Heated extensions on Barnet's inter-war semis
Barnet's eastern half grew up around the High Barnet branch of the Northern line, its western half around the Edgware branch, and inter-war semis line both. Extend one of those houses at the back and the new space nearly always becomes a kitchen and family room, where underfloor heating appeals because no radiators take up the walls.
How well those pipes warm the room comes down to the screed laid over them. It carries warmth out from the pipes and shields them, so the depth over the pipes is not something to shave. Liquid screed wants 25mm over the pipes at the least, about 45mm to 50mm overall, and sand and cement wants about 45mm of cover. Every pipe has to be wrapped completely with no pockets of air, one reason a flowing mix is a popular choice over heating; Barnet liquid screed explains how it goes in.
What sits beneath is just as important. Insulation sends the heat upwards instead of into the ground, edge strip gives the screed room to expand against the walls, and a membrane keeps screed and insulation apart. We look over that build-up before any pour, and we can supply and lay it too, through our insulation and membrane work.
In an older house, the limit is usually height. The new heated floor must meet the old house level at the kitchen doorway, so the insulation, pipe and screed depths are all worked back from that finished level before anything gets ordered.
Switching the heating on in a Barnet extension
Cranking the heating up the day after a pour is a reliable way to crack new screed. Bringing it into use has to be gentle: a low flow temperature first, then small rises spread over a number of days.
The material sets the start date. With calcium sulphate, the heating can usually run from about 7 days, and running it helps the floor dry. Cement screed is different: give it 21 days at the very least before the heating comes on. You get a written heat-up schedule for the screed you have, so your heating engineer and your flooring fitter are reading from one plan.
Your heating installer should lay, clip and pressure test the pipes before we turn up, and the extension needs to be keeping the weather out. When we arrive to pour, we go over the clips and the edge strip, then lay the screed.
The finish depends on a flat base. LVT, tiles or engineered boards over warm pipes all need one, and the screed thickness guide explains the depths involved. £20 to £35 per m² is the 2026 UK price band for a pumped screed over heating pipes. If you are just across the northern boundary, see heated floor screeding in Enfield.
Underfloor Heating Screed prices in Barnet
Liquid screed over underfloor heating: £20 to £35 per m² supplied and laid (trade2base, June 2026), so £700 to £1,230 for 35 m². trade2base gives these figures excluding VAT. See our floor screeding cost guide or screed calculator.
Who lays your underfloor heating screed in Barnet
K & B Screeding’s own team, led by director Donatas Bardisevicius. Founded 2019, company 12298780.
See what customers say in our Google reviews and on our testimonials page.
Underfloor Heating Screed from Slough to Barnet
Barnet is about 19.9 miles east-north-east of our Slough base as the crow flies, with postcodes including EN5, N11, HA8 and NW11. The nearest towns to it are Haringey (4 miles), Borehamwood (4.4 miles), Brent (4.7 miles) and Camden (5.2 miles).
More on underfloor heating screed, part of our screeding services.