For new builds, a wet screed underfloor system is still hard to beat on raw efficiency. But ninety percent of the projects we touch in Hilversum, Blaricum and the surrounding region are renovations — and that's where Fermacell's dry underfloor system has quietly become our default.

The product is straightforward: a 25 mm gypsum-fibre element with pre-routed channels for 16 mm PE-RT pipework, dropped over a thin levelling layer. Total build-up sits between 25 and 32 mm depending on the variant. Compare that to the 70–100 mm a traditional cement screed needs and the implications are obvious — you keep ceiling heights, door reveals stay where the architect drew them, and listed-building thresholds remain intact.

What sells it on site is the schedule. A wet screed needs roughly one millimetre per day of curing before you can heat it, and you can't tile or finish floors until the moisture content drops below 1.8 CM%. On a 60 m² floor that's a four-to-six-week pause. With Fermacell Therm, we're walking on the floor the same day it's laid and finishing over it within 48 hours.

The system also pairs cleanly with low-temperature heat sources. Most of our recent installs run a 35 °C flow temperature from a Daikin or Mitsubishi monobloc heat pump — the dry construction reacts quickly because there's no thermal mass fighting the controller, so the room reaches setpoint without the lag a thick screed introduces.

It is not the right answer for every job. Heavy thermal mass still wins for buildings that want to coast on solar gain. But for the projects we see most — well-insulated renovations on first-floor apartments, timber sub-floors, listed properties — Fermacell Therm is the system we trust.