Roofing in Wandsworth: Shared valleys and linked drainage across terraced runs, and the large managed flat roofs on the mid-century blocks, where an overlay keeps residents in place.
- Roofing in Croydon: Our home ground. Postwar rear and side extensions carrying their original covering decades past its life, plus the managed flat and podium roofs in the town centre.
- Roofing in Wimbledon: The flat sections created by decades of extending and converting large SW19 houses, where one generation of work meets another and that is where water gets in.
- Roofing in Southwark: Warehouse conversions with terraces, rooflights and lift overruns, and Georgian roofs behind parapets that nobody sees until a ceiling stains below them.
- Roofing in Vauxhall and Nine Elms: Podium decks over occupied floors and profiled metal sheds on the industrial estates behind them, where booking the access matters as much as the specification.
- Roofing in Acton: Mostly slate rather than flat, so the flat roofing here is the rear additions behind the W3 terraces and the extensions built onto them since.
Knowledge
Read more before you decide
Common questions
Frequently asked questions
In most cases, yes. If the deck is sound and the insulation is dry, we clean and prime the existing covering and take a liquid-applied waterproofing system over the top, which avoids a full strip-off entirely. A free survey confirms whether the existing build-up can stay in place, and we will tell you plainly if it cannot.
Flat roofing is priced per square metre and the system drives the range: three-layer felt runs roughly £40 to £80 per square metre, EPDM roughly £80 to £120 and GRP roughly £100 to £150, with London labour typically 25 to 30 percent above the national average. A liquid overlay usually costs less than a full replacement because strip-off, skip hire and disposal all come out of the job. Access, roof size, insulation and the condition of the deck move the figure either way. We do not quote a price before seeing the roof, and the survey that produces the price is free.
It depends far more on the detailing and the deck than on the headline material. Three-layer felt commonly reaches 15 to 20 years, and EPDM and GRP often go longer where the deck is sound and the upstands and outlets were done properly. Any flat roof lasts longer if the outlets are kept clear, which is the single cheapest thing an owner can do. Our workmanship guarantee runs for 10 years and we do not make durability claims beyond that for the work we carry out.
It comes down to the state of the existing roof, how the roof is used and the budget. A liquid-applied system suits a sound roof that leaks and lets you avoid a strip-off, GRP suits a new deck and roofs that get walked on, EPDM suits simple domestic roofs where weight matters, and three-layer felt is the standard build over habitable rooms. We recommend one after the survey and explain why the others were ruled out.
Most domestic flat roofs are finished in two to four days, and an overlay sits at the shorter end because nothing has to come off first. Larger commercial roofs run longer and we phase them so parts of the building stay in use throughout. The work is cold applied, so there is no torch and no hot works, and we sheet up, agree working hours in advance and clear waste at the end of each day.
Every flat roof we complete carries a 10-year workmanship guarantee, issued in writing when we sign the job off. Flat roofs finished with HYDRONYLON also carry a separate 10-year product guarantee issued by HYDRONYLON LTD, which covers the system itself. The two are independent of each other, so the product guarantee stands whatever happens to the installer.
We stop, identify it and handle it properly rather than working around it. Older flat roofs, particularly bitumen sheeting and some older felts, can contain asbestos, and we remove and dispose of it through a licensed facility in line with Health and Safety Executive guidance. You receive the consignment documentation showing the waste was handled legally. This is also a strong argument for an overlay where one is possible, because leaving a sound asbestos-containing layer sealed and undisturbed avoids the removal entirely.
Ponding is water still sitting on the roof more than 48 hours after it stops raining. A shallow pool on a sound roof is not an emergency, but it is a warning: it usually means the falls are too shallow, the deck has sagged or an outlet is blocked, and standing water finds any weak joint and accelerates wear. We check the falls and outlets during the survey and correct them with tapered insulation or a new outlet, rather than simply waterproofing over the dip.
Yes, and most of our commercial flat roofing is done on buildings that stay open. A liquid overlay suits occupied premises because it is cold applied with no torch and no strip-off, which means no hot works permit, far less noise and no skip blocking the entrance. We agree access, parking and working hours with the building manager or managing agent before we start, and can phase larger roofs or work outside business hours.
Free on-site estimate
Let us talk about your roof
Tell us what is going on and we will arrange a free survey. No pressure, no hard sell, just honest advice and a clear price.
Kamil07593 196505
Mateusz07544 188268