Underfloor Heating: Your Complete Guide

Thin heating mats or cables are laid directly onto the subfloor and tiled or floored over. They add just 3-5mm to the floor height, making them perfect for retrofitting into existing rooms without raising door thresholds. Quick and cheap to install, but more expensive to run than wet systems. Best for individual rooms - bathrooms, en-suites, kitchens - rather than whole houses.

Plastic pipes are laid in loops beneath the floor, carrying warm water from your boiler or heat pump. Much cheaper to run than electric, especially with a heat pump where running costs drop to just 2-4p per m² per hour. The main drawback is installation complexity - traditional systems need a 65-75mm screed layer, which makes them best suited to new builds, extensions, or major renovations where floors are being replaced anyway.

Rooms where UFH is less effective

• Bedrooms with thick carpet - heavy underlay and deep-pile carpet insulate the floor, blocking heat from reaching the room
• Rooms above uninsulated spaces - heat loss downwards wastes energy if the floor is not insulated beneath
• Very small rooms with lots of furniture - a radiator may heat the space just as well at a fraction of the cost
• Upstairs rooms in older houses - retrofitting wet systems upstairs often requires structural work to support the weight of screed

Is underfloor heating cheaper to run than radiators?

Wet underfloor heating paired with a modern condensing boiler or heat pump is typically 15-25% cheaper to run than radiators because it operates at lower water temperatures (35-45 degrees C vs 60-70 degrees C for radiators). Electric underfloor heating is more expensive to run than gas central heating, so it works best in small rooms like bathrooms where it supplements the main heating rather than replacing it entirely.

Can you put underfloor heating under any floor?

Most floor types work with underfloor heating, but some are better than others. Stone, tile, and polished concrete are ideal because they conduct heat well. Engineered wood works fine. Solid hardwood is possible but needs careful specification to avoid warping. Thick carpet with heavy underlay acts as insulation and reduces the system's effectiveness - if you want carpet, choose a low-tog rating (under 1.5 tog combined for carpet and underlay).

How long does underfloor heating take to warm up?

Electric underfloor heating warms up in 20-30 minutes, making it responsive enough to switch on and off as needed. Wet systems embedded in screed take 2-4 hours to reach temperature because the thermal mass of the screed needs to heat through first. Low-profile wet systems with aluminium spreader plates heat up faster - usually within an hour. Most people run wet systems on a timer rather than switching them on and off throughout the day.

Does underfloor heating add value to a house?

Underfloor heating is considered a premium feature by estate agents and buyers. It will not add a specific percentage to your home's value, but it can make your property more attractive and easier to sell, particularly in kitchens, bathrooms, and open-plan living spaces. Wet systems connected to a heat pump also improve your EPC rating, which increasingly matters for mortgages and rental regulations.

Can you retrofit underfloor heating without digging up the floor?

Yes. Electric mat systems can be laid directly on top of an existing subfloor and tiled over, adding just 3-5mm to the floor height. Low-profile wet systems use thin aluminium spreader plates that sit on the existing floor, adding around 15-25mm of height. Traditional wet systems with screed require the floor to be dug up or raised by 65-75mm, which is usually only practical during a renovation or new build.