What Actually Changes the Price of a Leak Detection Survey

Price follows time, and time follows the building

Nobody sells leak detection by the hour of instrument use. What is being priced is a prediction: how long will it take, in this building, to eliminate the things that are not causing the problem and then locate the thing that is. The equipment matters less to that prediction than most people assume, because the same thermal camera and the same correlator are used on a job that takes ninety minutes and on one that takes two days.

What differs is the property. A leak in a 1970s house with suspended timber floors, one heating zone and a visible meter is a different commercial proposition from the same leak in a third floor conversion flat with a screeded bathroom, two heating circuits, a shared riser, a tenant who works days and an agent who needs a written finding. Neither is harder to understand. One simply contains far more things to rule out before anything can be ruled in.

Six variables account for nearly all of the spread, and they are also the six things you can describe over the phone to get a quote that will hold.

Variable	What it does to the survey	Direction on price
Construction and floor build up	Decides which methods work and how much signal reaches the surface	Solid and screeded floors push it up
Number of systems in play	Each candidate is a separate isolation and test before locating starts	Every extra system adds time up front
Access	Governs how much booked time is spent working rather than waiting	Tenanted and communal access push it up
Whether the finish has to come down	Turns a non invasive survey into an invasive one	Adds a separate cost line, not a larger survey fee
Reporting standard	An evidential report is drafting work after the visit	A modest fixed element; omitting it costs more later
Fee model	Decides who carries the risk that the leak is a difficult one	Changes the shape of the bill rather than the average

Construction and floor build up

This is the largest single variable and the one clients most often leave out. What sits between the pipe and the instrument decides which methods are viable and how long the locating stage runs.

Solid floors and suspended timber behave differently

A suspended timber floor over a ventilated void is the cooperative case. Sound travels, heat travels, boards lift, and a pipe run can often be inspected directly once a small area is opened. A solid floor is the opposite: the pipe is embedded and everything has to be inferred from what reaches the surface.

Between them sits the case that causes most overruns: a suspended floor that has been overlaid. Battens, insulation, a plywood deck, levelling compound and an engineered board over an original joisted floor produce the access problems of a solid floor and the routing uncertainty of a timber one. None of that is visible from the doorway, which is why a photograph of a lifted threshold strip is worth ten minutes of description.

Screed depth and what it does to the thermal image

Thermal imaging does not see pipes. It sees surface temperature, and it infers what is beneath from the pattern. Depth, insulation and floor covering all blur that pattern, and they do so progressively: a warm pipe under 40mm of sand and cement under vinyl produces a sharp signature, while the same pipe under 75mm of insulated screed under natural stone produces a soft gradient that could be almost anything.

When the thermal image stops being decisive, the job moves to tracer gas, which is more definitive and takes longer because the circuit has to be drained, charged and then recommissioned. That method shift, rather than any change in hourly rate, is what converts a half day survey into a full one, and it is decided by the floor build up rather than by anybody's preference.

How many systems have to be eliminated

A wet patch on a ceiling is not a leak. It is a symptom with a list of candidate sources, and the survey has to work down that list. The length of the list is set by the building, not by the symptom, and it is the second biggest driver of time.

The candidates behind a typical wet patch

• The cold mains supply, tested by meter isolation over a fixed interval with every outlet closed.
• The heating circuit, isolated separately with the filling loop disconnected and the pressure decay watched.
• Waste and soil pipework, which leaks only in use and needs a load test rather than a static one.
• Rainwater ingress through roof, parapet, window or facade, which follows weather rather than occupancy.
• Condensation, ruled in or out by ambient temperature, humidity and surface readings rather than leak instruments.
• In a flat, all five again in the property above, which is a separate visit and a separate permission.

A house with one bathroom and a combi boiler might have three live candidates. A converted flat under another flat, with a flat roof above, a shared riser and communal heating, can easily have eight. That is not a harder problem intellectually, simply four times the elimination work, and it is why the same symptom is quoted at very different figures by two honest firms.

The cost of not eliminating

The temptation, when a survey is priced tightly, is to skip the eliminations and go straight to the most likely candidate. It is a false economy, and an expensive one when a third party is involved. The Financial Ombudsman Service's guidance on gradual damage is a reminder of why: buildings policies respond to sudden escapes and generally not to deterioration over time, and the difference between the two is established by evidence rather than assertion. A survey that recorded which systems were eliminated, on what readings, is evidence. A survey that went straight to the bathroom and found damp plaster is not.

Access, and everything that word hides

Access sounds like a logistics issue and is really a time issue. Booked hours are the same whether spent testing or waiting outside a locked communal door, and a quote has to assume one or the other.

The recurring London cases are variations of one problem: the survey needs to be in more than one place and somebody else controls one of them. A leak presenting in a ground floor ceiling frequently needs access to the flat above, sometimes the one above that, and occasionally a communal riser cupboard whose key sits with a managing agent. Each is a permission, and permissions run on other people's timetables.

