Underfloor Heating Leak Detection

An underfloor heating leak hides better than any other heating fault. The pipework sits inside or under the screed, there is no hatch to lift and no radiator to inspect, so the first you usually know about it is a boiler that will not hold pressure or a floor that feels wrong underfoot. After more than 30 years finding leaks across Cornwall and Devon, we have seen too many UFH floors ripped up room by room on guesswork.

That is the one outcome we exist to prevent. We locate the leak first, non-invasively, then the repair opens a single small area of floor. No call-out fees, a fixed price agreed up front, and No Find, No Fee on residential leak detection (subject to terms).

🚨 Signs your underfloor heating is leaking

Wet underfloor heating is a sealed circuit, so when water escapes, the system tells you in its own way. The three signs we are called out for most:

• Pressure keeps dropping. The boiler gauge falls, you top it up, and within days it has fallen again. Heating manufacturers such as Vaillant and Ideal both list a hidden leak as a common cause of repeated pressure loss in a sealed system (a faulty expansion vessel or pressure relief valve can do the same, which is why we test before anyone touches the floor).
• Cold zones in a heated floor. Part of a room stops warming up while the rest works. A loop that is losing water often stops circulating properly, and the cold band can sit close to the leak itself.
• Damp patches, lifting flooring or musty smells. Moisture working up through the screed shows as dark patches on stone or tile, cupping or lifting in wood and laminate, or a damp smell that will not air out.

An unexplained rise in usage on a metered supply backs up the picture. If you are seeing these signs and want to understand the damage side before booking anyone, our guide to what happens when underfloor heating leaks and what to do walks through it step by step, and we cover the signs of an underfloor heating leak in more detail too. If your boiler is losing pressure but the radiators are the suspect rather than the floor, that is a job for central heating leak detection instead.

🧱 Why underfloor heating leaks are different

With a radiator circuit there is usually somewhere to look: valves, joints, visible pipe runs. Underfloor heating gives you none of that. The pipe is stapled or clipped down to the insulation, the screed is poured over the top, and the finished floor goes on. Once the room is built, the entire circuit is sealed inside the structure with no access hatches anywhere along it.

Installer guidance from the major UFH manufacturers is to run each loop as one continuous length of pipe back to the manifold, precisely because any joint buried in screed is a known failure risk. Where leaks do start, it is typically at a fixing or joint that should not be under the floor, at a point where the pipe was nicked during installation, or where later building work has put a drill bit or fixing screw through a loop.

The result is a leak you cannot follow by eye and cannot reach without breaking the floor open. Digging on a hunch means destroying finished flooring, screed and sometimes the surrounding loops, which is why blind exploratory work is the most expensive way to find a UFH leak. The same logic applies to any buried pipework, and our guide on how to find a water leak under a concrete floor explains why the floor itself should always be the last thing to come up.

🎯 How we find the exact spot without digging up the whole floor

Every survey follows the same structure, and the floor stays intact while the kit does the searching:

Where it helps, we add acoustic listening and moisture mapping to cross-check the result. The point of using more than one method is simple: when the floor is opened, it is opened once, in the right place.

⚡ Wet or electric underfloor heating? An honest note

Our detection work covers wet (water) underfloor heating: the systems where a boiler or heat pump circulates heated water through pipe loops in the floor. Electric underfloor heating uses heating cables or mats and carries no water at all, so it cannot spring a water leak. If an electric floor has stopped heating, the fault is electrical and the right person is a qualified electrician, not a leak detection engineer. We would rather tell you that on the phone than charge you to find it out, so let us know which system you have when you call. If water is appearing near an electric floor, the source is usually a plumbing or heating pipe nearby, and that we can find.

🔧 Repair access: one tile, not the whole floor

Because the leak is located before anything is opened, the access work is small and precise: typically one tile, one board or one small section of screed directly over the breach, rather than a trench across the room. The exposed pipe is then repaired and the loop pressure tested before the floor is made good. That is the whole value of professional underfloor heating leak detection in one sentence: you pay once to find the leak exactly, instead of paying for a floor that was opened in the wrong place.

🛡️ Insurance and trace & access cover

Most UK buildings insurance policies include trace and access cover. In plain terms, it usually pays for professionally locating the leak and making good the damage caused by getting to it, which matters with underfloor heating because the access damage (floor finish and screed) is most of the cost. It does not always cover repairing the pipe itself, and policy limits vary, so check your own wording. Our plain English guide to what trace and access cover is walks through it, and our trace and access service handles the detection and the insurer-ready documentation in one visit.

📋 What to expect on the day

An underfloor heating leak survey is not disruptive, and a few minutes of preparation helps us work faster:

• Know where your manifold is (often in an airing cupboard, utility room or under the stairs)
• Note how quickly the boiler pressure drops after a top-up, since the rate tells us how big the leak is
• Run the heating for an hour or two before we arrive if you can, because warm loops show up far better on the thermal camera
• Clear access to the rooms with cold zones or damp patches
• Dig out any installation plans or photos from when the floor went in, if you have them (helpful, never essential)

On the day we isolate, test, scan and mark the leak position, then talk you through exactly what we found and what should happen next. The price is the one agreed before we arrived.