Fixing a cold floor: what your floor type tells you about the fix

A cold floor is not a standalone problem but a consequence of how your ground floor is built. Whether it's timber on joists, a concrete slab or a floating screed, where the cold comes from — and what helps — differs. So start with the question of what kind of floor is under your feet; that steers the measure more than the number on the thermostat. The bands per job are in the price index; this piece is about which measure suits which floor.

A wooden ground floor on joists is the classic cold floor. Beneath the boards sits a crawl space that follows the outdoor temperature, and cold air can come along between the boards and past the skirting. For this type, having your floor insulated often pays off quickest: insulation between or against the joists on the underside, where you feel the effect right under your feet. Reckon on € 1,200 to € 2,800, depending on the surface and how well the crew reaches the joists.

A concrete or masonry ground floor feels cold differently: no gaps between boards, but a solid slab that conducts the cold from the crawl space and warms slowly. Insulation against the underside is possible here too, provided the crawl space is high and dry enough to work in. If that space is low or damp, ground insulation is the practical route — an insulating layer on the crawl-space floor that dampens the cold below and slows the rising damp, from € 800 to € 1,800.

That leaves a floor with no crawl space beneath it — a floating screed, or a floor above a garage or another unheated space — where the approach changes, because there is nothing to insulate from a crawl space; that calls for a tailored solution from the installer. If damp, water or a musty smell rises from below, have it assessed first with a crawl-space inspection before any insulation goes in — a wet base is not solved by a layer on top. State in your request what you know about your floor: timber, concrete or floating, and what you see under the hatch.