Retrofitting heated floors in Harpenden houses
A retrofit is a tight squeeze. The existing floor finish comes up, then any old screed if it is failing, and the new build-up of insulation, pipes and screed has to fit in the depth that is left. Every extra millimetre raises the floor against doors, skirting and the next room.
Liquid screed helps most here. The minimum it wants over the pipes is 25mm, so most floors come out at about 45 to 50mm. Sand and cement has to have roughly 45mm over the pipes, which makes for a noticeably deeper floor. Semis make up 28% of Harpenden's homes, and in a semi being retrofitted that difference can decide whether the doors need trimming.
Being liquid, it surrounds every pipe completely, so no air gaps hold back the heat. It sets flat enough for tiles, LVT and engineered wood, which are the finishes most people want over heating. Faster warm-up and better heating efficiency follow from that close contact with the pipes.
On pour day we first make sure the insulation is butted tight, the membrane sealed and an edge strip fitted to every wall, giving the screed room to expand as it heats up. If any part of that is ours to supply, it is in the written price. Over heating pipes, a pumped screed costs £20 to £35 per square metre on trade2base's June 2026 figures.
Heat-up schedules for Harpenden extensions
New heated extensions have more room to work with, because the floor level is set during the build. That lets the choice between liquid and sand and cement screed follow the finish and the programme rather than the depth.
Whichever is laid, the heating waits. Calcium sulphate is normally ready for heat about 7 days after the pour; sand and cement must sit for 21 days or longer first. Then the system is commissioned gradually: a low flow temperature at first, raised a little each day to the working level. Rushing this is the usual cause of cracks in a heated screed.
We leave the heat-up schedule in writing for you and your heating engineer. With only 11% of Harpenden's homes built since 2000, heated floors here are mostly being added to existing houses, so that schedule is often followed while people are living around the work.
For the material side of calcium sulphate over heating, see our anhydrite screed guide, and about 6.5 miles away, underfloor heating screed in Welwyn Garden City.
Underfloor Heating Screed prices in Harpenden
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 Harpenden
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 Harpenden
Harpenden is about 23.2 miles north-north-east of our Slough base as the crow flies, with postcodes including AL5 and AL3. The nearest towns to it are St Albans (4.5 miles), Luton (5.1 miles), Welwyn Garden City (6.5 miles) and Hemel Hempstead (6.6 miles).
More on underfloor heating screed, part of our screeding services.