Insulation of Suspended Wooden Floors

suspended wood flooring in the home

Suspended wooden floors are very often forgotten when it comes to insulating a house. People insulate the roof space, double glaze the windows but forget to insulate the floors, but if the rest of the room is insulated, the floor becomes a thermal weak point.

A solid ground floor is difficult to insulate retrospectively. However, if there is enough room to increase the height of a floor slab or if it is a suspended concrete slab construction, one can sometimes get access under the floor making it possible to improve insulation.

Suspended wooden floors can often be insulated and, depending upon the space under the floor, the floorboards may not need to be removed and the job can be carried out within a day.

Timber floors often let drafts in between the floorboards from the underfloor airbrick ventilation that needs to be there to allow the timbers to dry out and to ventilate the under floor cavity.

Such floors can be insulated below the timbers by insulating the space between the joists. This insulation sometimes needs fastening with battens or similar to hold it in place.

Under the joists, a sheeting material such as Airtec, similar to bubble wrap with foil to one or both sides, can be used and simply stapled to the undersides of the joists. This will provide thermal insulation and, as an added bonus, can sometimes remove musty smells where present.

It is important to check that the ends of the joists can breathe if they are set into solid walls without damp proof courses or other protection. Should no access be available to the underfloor void, insulation needs to be applied on top of the floor or by lifting the floorboards and ‘dropping’ (i.e, suspending) the insulation between the joist before relaying the timber floor.

Arguably the least disruptive way to improve the internal environment while occupying a property is to adopt a thermal underlay to a carpet to improve the internal environment. This would be the easiest method of improving the insulation but is less thermally beneficial.

For advice on the application of underfloor insulation, a competent builder would be happy to advise. Some DIY stores and builders’ merchants may also be able to offer advice including Advice Sheets explaining the principles.

For a larger floor, or where the job requires professional input or supervision, do not hesitate to consult your local independent Chartered Surveyor.