Can you find an underfloor heating leak without digging up the whole floor?

Yes, and that is the whole point of the method. Loop isolation removes most of the floor from the search, thermal imaging maps the pipe route and the saturation, and tracer gas on the drained loop takes it from an area to a point. One small opening is then made at that point.

How do I know whether the leak is in the floor or at the manifold?

By how the loops behave. One loop that never comes up to temperature while the others do puts the loss in that loop under the screed. Every loop heating evenly while the pressure still falls points at the manifold, the primaries or somewhere else on the system, and none of that needs the floor opened.

Will the repair leave a visible patch in my tiles?

Not if the tiles can be matched or if spares were left from the build, which is worth checking before we start. We relay and grout to match, and we will tell you honestly before cutting whether an exact match is likely. On engineered board, planks can sometimes be lifted and refitted intact; on click systems near the middle of a room, they sometimes cannot.

Can a screed floor be repaired the same day?

The pipe repair, usually. The floor needs the screed repair to cure before the finish goes back, and the heating should be brought back up gradually rather than straight to full temperature. Rushing that is what cracks the repair and the tile over it.

My electric underfloor heating seems to be leaking. Can you help?

Electric mat and cable systems contain no water, so they cannot leak. If the floor is wet, the source is plumbing elsewhere — a bathroom above, a concealed supply run, or a waste. That is an ordinary hidden leak investigation rather than a UFH job.

Repairs

Underfloor Heating Leak Repair in London

The failing loop is identified at the manifold before anything is touched, the leak is pinpointed through the screed with thermal imaging and tracer gas, one small core is taken at that point, the pipe is jointed or the loop re-run, and the screed and floor finish are reinstated by us.

Flooring and plaster being made good after a leak repair

What the job includes

Manifold inspection and loop-by-loop isolation to identify the failing circuit
Pressure test of the isolated loop to confirm the loss is in the floor
Thermal imaging to map the pipe route and pinpoint the saturation bloom
Moisture mapping across the slab to separate the wet zone from the pipe route
Non-invasive tracer gas on the drained loop to get from an area to a point
Pipe route marked before any cutting, so the core misses adjacent runs
Single small core or cut-out, buried-grade repair coupler, or loop re-run where needed
Screed reinstated to correct depth and level, finish relaid, and the floor brought back up to temperature gradually

No find, no fee · £150 per hour. The rate is fixed before we attend and does not rise for a difficult property, an awkward access or an evening visit. The total depends on how long the job takes; the rate cannot change.

First, find out whether the floor is involved at all

A large share of the calls we take about underfloor heating leaks turn out to be at the manifold, in the cupboard, entirely reachable without touching the floor. The difference shows in how the loops behave.

Pressure falling and one loop never comes up to temperature while the others do: the loss is in that loop, in the floor.
Pressure falling and every loop heats evenly: the loss is most likely at the manifold, on the primaries feeding it, or elsewhere on the heating system entirely. Check the cupboard floor, the manifold body, the actuator seats and the flow meters before anyone mentions a core drill.
Pressure rising when hot and falling below normal when cold: that is an expansion vessel, not a leak. Ruling it out costs nothing and saves a great deal.
Damp at the perimeter of the room, at a door threshold, or at the edge of the screed: water travelling on top of the insulation and escaping where the screed stops. The defect is somewhere upstream of that, not at the wet edge.

More on the pattern at I think my underfloor heating is leaking and a warm patch on the floor.

Why a UFH leak has to be pinpointed rather than searched for

A wet radiator circuit runs in a void you can open. A UFH circuit is a continuous loop of plastic pipe, usually 16mm, buried in screed and covered with tile, engineered board or resin. There are no joints in a correctly installed loop — it runs from the manifold, around the room and back — so a defect is either a manufacturing fault, a nail or screw driven through it after the screed went down, damage during the build, or a failure at the manifold connection.

That means guessing is ruinous. Opening a screed floor in the wrong place costs you the screed, the floor finish, the drying time and the room, and gets you no closer. Pinpointing is not a luxury on this job; it is the entire economics of it.

How we pinpoint it

Manifold inspection and loop isolation. Each loop is closed in turn on both flow and return. When the pressure stops dropping, that loop is the one. This alone removes most of the floor from the search.
Pressure test the isolated loop so the loss is proven in that circuit and not inferred.
Thermal imaging with the loop charged. The camera reads the pipe route through screed and tile as a set of warm serpentine lines, and it reads the leak as a distortion in that pattern — a bloom where hot water is saturating the screed rather than staying in the pipe. This is also how the pipe centres and the route are mapped, which matters later when the core is cut.
Moisture mapping across the slab to establish where the wet zone actually is versus where the pipe is.
Tracer gas on the drained loop. The loop is emptied and a hydrogen and nitrogen mix is pushed in. The gas escapes only at the defect and rises through screed, tile grout and floor joints, where a surface probe finds it. This is the method that gets you from an area to a point, and it is non-invasive — nothing is opened to run it.
Mark the point and the pipe route on the floor before any cutting, so the core is placed between pipe runs and not across a second one.

