In-Floor Heating near you

Paragraph 8.13 of Approved Document L Volume 1, the 2021 edition incorporating the 2023 amendments, states that all installed equipment in underfloor heating systems should be commissioned in accordance with BS EN 1264-4. It sits in the same commissioning section as the requirement that commissioning information provided to the dwelling owner should include details of the fluids used and their commissioned concentrations — the inhibitor and, on a ground loop, any antifreeze.

The sequence that standard sets out exists because a heated screed is a structural element that has to be brought up to temperature in a controlled way. The pipe is pressure tested and left under pressure while the screed goes down, so damage from a later trade shows up immediately. The screed then cures for the period its manufacturer specifies, with the heating off. Only then does a functional heat-up begin at a low flow temperature and rise in steps, holding at each, before coming back down. A floor covering goes on after that, not before.

The commissioning notice itself is a building control matter. Approved Document L requires a notice of completion of commissioning to be given to the building control body, within five days in the general case or 30 days where the work is done by a person registered with a competent person scheme, and says that until it receives that notice the body may decide not to issue a completion certificate. That is a real consequence at the point of sale.

A traditional sand and cement or flowing screed over pipe clipped to insulation gives the highest output per square metre and the most even surface temperature, at the cost of height, weight and a long cure. It is slow to respond, which suits continuous running behind a heat pump and suits intermittent use badly. The thickness matters beyond structure: Approved Document L expects heating systems for screed floors greater than 65mm thick to automatically reduce room temperature at night or when the room is unoccupied, precisely because such a floor cannot react quickly.

Low-profile overlay panels take a smaller pipe in a grooved board and add far less height, which is usually the only reason a retrofit is possible at all. They respond faster and give less output per square metre, so the room's heat loss has to be genuinely low for them to carry the whole load. Between joists, with insulation and spreader plates beneath, is the third route on a suspended timber floor, and its performance depends almost entirely on how well the insulation below is fitted.

Whatever the build-up, the floor covering sits on top of the design rather than beside it. A thick underlay, a heavy rug or a covering not approved for use over heating raises the water temperature needed to get the same output, which pushes the system away from the low flow temperature the rest of the design assumed.

A wet floor circuit is buried and effectively maintenance-free; the manifold is not. Once a year it is worth looking at the flow meters to see that each loop still shows roughly the flow it was set to, checking that actuator heads are seated and moving, and confirming the blending valve is still at the commissioned temperature rather than wherever it was left after a repair. Photograph the flow meter settings once, at handover, and the check takes two minutes thereafter.

Water quality applies to the floor circuit as much as to radiators. Approved Document L's commissioning guidance asks that the owner be told the fluids used and their commissioned concentrations, which is the figure a later engineer needs to check inhibitor levels against. On a system shared with radiators, the floor loops are the coolest part of the circuit and therefore where corrosion products tend to settle, which is another argument for a magnetic filter and for emptying it.

The one job that is not routine is finding a leak in a buried pipe. It is rare in a properly pressure-tested installation and it is specialist work when it happens, relying on thermal imaging and the layout drawing. That drawing is the single most valuable piece of paper from the whole installation, and it is the one most often lost.

Price follows the build-up and the disruption far more than the pipe. What moves a quotation is whether the floor is being built new or opened up, how much height is available at doorways, whether insulation has to be added beneath, how many zones and manifolds are needed, whether the heat source can supply the temperature required or needs blending, what happens to kitchen units and skirtings while the work is done, and how long the property is unusable during screed cure and heat-up. A single room off an existing system is often disproportionately expensive for its area.

LokalMatch is only the introduction. Describe the floor once with your postcode — which rooms, what is under the existing floor, what heats the house now and how much height you can give up — and firms that fit underfloor heating in your area reply. Homeowners are never charged; pros pay for the requests they receive. LokalMatch does not do the installation, does not set prices and does not vet, rank or recommend anybody, so ask each firm what their price includes for insulation, commissioning to BS EN 1264-4 and the layout drawing.