Tenanted, occupied and communal access

A tenanted property adds notice periods and a working day that may not overlap the survey window. An occupied one adds the constraint that appliances cannot always be shut down for the length of a static test, which matters because a dishwasher on a timer invalidates any meter reading taken across it. None of this changes the technical work; all of it changes how many visits the work takes, and a second visit is the most expensive thing that can happen to a survey fee. Confirm who holds which key before the date is set.

Whether the finish has to come down

Most surveys are non invasive by design; that is the point of the instruments. But some leaks can be located to within a small area and no closer, and at that point somebody has to decide whether to open up.

The distinction worth holding is between minimal access and opening up, and it should be explicit on the quote rather than assumed.

Minimal access	Opening up
Lifting a board, removing a bath panel or a section of boxing	Cutting out plaster, breaking screed, removing a ceiling
Reversible within the visit	Not reversible; reinstatement follows
Normally inside the survey fee	A different trade and a different invoice

Where trace and access cover sits

This is also the point where a buildings policy becomes relevant. The Association of British Insurers notes on its guidance about burst pipes and water leaks that an insurer may cover the cost of locating, accessing and repairing a leak along with the resulting water damage, but that trace and access cover is not always included as standard and is worth checking on the policy. Where it is included, the detection fee and the making good of access damage are frequently recoverable while the failed pipe itself is not, which is a further argument for having those figures itemised rather than merged. Our trace and access page covers what that extension typically does and does not pay for.

Whether the report has to satisfy a third party

A homeowner who simply wants the leak fixed needs a location and a recommendation. A landlord, a freeholder, a managing agent or a loss adjuster needs a document that will survive being disagreed with, and that is a different deliverable.

Writing to evidential standard is work done after the site visit: readings transcribed with units and times, photographs referenced to a plan, methods recorded in sequence with the reason for each change, access limitations stated honestly, and a finding that separates origin from cause. It is not a large cost, but it is a real one, and a firm that has not priced it will either not produce it or produce something that does not do the job. What the document has to contain is set out in the leak report a landlord or managing agent can actually use.

The cost of omitting it is asymmetric. A report that is not needed has cost a modest fixed sum. A report that was needed and does not exist means a second survey, at a point when the evidence has usually been disturbed by drying, repair or reinstatement.

Hourly rate and fixed fee behave differently on a hard leak

Two firms can charge the same amount on average and produce completely different bills on the same job, because the fee model decides who carries the risk that the leak is a difficult one.

Fee model	On a straightforward leak	On a hard to trace leak	Who carries the risk
Hourly rate	Cheapest outcome, because you pay only for the time used	Open ended; the meter runs while the difficulty is discovered	The client
Fixed fee agreed in advance	Slightly more than the hourly equivalent	Capped; the overrun is absorbed	The contractor
Fixed fee with a stated scope and a variation clause	Comparable to a fixed fee	Capped up to the scope, with any extension agreed before it is incurred	Shared, with a decision point
No find, no fee	Priced above a plain fixed fee, because the successes fund the failures	No charge if nothing is found, with the definition of found doing the work	The contractor, subject to the wording

No model is dishonest and none is universally better. What matters is that the model is stated before attendance and that the client knows which one they are buying. An hourly rate is the right answer on an accessible house with one heating zone and a visible meter. It is the wrong answer on a screeded flat with five candidate systems, because the very features that make the job uncertain are the ones that make an open ended bill uncomfortable.

What no find, no fee does to the arithmetic

No find, no fee is genuinely useful and frequently misunderstood. The price includes the cost of the jobs where nothing is found, so it sits above a plain fixed fee by design. The operative question is what counts as a find: a firm that treats a narrowed area as a find and a firm that requires a marked point are offering different products at similar prices. The practical detail is set out in what a no find, no fee guarantee actually covers.

Reading a quote, and what published rates do not tell you

Published market data is useful for calibration and useless for a specific property. Checkatrade's water leak detection cost guide gives an average of £162, a typical range of £115 to £234, and a full spread across recorded jobs of £80 to £1,600, with hourly rates of £95 to £145 and an emergency call out of £100 to £120. Its plumber cost guide separately puts general plumbing at an average of around £50 an hour with a day rate averaging £350, and emergency work substantially higher.

Those numbers are worth knowing for one reason: the figure most often quoted in conversation, that detection costs around £500 on average in the UK, appears in no published dataset we have been able to find. The published averages sit well below it and the published range runs far above it, which tells you an average is the wrong tool for this decision.

What replaces it is a quote that itemises. Before accepting one, the following should be explicit.

• The fee model, and what happens if a defined scope is exceeded.
• Which systems will be tested, and how many properties the visit covers.
• Whether a written report is included, and whether it states cause as well as origin.
• Whether minimal access is included, and where the line sits between that and opening up.
• Whether repair is quoted separately, and whether reinstatement is anyone's responsibility.
• What happens on a second visit if access is not available on the day.

Our fee is fixed, agreed before we travel and quoted separately from any repair, and we do not publish a figure that has not seen the property. Our pricing page sets out how a survey is scoped, and our leak detection service describes the sequence. Where you are comparing quotes that appear to be for the same work, why leak detection quotes vary so much in London is the companion piece.