We find the cause first
The survey establishes where water is actually entering before anything is priced, because a repair aimed at the stain rather than the entry point is a repair that comes back.
Roofing Solutions / Roof Repairs
Roof Repairs in London
A stain on the ceiling, a damp patch at the top of a wall or water coming in during heavy rain. Start here, work out what you are dealing with, and go to the page that covers it.
Get a free surveyStart here if you have water coming in and no idea why
If you are looking at a stain on a ceiling, a damp patch at the top of a wall or water coming through during heavy rain, and you do not yet know what is causing it, this is the page to start on. You do not need to know what kind of roof you have. Working that out is the first thing it does, and we cover South and West London from Croydon.
The reason to start here rather than on a service page is that the rest of this site is organised by roof type, and a leak does not introduce itself that way. Almost nobody searching for help with a leak knows whether the water is coming off a flat roof, a slate slope, a parapet, a terrace or a blocked gutter, and picking the wrong page wastes a reading and sometimes a survey.
One thing worth knowing before anything else: where the water shows up inside is very often not where it is getting in. Water enters at a defect, then travels along a rafter, a joist end, a wall plate or the top of a wall until something stops it, and the stain appears at that point rather than at the entry. It can surface a metre or more away, on a different elevation, a floor lower. That is why the first job on site is finding the entry point rather than sealing the wet-looking area, and it is why a repair that treated the stain tends to come back.
Before you accept anyone's diagnosis, it is worth knowing that a damp ceiling is not always a roof at all, and our guide to telling a roof defect from condensation, plumbing or a gutter sets out how the four are told apart.
If somebody has already told you that the roof needs replacing rather than repairing, that is a judgement with evidence behind it or it is a sales position, and how a surveyor actually makes that decision explains what the evidence should be.
For what the work costs once the cause is known, including the honest ranges and what moves them, our flat roof cost guide for London is the place to look rather than any figure quoted before a survey.
Benefits
How we deal with a leak
Repair before replacement
Where the structure underneath is sound we say so and repair it. A leak is not evidence that a roof is finished, and we will tell you when it is not.
Water coming in comes first
Active ingress into an occupied room goes ahead of planned work in the diary. If water is coming in now, phone rather than email so we can talk it through properly.
One team, survey to sign-off
The people who diagnose the leak are the people who repair it, so nothing is lost between a surveyor who has left and a fitter who was not there.
What we offer
Which roof is the water coming off?
You can usually tell from the ground or an upstairs window in a minute. Find the one that matches and follow the link, which goes to the page that covers repairing it.
A flat roof
The damp is in a back room, a kitchen, a utility or a bedroom over an extension, and there is something above it with no tiles on it that you cannot see from the pavement. Look down on it from an upstairs window: if water is standing in puddles a day after rain, or there are dark patches, splits or a bubbled surface, that is your source. Most London leaks into a back room start here.
See flat roof repair and waterproofingA pitched roof
The damp is upstairs or in the loft, and the roof above it is the sloping tiled or slated one you can see from the street. Stand across the road and look for a gap where a slate has gone, a ridge line that has stopped running straight, or a dark streak below a chimney. A leak that only appears in wind-driven rain from one direction usually belongs to this group.
See pitched roof repair and re-roofingA metal roof
Water is running down a wall or dripping in lines inside a unit, warehouse or shed with a ribbed metal roof. On these the water almost never comes through the middle of a sheet: it follows the rows of fixings, the overlaps between sheets, or the sealant around a rooflight, so the drips inside tend to appear in a regular pattern rather than at one spot.
See metal roof waterproofing and repairA terrace or balcony you can walk on
Decking or tiles over a room, with a door out onto it. This is a flat roof with a floor on top, and the waterproofing that matters is under the surface where nobody can see it, so the diagnosis is different from anything else on this list.
See roof terraces, balconies and deckingStill not sure, or it might be the gutters
Plenty of what gets reported as a roof leak is rainwater goods: an overflowing gutter soaking a wall, a joint that has opened, a downpipe running down the brickwork rather than into the drain. If the damp follows heavy rain and shows on an outside wall rather than a ceiling, start there.
See guttering repair and replacementScope
What to do now, before anyone arrives
- Move what matters out of the way, and put a container under the drip
- Pierce a bulging ceiling deliberately, over a bucket, before it bursts
- Turn off the electrics to that room if water is anywhere near a light
- Photograph everything, dated, inside and out: insurers ask later
- Note the weather each time it happens, and which wind direction
- Do not go onto the roof yourself, in the wet, to look
- Do not let anyone seal the stained area without finding the entry point
- Keep the receipt for anything you buy to limit the damage
Materials
What usually fails, by roof type
The recurring causes on London buildings, so you have some idea what you are looking at before anyone arrives. None of these can be confirmed from the ground, and the point of listing them is orientation rather than diagnosis.
Flat roofs
Details, not the middleSplits and open laps in an ageing covering, upstands that have pulled away where the roof turns up a wall, outlets blocked so the roof holds water instead of draining, and blistering where moisture is trapped under the surface. Flat roofs almost never fail in the open middle; they fail at the edges and the junctions.
See how flat roof faults are repairedPitched roofs
Fixings and flashingsSlates slipping because the nails have corroded rather than because the slate failed, ridge and hip tiles loose where the mortar has gone, cracked or missing flashings around a chimney, and valley gutters between two slopes that have rusted or filled with debris. Storm damage usually shows up here first.
See how pitched roof faults are repairedMetal roofs
Corrosion at the fixingsRust creeping out from around the fixings, seams and sheet laps that have opened as the metal expanded and contracted, and failed sealant at the flashings and rooflight kerbs. On an older industrial roof the sheet itself is often sound long after the details around it have gone.
