Most lists of underfloor heating supplies name four or five items and stop, which is how installations end up short on the day. A wet system needs around a dozen distinct items before anyone turns a tap, and several of them are the sort of thing nobody thinks about until the screed lorry is booked.
This page is a complete bill of materials for both system types, with what each item is for and why the specification matters. It also does something most supplier pages avoid: it states clearly which items come from a component manufacturer and which you will be sourcing locally regardless of who you buy the components from. We make a lot of this list. We do not make all of it, and pretending otherwise leaves you short.
First, which system you are building, because the two lists barely overlap.
Wet or Electric: Decide Before You Order Anything
Wet, or hydronic, systems circulate warm water through pipe embedded in screed, fed from a manifold connected to a boiler or heat pump. Higher installation cost, much lower running cost, and the right answer for whole houses, new builds and anywhere the heating is the primary heat source.
Electric systems use a resistance cable or mat in the floor build-up, controlled by a thermostat with a floor probe. Cheaper and thinner to install, substantially more expensive to run because you are paying for electricity at full price rather than moving heat. Suits single rooms, bathrooms, retrofits over existing floors, and anywhere running a water circuit is impractical.
The decision drives everything downstream, and our comparison of electric and hydronic underfloor heating covers the trade-offs properly. Cost context for the wet route is in wet underfloor heating cost and installation considerations and what drives installation cost.
Supplies for a Wet System: the Full List
Working from the floor up, then outward to the controls.
Below the Pipe
Insulation boards. Not optional. Without insulation under the pipe a meaningful share of your output heats the ground or the ceiling below. Ground floors need more than intermediate floors, since below an intermediate floor is another heated space. See insulation boards for underfloor heating and types of floor insulation.
Perimeter or edge insulation strip. The item most often forgotten, and the one whose absence cracks floors. A compressible foam strip run vertically against every wall before the pour, continuous with no gaps, standing proud of the finished screed level so it can be trimmed flush afterwards. A screed with nowhere to expand pushes against the wall and cracks. See underfloor heating expansion joints.
A damp proof membrane where the construction requires one.
The Pipe
Floor heating pipe, and here the specification that matters is not the one usually quoted.
You will see pipe advertised as withstanding 95 °C. That is a class rating under EN ISO 15875 for crosslinked polyethylene or EN ISO 22391 for raised temperature polyethylene, and it describes continuous operating conditions against a 50-year design life. It is also irrelevant to your installation, because an underfloor heating circuit runs at 35 °C to 45 °C, nowhere near the envelope.
What actually decides whether the system is healthy in year ten is the oxygen barrier. Pipe without an EVOH barrier to DIN 4726 lets oxygen diffuse straight through the wall into the system water. That oxygen produces magnetite, the black iron oxide sludge that restricts flow, coats heat exchanger surfaces, blocks valve seats and wears pump bearings. Every recurring fault we see on older systems traces back to it.
Specify the barrier, in writing, by standard. The price difference at installation is trivial against a power flush ten years later. Our floor heating pipe carries an EVOH barrier to DIN 4726 in 16 mm, 17 mm and 20 mm.
How much pipe: floor area divided by pipe spacing in metres. At 150 mm centres that is 6.7 m per square metre, at 100 mm it is 10 m, at 200 mm it is 5 m. Add the run from the manifold to each room and back. See underfloor heating pipe layout for the spacing decision.
Fixing the Pipe Down
One of four methods, and the choice affects how consistently your spacing holds:
- Staples or tackers into EPS insulation. Fast, but spacing depends entirely on the installer’s eye.
- Clip rail fixed to the substrate with pipe clipped in at marked intervals. Spacing is repeatable.
- Cable ties to steel mesh. Secure, and the mesh grid gives a spacing reference.
- Castellated or studded panel. Pipe pushed between moulded studs, so spacing is fixed mechanically. The most consistent, and worth the premium precisely because spacing is what determines whether the floor feels even.
The Manifold Assembly
The manifold is the distribution and control centre: a flow bar feeding each loop and a return bar collecting from them, with integral flow meters for balancing and valve inserts for the actuators.
Size it by circuit count, not by room count. A 100 m loop of 16 mm pipe covers about 15 m² at 150 mm centres, so a large open-plan room needs several circuits, and bay layout for movement joints adds more. Our manifold range runs 2 to 13 circuits on 50 mm centres with G3/4″ eurocone connections, in stainless steel and brass. The dimensional and material figures are in our manifold specifications.
A mixing or blending valve where the primary circuit runs hotter than the floor can take. A boiler supplies 60 °C to 80 °C water; a screed floor must not see it. Not needed where a heat pump is already producing 35 °C, since there is nothing left to blend. See underfloor heating mixing valves.
A circulator for the floor circuit, separate from the primary. Duty is the sum of the loop flows; head is usually modest, around 2 m for a domestic manifold, so a standard Class A wet rotor pump is ample. Run it in proportional pressure mode at a low setting rather than on maximum fixed speed.
A manifold cabinet, recessed or surface, sized for the circuit count plus the pump and blending group. Allow roughly 60 mm of width per circuit plus an end allowance.
