Underfloor heating

Wet underfloor heating runs warm water through pipe loops laid across the floor, so the floor itself becomes the emitter rather than a radiator on the wall. It suits an extension, a kitchen or bathroom taken back to the slab, or a whole ground floor during a renovation. We set out the loops, fit the manifold and commission the system, blended down from your existing boiler.

Screed and low-profile build-ups

The usual build-up is pipe clipped down over insulation and buried in screed. The screed holds the heat and gives it back slowly, so the floor temperature stays even and the room does not swing about with the weather. It needs depth, and it needs curing and drying time before any heat goes through it, which is why it belongs in a new slab or an extension rather than a floor you are patching.

Where the height is not there to give away, we use a low-profile or floating build-up instead. Grooved panels or aluminium spreader plates carry the pipe within a much shallower layer, either over an existing slab or between joists upstairs. It responds faster than screed and eats less headroom, though it stores less heat, so the controls end up doing more of the work.

Under either build-up, the insulation underneath matters as much as the pipe. Without a proper layer beneath the loops, a good part of what you pay for goes downwards into the ground or the ceiling below. We also run an edge strip around the perimeter so the screed can move without cracking against the walls.

Manifolds, zones and flow temperature

Every loop starts and finishes at a manifold, usually tucked into a cupboard or a utility. Each circuit has its own flow meter for balancing and its own actuator, so a room thermostat can shut that zone down without affecting the rest. We keep loop lengths reasonably even, because a long loop and a short one on the same manifold will never balance properly.

Underfloor heating runs cooler than radiators. A large warm surface at a low temperature does the same job as a small hot one, which is why the water going into the floor is blended down rather than sent straight off the boiler. That low flow temperature is also what makes it a natural fit for a heat pump, which loses efficiency the hotter you ask it to run.

Because the floor is slow to heat and slow to cool, it is controlled differently from radiators. Steady running with a modest setback overnight works better than switching it off and expecting it back in half an hour. We set the controls up that way at handover and explain why they are set as they are.

Floor coverings and commissioning

The covering decides how much heat actually reaches the room. Tile and stone conduct well and are the easiest choice; engineered timber is fine where the manufacturer allows it over underfloor heating and the screed has been properly dried first. Solid timber can move, and a thick carpet with a thick underlay insulates the floor from the room, so the combined tog rating needs checking before you buy it.

Before any screed is poured, the loops go on test and stay under pressure while the pour goes down, so if a screeding trowel finds a pipe we know about it that day rather than months later. Once the screed has dried, commissioning brings the flow temperature up in stages, then each loop is balanced at the manifold and the controls are set.

What you are left with is a floor that has been tested, a manifold that is labelled, and a layout drawing showing which loop feeds which room. Keep that drawing. It is what tells anyone lifting a floorboard or drilling a fixing where the pipe actually runs.