Underfloor Heating Installation

Neither is better everywhere. They suit different jobs:

There are three main ways to lay the pipes:

• In screed: Insulation boards are laid on the concrete slab, the pipes are clipped on top in loops, and a screed is poured over them. This is the usual method in extensions and new builds. The screed must cure fully before the heating is run, and then it is brought up to temperature gradually.
• Low-profile overlay boards: Grooved boards are laid on an existing floor, and the pipe is pressed into the grooves. They add much less height than screed, so they suit renovations.
• Suspended timber floors: The pipes run between or on top of the joists, with insulation below and aluminium spreader plates to spread the heat.

Each loop of pipe runs back to a manifold, which controls the flow to each one. Each room or area is a zone with its own thermostat, which opens and closes an actuator on the manifold. When the system runs from a boiler, a pump and mixing valve reduce the water to the lower temperature the floor needs. The pipes are pressure-tested before any screed or floor goes down.

For a completely new system, see our central heating installation service, and for the room thermostats, our thermostat and heating control installation service.

Electric systems come as thin mats or cable under tiles or stone, or foil mats under laminate and engineered wood, with insulation boards underneath. Each room has a thermostat with a floor probe.

Electric underfloor heating needs a suitable electrical supply, often a new circuit. That work is carried out through our domestic electrical installation service and certified through one of the routes the building regulations allow. The heating cable is resistance-tested before, during and after the floor is laid.

Yes, in most cases. The question is how much the floor can rise:

• Electric mats under new tiles add very little height, which makes them the usual choice for a bathroom refit.
• Low-profile wet overlay boards add more, so doors, thresholds, skirting and kitchen units may need adjusting.
• Lifting floorboards on a suspended timber floor lets wet pipes run between the joists with little change in height.
• Digging out a solid floor during a major renovation allows a full insulated screed system.

Insulation under the heating is essential. Without it, much of the heat is lost downwards. A new floor in an extension or new build must also meet the insulation standards in the building regulations, which building control checks.

The floor finish affects how well the heat comes through:

• Tiles and stone conduct heat best. We lay them through our installing kitchen and bathroom tiles service.
• Engineered wood and laminate work well if the product is approved for underfloor heating.
• Vinyl and LVT work if the maximum floor temperature set by the manufacturer is respected.
• Carpet works with a low-tog underlay. Typical guidance is a combined tog of no more than 2.5 for the carpet and underlay together.

The best time to fit underfloor heating is when the floor is being built. It is a popular choice for a kitchen extension and other house extensions, for new build homes and basement conversions, and in a bathroom renovation, where it frees up wall space. Because we build the floor as well, everything is laid in the right order.

Wet underfloor heating is usually economical to run. A large heated floor warms the room with water at a lower temperature than radiators need, which suits a condensing boiler from our boiler installation service and especially a heat pump, which runs most efficiently at those temperatures. If you are planning a heat pump, design the underfloor heating in from the start. Electric underfloor heating costs more per unit of heat, because electricity costs more than gas. It is most economical in smaller rooms or for occasional use. In both cases, good insulation and room-by-room thermostats with sensible schedules keep running costs down.