Insulation shells and flow and return thermometers, usually supplied with the manifold.
The Controls
Thermal actuators, one per circuit, sitting on the valve inserts and driven by the room thermostats. Normally closed is correct for almost all heating work, so a power failure stops heat rather than leaving a floor heating uncontrolled. Driven by a wax thermostatic element, which is why they take three to five minutes to travel. See thermal actuators.
Room thermostats, one per zone. Check the electrical arrangement matches the wiring centre: volt-free, switched live or 24 V are not interchangeable. Where the floor covering has a surface temperature limit, specify a model that takes a floor sensor. See room thermostats, underfloor heating sensors and thermostat types and failures.
A wiring centre or base station. The item most often left off a materials list, and the one whose omission produces the strangest faults. It terminates each zone, supplies the actuator voltage, and provides the volt-free end switch that tells the boiler or heat pump to fire. Without that end switch connected, the heat source either runs permanently or never fires at all, while everything in the cabinet tests perfectly. See base stations.
Screed and Finish
Screed, cement and sand or calcium sulphate flowing anhydrite. The choice changes the bay sizes you are allowed and the curing time before first heat, so settle it before setting out movement joints.
Floor covering, and a specification note worth knowing before you choose: EN 1264 assumes a covering thermal resistance of no more than 0.15 m²K/W. Tile and stone are negligible, vinyl low, engineered wood moderate, and carpet with a thick underlay frequently over the limit on its own. A covering above that figure leaves a correctly designed floor unable to reach setpoint.
System Water
Corrosion inhibitor, and a magnetic filter on the return. Two cheap items that prevent the magnetite problem, and the pair most often skipped. If you specified oxygen barrier pipe, these finish the job.
Tools for a Wet Installation
- Pipe uncoiler or decoiler. Not glamorous, but laying 500 m of pipe off a loose coil is a two-person fight.
- Pipe cutter, for a square cut without deforming the bore.
- Tacker or stapler, or clip rail and fixings, depending on the method.
- Pipe re-rounding tool, to restore a true circle at the cut end so the compression fitting seats properly.
- Pressure test pump with gauge. Essential rather than optional, covered below.
- Tape measure and chalk line, for setting out spacing and bay boundaries.
- Adjustable spanners for the eurocone compression fittings.
- Thermometer, for commissioning and for checking the manifold differential afterwards.
Our general overview of HVAC tools and equipment covers the wider kit.
Supplies for an Electric System
A shorter list, and a different set of concerns.
- Heating cable or mat, sized by area and by the output the room needs. Mats suit regular rectangular areas; loose cable suits awkward shapes.
- Insulation boards, for the same reason as a wet system.
- A thermostat with a floor probe. The probe is not optional on electric systems, because the cable can take the floor surface past the covering’s limit without an air sensor noticing.
- Spare floor probe, or a conduit for the probe so it can be replaced. A failed probe buried in adhesive with no conduit means opening the floor.
- Flexible tile adhesive and levelling compound rated for underfloor heating.
- Conduit, junction box and cable gland for the cold tail and the probe.
- An RCD-protected circuit, designed by whoever is doing the electrical work.
The Load Capacity Question, Answered Correctly
Check the total load of the heating circuit against two things: the capacity of the circuit feeding it, and the switching rating of the thermostat.
If the heating load exceeds the thermostat’s switching rating, the answer is a contactor or relay driven by the thermostat. The thermostat then switches a coil drawing milliamps, and the contactor switches the actual load. It is a standard arrangement and it costs very little.
What you must not do is fit a snubber in the hope of handling the excess. A snubber is an RC network for suppressing voltage transients across a switching contact. It does nothing whatsoever about excess current, and a thermostat switching a load beyond its contact rating will overheat. If anyone suggests that, they have confused two unrelated components.
The Test That Actually Matters on Electric Systems
This is the most important paragraph in the electric section and it is missing from most guidance.
Measure insulation resistance and continuity with a megohmmeter, and record the readings, at three points:
- On delivery, before anything is installed, to prove the cable arrived sound.
- After fixing the cable, before the adhesive or screed goes over it.
- After the floor covering is down, before first energising.
Compare each reading against the manufacturer’s stated values. A drop between readings tells you exactly which stage damaged the cable, while there is still a chance of doing something about it.
This record is also the only evidence that exists if a claim arises later. A cable is the heating element, so unlike a water loop it cannot be bypassed or rerouted; a fault means opening the floor. Nobody will accept a claim without the readings.
Bringing an Electric Floor Up to Temperature
Let the adhesive or levelling compound cure fully first, to the manufacturer’s stated time. Then bring the floor up gradually rather than straight to setpoint: raising the target by no more than about 2 °C every 24 hours is a sensible approach, and it avoids stressing a fresh adhesive bed and a new tile joint.
Respect the covering’s surface limit. Timber and vinyl are commonly capped around 27 °C, and the floor probe is what enforces it.
Commissioning a Wet System
Different sequence entirely, and compressing it is how correctly built floors crack.