The repair

Once the point is marked, a single small opening is made — a core or a cut-out through the finish and the screed down to the pipe, sized to give working room and no more. The damaged section is cut out and a proper buried-grade coupler is fitted, or, where the damage is near the manifold or the loop is compromised in more than one place, the loop is abandoned at the manifold and re-run.

The repaired joint is pressure-tested and held before anything is covered, with the opening still visible. Nothing goes back over an untested joint in a screed floor, because the next look costs the floor again.

Where a loop cannot sensibly be repaired — multiple defects, or damage at a point that cannot be reached without taking out a substantial area of finished floor — the honest answer is sometimes to cap that loop and extend an adjacent one, or to run a new loop in a routed channel. We will set out the options with what each one costs you in floor, rather than defaulting to the biggest job.

Putting a screed floor back, which is a building job

This is where most leak firms stop and where the real cost sits. A hole in a screed floor with underfloor heating in it is not filled with a bag of sand and cement and forgotten.

The opening is cleaned back to sound screed with a clean edge, not a ragged one.
It is reinstated with a compatible screed or a rapid-setting repair screed appropriate to the depth, the cover over the pipe and the finish going back on top. Cover over the pipe matters: too little and the floor cracks over the run.
The repair is levelled to the surrounding floor rather than proud of it, because a hump telegraphs through engineered board and cracks tile.
It is allowed to cure before the finish goes back, and the heating is brought back up gradually rather than switched straight to full flow temperature, which is what cracks a fresh repair.
Tile is relaid and grouted to match. Engineered board is refitted, and where a plank cannot be lifted without damage we say so before we cut rather than after.

All of that is in-house: the same firm that found the leak and repaired the pipe. That is unusual in this market, and on a screed floor it is the difference between a repair and a project.

What we find in London

New-build flats and recent conversions

Wet UFH in a sand-cement or flowing anhydrite screed over insulation, manifold in a utility or hall cupboard. The most common defects are a fixing driven through a loop after the screed cured — a kitchen unit leg, a door threshold strip, a skirting fixing — and a manifold connection that was never fully made.

Basement conversions

UFH over a new slab with tanking underneath. Water cannot drain anywhere, moisture readings are complicated by the tanking, and the build-up is often thin, which changes how the repair is made.

Period houses with a new rear extension

The extension has UFH in screed and the rest of the house has radiators, all on one system. A pressure drop gets blamed on the new floor when it is frequently an old radiator tail in the original house. Sectioning the system before touching the new floor is the first thing we do here, every time.

Electric underfloor heating

Worth saying plainly: electric mat systems do not contain water and cannot leak. If you have electric UFH and a damp floor, the water is coming from somewhere else, and that is a different investigation — see water leak repair.

What you can do before we come

Photograph the manifold, including the labels on the loops, so we know the layout before arrival.
Note which rooms heat and which do not, and how long each takes.
Note the pressure cold and after an hour of running.
Find the floor plan or the UFH installation drawing if you have one from the build. A loop layout drawing saves real time, and time is the thing you are paying for.
Keep the heating on. A cold loop is much harder to image than a hot one, and asking you to turn it off before we arrive would be the wrong advice.

Terms

£150 per hour, fixed before we attend and unchanged for a difficult property, an awkward access or an evening visit. The total depends on the hours and on what the floor reinstatement needs — a core in a tiled utility and a repair under a resin floor in a basement are not the same job, and we will not pretend otherwise before seeing it. No find, no fee: if we do not locate the leak, you do not pay for the time spent looking. A written leak detection report, set out for a trace and access claim, is part of the job. More at insurance claims and pricing.

Frequently asked

Can you find an underfloor heating leak without digging up the whole floor?: Yes, and that is the whole point of the method. Loop isolation removes most of the floor from the search, thermal imaging maps the pipe route and the saturation, and tracer gas on the drained loop takes it from an area to a point. One small opening is then made at that point.
How do I know whether the leak is in the floor or at the manifold?: By how the loops behave. One loop that never comes up to temperature while the others do puts the loss in that loop under the screed. Every loop heating evenly while the pressure still falls points at the manifold, the primaries or somewhere else on the system, and none of that needs the floor opened.
Will the repair leave a visible patch in my tiles?: Not if the tiles can be matched or if spares were left from the build, which is worth checking before we start. We relay and grout to match, and we will tell you honestly before cutting whether an exact match is likely. On engineered board, planks can sometimes be lifted and refitted intact; on click systems near the middle of a room, they sometimes cannot.
Can a screed floor be repaired the same day?: The pipe repair, usually. The floor needs the screed repair to cure before the finish goes back, and the heating should be brought back up gradually rather than straight to full temperature. Rushing that is what cracks the repair and the tile over it.
My electric underfloor heating seems to be leaking. Can you help?: Electric mat and cable systems contain no water, so they cannot leak. If the floor is wet, the source is plumbing elsewhere — a bathroom above, a concealed supply run, or a waste. That is an ordinary hidden leak investigation rather than a UFH job.