Underfloor Heating: Types, Costs and What You Need to Know
Underfloor Heating: Types, Costs and What You Need to Know
Underfloor heating has gone from a luxury feature to a practical choice for many homeowners. It frees up wall space, distributes heat evenly and works efficiently with modern boilers and heat pumps. But it is not right for every situation. This guide covers the two main types, costs, running expenses and the practicalities of installation.
Wet vs Electric Underfloor Heating
There are two fundamentally different systems, and the right choice depends on whether you are building from scratch or retrofitting an existing room.
Wet (Water-Based) Underfloor Heating
A wet system pumps warm water through a network of plastic pipes laid beneath the floor. The pipes are connected to your boiler or heat pump via a manifold that controls the flow to each zone. The water temperature is much lower than in radiators, typically 35 to 50 degrees compared to 60 to 75 degrees, which makes wet underfloor heating particularly efficient.
Best for: Whole-house heating in new builds, extensions and major renovations where the floor is being replaced anyway.
Electric Underfloor Heating
Electric systems use thin heating cables or mats laid directly beneath the floor finish. They are much thinner than wet systems and add minimal height to the floor. Installation is simpler, but running costs are higher because electricity costs more than gas per unit of heat.
Best for: Individual rooms, retrofitting into existing spaces, bathrooms and kitchens where the floor is being tiled.
Installation Costs
Wet Underfloor Heating
Wet underfloor heating costs are calculated per square metre, covering materials (pipes, manifold, insulation, screed) and installation labour. The total installed cost depends on the size of the area and complexity of the layout.
Additional costs to factor in include the manifold and controls, screed if not already planned, connection to your existing boiler and dedicated thermostats for each zone. A detailed quote will break all of these down for your specific installation.
Electric Underfloor Heating
Electric underfloor heating is more affordable to install than wet systems, with costs calculated per square metre for the heating mat or cable kit and installation labour. A small bathroom is one of the most cost-effective rooms to fit with electric underfloor heating, while a larger kitchen will naturally cost more due to the greater area.
Running Costs
This is where the two systems differ significantly.
Wet System Running Costs
A wet underfloor heating system running off a gas boiler costs roughly the same as radiators for the same floor area, and often less because of the lower water temperature required. Annual running costs are comparable to a traditional radiator system for the same floor area.
If connected to a heat pump instead of a gas boiler, the efficiency gains are even greater. Heat pumps operate most efficiently at low flow temperatures, which is exactly what underfloor heating needs.
Electric System Running Costs
Electric underfloor heating costs approximately 3 to 4 times more to run than a wet system for the same area. However, most electric systems are installed in single rooms and used with a thermostat and timer, so the actual annual cost for a single bathroom is very modest.
The key is not to use electric underfloor heating as your primary heat source for a whole house. It works well as supplementary heating in rooms where you want warm feet — bathrooms, en-suites and kitchens.
Best Rooms for Underfloor Heating
Bathrooms and En-Suites
The most popular choice. Warm tiles underfoot are a genuine luxury, and the small area keeps costs manageable. Electric mats are the usual choice here.
Kitchens
Large kitchen floors benefit from the even heat distribution. If the kitchen is being refitted and the floor replaced, it is the ideal time to add underfloor heating.
Open-Plan Living Spaces
Underfloor heating excels in open-plan rooms where radiators would interrupt long wall runs or glass doors. A wet system is the right choice for these larger areas.
Extensions and Conversions
New extensions are the easiest place to install wet underfloor heating because the floor is being built from scratch. Garage conversions and loft conversions can also benefit, though insulation quality is critical in these spaces.
Conservatories
A common application across the Wirral, where many 1930s and 1960s homes have had conservatories added. Underfloor heating keeps a conservatory usable through winter without the need for bulky radiators.
Floor Types and Compatibility
Not all floor finishes work equally well with underfloor heating.
- **Porcelain and ceramic tiles:** Excellent. High thermal conductivity means heat transfers quickly and efficiently. The best choice for bathrooms and kitchens.
- **Natural stone (slate, limestone, marble):** Very good. Similar thermal properties to tiles, though some stones need sealing.
- **Engineered wood:** Good. Engineered boards cope with the temperature changes better than solid wood. Check the manufacturer's maximum surface temperature rating.
- **Solid wood:** Acceptable with caution. Solid timber can dry out and shrink with underfloor heating. Narrow boards cope better than wide planks. A maximum surface temperature of 27 degrees is usually recommended.
- **Laminate:** Good. Most laminates are compatible, but check for a specific underfloor heating suitability rating.
- **Carpet:** Acceptable but reduces efficiency. Carpet and underlay act as insulation, meaning the system works harder to heat the room. If using carpet, choose a low tog rating (under 1.5 tog combined for carpet and underlay).
- **Vinyl and LVT:** Good. Luxury vinyl tiles work well and are a popular combination with underfloor heating in kitchens and bathrooms.
Building Regulations
Underfloor heating installations must comply with Part L (conservation of fuel and power) and Part P (electrical safety, for electric systems) of the Building Regulations.
For wet systems, the floor must be adequately insulated beneath the heating pipes to prevent heat loss downward. This is particularly important on ground floors. The insulation and screed will raise the floor level by 50 to 75mm, which needs to be accounted for at door thresholds and stair connections.
Electric systems installed in bathrooms must comply with the wiring regulations for wet zones. A qualified electrician should carry out or sign off the electrical connections.
Retrofitting vs New Build
New Build or Extension
This is the ideal scenario. The floor structure can be designed around the underfloor heating from the outset. Insulation, pipe layouts and screed depths are all planned in advance. Cost and disruption are minimal because the work is part of the wider build.
Retrofitting Into an Existing Room
Retrofitting is possible but more involved. The existing floor must be lifted, insulation added, pipes or cables laid and a new floor surface installed on top. The main challenge is the increase in floor height, which affects door clearances, stair heights and transitions to adjacent rooms.
Low-profile wet systems are available that add as little as 15 to 20mm to the floor height, but they cost more than standard systems and have slightly lower heat output.
Electric mats add only 3 to 5mm and are the easiest retrofit option, particularly under new tiles.
Is Underfloor Heating Worth It?
For new builds and extensions where the floor is being constructed anyway, wet underfloor heating is almost always worth considering. The additional cost is modest relative to the overall build, and the benefits — even heat, freed wall space and efficient operation with modern heat sources — are significant.
For single rooms in existing homes, electric underfloor heating is a cost-effective upgrade that adds genuine comfort, particularly in bathrooms.
The one scenario where underfloor heating is not worth the investment is retrofitting a wet system into an occupied home with finished floors you want to keep. The disruption and cost of lifting and relaying floors usually outweigh the benefits.