Floors · 5 min read
Microcement and underfloor heating: a perfect partnership
Why microcement is one of the best finishes you can specify over wet or electric underfloor heating — and the commissioning details that protect it for the long term.
By Jonathan Heywood · 20 June 2025
If you are installing or already have underfloor heating, microcement is one of the best surface finishes you can specify on top. At 2–3 mm total build-up over a screed it has almost no thermal mass to fight through; the floor warms quickly, holds heat evenly, and the seamless surface means no joint expansion to manage.
Compatible systems
- Wet underfloor heating in cement or anhydrite screed — the most common Cornish new-build and barn-conversion specification. Perfect.
- Electric mat systems over a self-levelling compound on plywood or concrete — also fine, provided the compound is at least 6 mm above the mat.
- Loose-laid foil systems directly under engineered flooring — not suitable. The microcement needs a solid, bonded substrate beneath it.
Commissioning protocol
This is the single most important detail. The heating must be commissioned (gradually ramped up and held) before the microcement goes down, then brought up again gradually after cure. Skipping this risks the screed shrinking under the new microcement and cracking it.
- Screed laid and cured per manufacturer instructions (typically 7 days per cm of thickness for cement screed; 2 days per cm for anhydrite).
- Heating commissioned: start at 25 °C, raise by 5 °C every day to maximum operating temperature, hold for 3 days, ramp back down.
- Anhydrite screeds: mechanically sand off the laitance before priming. Critical step.
- Microcement installed.
- After full cure (28 days), bring the heating back up at 5 °C/day.
Running temperature
Microcement is happy up to a surface temperature of 28 °C — comfortably above any sensible UFH operating range.
The bonus
Because microcement is mineral, dense and continuous, it transmits and radiates heat exceptionally evenly. Clients regularly tell us the floor feels warmer than the same heating system felt under their previous timber or tile.
Planning a new heating system or a renovation in Cornwall? Book a site visit — we coordinate with your heating engineer at every stage.