Floor or ground insulation: which suits your crawl space?

The difference is in what you insulate. With floor insulation the material goes against the underside of the ground floor — you insulate the floor itself, giving the most direct warm-feet effect. With ground insulation an insulating layer goes on the crawl-space floor — you insulate the space beneath, and that layer also slows the rising damp.

The crawl space often points to the measure. If the space is high enough to work in and dry, the crew can fit floor insulation against the underside — expect € 1,200 to € 2,800. If the crawl space is low, partly filled or damp, ground insulation is the practical choice: the material is blown or poured in and fits even where you can barely crawl. At € 800 to € 1,800 it is also the cheapest measure; the bands per job are in the price index.

The floor type matters for floor insulation. A wooden ground floor is often insulated with wool or foam between the joists; a concrete floor with boards or sprayed foam against the underside. Don't know what you have? The installer determines it on site — just state what you do know about the crawl space in your request.

If damp is in play, the order reverses: cause first, insulation second. Standing water or a wet floor should be assessed with a crawl-space inspection before any layer goes in. Combining can pay off: companies gladly take floor and ground in one job, since the crew is there with its equipment anyway. Cavity-wall, roof and glass insulation are separate trades you place with specialised companies.