Pressure test before the pour. Typically 6 bar held for 24 hours, checking for any drop. Then keep the circuits pressurised through the screed pour, so damage caused by screeding shows immediately rather than in year three.
Photograph every loop before it disappears. Costs nothing, and it is the most valuable document the building will ever have. Anyone who later needs to drill the floor or trace a leak will need it.
Wait out the cure. A cement and sand screed should not be heated for at least 21 days after laying. An anhydrite screed, at least 7 days, subject to the manufacturer’s figure.
Then the heat-up curve: water in at no more than 25 °C for at least three days, then raised to the maximum design flow temperature for a further four days, then cooled down but not below 15 °C before the floor covering goes on. Record the dates and temperatures, because many covering manufacturers require that evidence before honouring a warranty.
Then balance. Set each flow meter to its calculated flow rate with the longest, most resistant loop left fully open. Purge loop by loop if any circuit reads low or unsteady, since air blocks circulation as effectively as a closed valve. See how to bleed underfloor heating.
Then set the controls, and prove one zone can run while the others stay shut. That is what demonstrates the zoning actually works, and it catches actuators left in their first-open position, which is a surprisingly common handover fault.
What We Supply, and What We Do Not
Worth being plain about, because a materials list is only useful if you know where each item comes from.
We manufacture: manifolds in stainless steel and brass with integral flow meters, thermal actuators and the wax elements inside them, room thermostats and wiring centres, oxygen barrier floor heating pipe to DIN 4726, and the mixing valves and other HVAC valves the system needs.
We do not manufacture: electric heating cable or mats, insulation boards, screed, tile adhesive, or the installation tools. Those come from other suppliers, usually local ones, and that is true whoever you buy your components from. An electric system in particular is outside our range apart from the control side.
Saying so is more useful than claiming to supply everything, because a list that quietly omits what the supplier cannot provide is how an installer discovers a gap on the day of the pour.
For distributors and installers stocking components, or brands specifying to their own range, our OEM and ODM service covers configuration, material specification, packaging and market documentation. Tell us the destination market alongside the specification.
Background on the system as a whole is in how underfloor heating works and installation types and methods.
Frequently Asked Questions
What supplies do I need for a wet underfloor heating system?
Insulation boards, perimeter edge strip, oxygen barrier pipe, a fixing method, a manifold with flow meters, thermal actuators, room thermostats, a wiring centre, a mixing valve where the primary runs hot, a circulator, a cabinet, screed, corrosion inhibitor and a magnetic filter. Plus the pressure test pump and laying tools.
How much pipe do I need?
Floor area divided by spacing in metres: 10 m per m² at 100 mm centres, 6.7 m at 150 mm, 5 m at 200 mm. Add the run from the manifold to each room and back for every loop.
What pipe specification actually matters for underfloor heating?
The oxygen barrier, to DIN 4726 with an EVOH layer. The 95 °C class rating you often see quoted is true but irrelevant, since a floor circuit runs at 35 to 45 °C. Pipe without a barrier admits oxygen through the wall and produces magnetite sludge that blocks valves and wears pumps.
What if the heating load is more than my thermostat can switch?
Fit a contactor or relay driven by the thermostat, so the thermostat switches a coil and the contactor switches the load. Do not fit a snubber for this: a snubber suppresses voltage transients and does nothing about excess current, leaving the thermostat switching beyond its contact rating.
How do I test an electric underfloor heating system before the floor goes down?
Measure insulation resistance and continuity with a megohmmeter and record the readings on delivery, after fixing the cable, and after the floor covering is laid, comparing each against the manufacturer’s values. A drop between readings identifies which stage damaged the cable, and the record is the only evidence available if a claim arises.
How long before I can turn on a wet system?
At least 21 days after a cement and sand screed is laid, or 7 days for anhydrite subject to the manufacturer’s figure. Then water at no more than 25 °C for three days, raised to maximum design flow temperature for four days, then cooled to not below 15 °C before laying the covering.
Is perimeter edge strip really necessary?
Yes, and it is the item most often forgotten. A heated screed expands, and with no compressible strip against the walls it pushes against them and cracks. The strip must run continuously with no gaps and stand above the finished screed level so it can be trimmed flush.
Can I put carpet over underfloor heating?
Only with care. EN 1264 assumes a floor covering thermal resistance of no more than 0.15 m²K/W, and carpet with a thick underlay often exceeds that on its own, leaving a correctly designed floor unable to reach setpoint. Decide the covering before finalising pipe spacing.
Reviewed by Maggie Shen, Director at Legom, on October 24, 2026. This article was reviewed for technical accuracy, including the correct use of a contactor rather than a snubber where heating load exceeds a thermostat’s switching rating, the insulation resistance and continuity test regime for electric systems, the EN 1264-4 curing and heat-up sequence for wet systems, the DIN 4726 oxygen barrier requirement and why the 95 °C class rating is not the governing specification, the 0.15 m²K/W floor covering resistance ceiling, and the role of the perimeter edge strip and the wiring centre end switch.