Fitting heated floors into existing Welwyn Garden City houses
Floor height is the constraint on almost every retrofit. With the old floor removed, insulation, pipes and enough screed to cover them all have to fit in the hole, and the result must still meet the retained hallway and thresholds at the same level.
So the type of screed makes a real difference. Liquid needs 25mm minimum over the pipes, which usually lands the floor at 45 to 50mm deep. A sand and cement screed needs about 45mm of cover, so the finished layer is noticeably thicker, and the insulation beneath still has to fit in the same dug-out space. On a tight retrofit that difference often decides whether the heating can go in at all, which is why a thin pumped liquid screed is so often chosen.
Because it flows, liquid screed also closes round every pipe and leaves no trapped air to hold the heat back. The floor warms up faster and heats more evenly, so the room responds sooner when the thermostat calls for heat.
The pipework itself belongs to your heating engineer, who fixes the pipes down and tests them under pressure; we then check the insulation, membrane and edge strip before pouring, and can provide those layers through insulation and membrane supply if they are missing. For the full range of depths by screed type, the screed thickness guide has the figures in one place.
Switching on heated floors in Welwyn Garden City
Switching on for the first time is the risky moment for a heated floor. Turning the system to full on a damp screed can crack it, so the heating is commissioned gradually, starting low and rising a few degrees a day to the working temperature.
Timing depends on the material. Calcium sulphate will usually accept heat from roughly 7 days after pouring. Give a sand and cement floor at least 21 days before any heat goes in. In both cases the heat-up is also what dries the floor for coverings, and we hand over a schedule to follow.
New homes are often designed with heating in the screed from the start, and the specification will state the depth and grade; the homes planned at the Wheat Quarter point to liquid screed on a larger scale. Heated extensions and garden rooms on existing houses are more often a mix of old and new, where the new floor must meet the house and the pipes may join an existing boiler or heat pump.
Either way, tell us the pipe layout and the flooring you plan. Tiles, LVT and engineered wood all sit well on a heated screed laid flat, but each has its own moisture limit before it goes down.
Underfloor Heating Screed prices in Welwyn Garden City
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 Welwyn Garden City
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 Welwyn Garden City
On the map, Welwyn Garden City sits north-east of Slough, about 26.6 miles from our base in a straight line (postcodes including AL8, AL6, AL7 and AL9), next to Hatfield (2.7 miles), Hertford (5.6 miles), Harpenden (6.5 miles) and St Albans (6.7 miles).
More on underfloor heating screed, part of our screeding services.