See how metal roof faults are repairedParapets, chimneys and abutments
The most misdiagnosed of allOn a London terrace the leak is frequently not in the roof covering at all but at the top of a wall: an open coping joint, eroded pointing, a failed flashing where the roof meets a chimney or a neighbouring wall. Water enters above the roof line and runs down inside solid brickwork, which is why replacing the covering does not stop it.
Read why parapets cause so many London leaksHow it works
From your call to the repair
1
Tell us what you can see
Where the water shows, when it started, whether it follows rain or wind from one direction, and what is above it if you know. Photographs help more than a description. If water is coming in now, phone rather than email.
2
Free survey
We look at the roof, the roofline and the inside, and where the roof is steep, fragile or behind a parapet we survey it from the air rather than guessing from the ground. The aim is the entry point, not the stain.
3
You get the diagnosis in plain terms
What is letting water in, why it failed, and whether it is a repair or the start of a bigger conversation. Where the honest answer is that the covering is at the end of its life, we say that rather than selling a patch that will not hold.
4
Itemised quote
Priced from what the survey found and broken down by element, so you can see what the access, the repair and any making good each cost, and stage the work if it needs staging.
5
The repair
Carried out by the same team, with the working area sheeted and the waste cleared at the end of each day. Where a temporary measure is needed to stop water getting in before a permanent repair can be done properly, we do that first and say so.
6
Sign-off and guarantee
We show you what was done, with photographs where the work is somewhere you cannot see, and the repair carries our 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
Diagnosis before pricing on every leak, because a repair aimed at the wrong place is money spent twice.
05
Transparent pricing with no hidden costs, and a 10-year workmanship guarantee.
What our 10-year workmanship guarantee covers, how it differs from a manufacturer product guarantee, and what falls outside it.
Knowledge
Read more before you decide
Common questions
Frequently asked questions
Contain it, protect the electrics and record it. Put a container under the drip and move what matters out of the way. If the ceiling is bulging, pierce it deliberately over a bucket rather than waiting for it to come down on its own, because a bulge is holding water and it will fail eventually. Turn the power off to that room if water is near a light fitting or a socket. Then photograph everything with dates, inside and out, because that record is what an insurer asks for later. If water is actively coming in, phone rather than email: active ingress goes ahead of planned work in our diary.
Usually not, and this is the single most useful thing to understand about a leak. Water enters at a defect and then travels along whatever it meets, a rafter, a joist end, a wall plate or the inside of a wall, until something stops it. It appears at that stopping point. On a London terrace the entry can be a metre or more away, on a different elevation or a floor higher. That is why a repair aimed at the visible damp so often fails, and why the first job on site is tracing the path rather than sealing the symptom.
Look at the building from the pavement and from an upstairs window at the back. If you can see slate or tiles sloping up to a ridge, that is a pitched roof. If there is a rear extension, a garage or a dormer whose top you cannot see from the street and which has no tiles on it, that is a flat roof. Most London houses have both: a pitched roof over the front and a flat roof over whatever was added at the back, and it is the flat one that leaks more often. If you are still not sure, send us a photograph and we will tell you.
It depends on the structure underneath rather than on the age of the covering, and that is a survey question rather than a judgement anyone can make from a photograph. Where the deck or the timbers are sound and the fault is local, a repair is the right answer and it will hold. Where the deck has rotted, insulation is saturated or the same roof has been patched repeatedly and keeps failing somewhere new, a repair is money spent to delay the same decision. We will tell you which of those you have, including when the answer is that you do not need what you were expecting to pay for.
Some things yes, most things no, and the distinction matters. Making a roof safe and stopping water getting in can often be done in poor weather as a temporary measure. A permanent repair usually cannot: adhesives, sealants and liquid systems need a dry, prepared surface to bond to, and work forced onto a wet roof fails early. Where the honest sequence is a temporary measure now and the proper repair in a dry window, we say so rather than doing it badly once.
It depends what caused it, and the distinction insurers draw is between sudden damage and gradual deterioration. Storm damage, an impact or a one-off event is usually covered. A covering that has slowly reached the end of its life, or a fault that was there and was not dealt with, usually is not, because policies exclude wear and tear. Photograph everything with dates from the first day either way, keep receipts for anything you buy to limit the damage, and get the cause established properly, because a written diagnosis is what an insurer actually assesses.
Yes, and that is most of our repair work. We are not looking for a reason to condemn somebody else's roof: if the previous work is sound and the fault is elsewhere, that is what the survey will say. Where a repair we carry out sits alongside older work we did not do, we are clear about what our 10-year workmanship guarantee covers, which is our work rather than the roof as a whole.
Less than almost anyone fears, in the majority of cases, because most leaks are a failed detail rather than a failed roof. There is no useful rate to publish for a repair, because the work ranges from re-fixing a slipped slate to rebuilding an abutment, and access is often the larger part of the price on a two-storey house. Our survey is free and the quote that follows it is itemised, so you can see what the access and the repair each cost. For the ranges on larger flat roof work, and what moves them, see our flat roof cost guide.
On a terrace the covering is usually yours to your own boundary, but valleys, party wall stacks and shared parapets sit across both, and a leak in one of those affects both houses. In a converted flat or a block, the roof is almost always the freeholder or the management company rather than the leaseholder, and the lease settles it. We work for owners, leaseholders, freeholders and managing agents, and where a fault genuinely spans two properties we will say so in writing so it can be sorted out between you rather than argued about.
We work across South, West and Central London from our base in Croydon, including Clapham, Battersea, Balham, Wandsworth, Wimbledon, Southwark, Vauxhall and Acton, each of which has its own page. How far we travel depends on the size of the job rather than a line on a map, so a postcode outside that list is still worth asking about. Send us the postcode and we will tell you whether we cover it rather than booking a visit and cancelling it later.
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