Underfloor Insulation

If you live in a home with timber floors, underfloor insulation is a particularly effective way to get on top of winter chills. High quality underfloor insulation not only stops cold draughts from whistling up between floorboards, it also creates a barrier against moisture that will ensure mould can’t take hold beneath carpets during the wet months. Slabs on grade can be insulated by digging around the perimeter and installing foam board. When the building is new construction, then it might be easier to only install the foam board against the exterior of the slab and footing, or under the slab. Slab foundations with interior insulation provide more termite resistance, but some builders in the southeastern United States have even reported termite infestations through foam insulation on contained slabs.

Underfloor insulation is required for in cool climates and often in other climates. Insulate the underside of suspended floors:

• in cool temperate and alpine climates
• in temperate climates in some cases
• in high humid and hot dry climates where air conditioning is used.

Insulate the edge of slabs-on-ground:

• in cool temperate and alpine climates
• in temperate climates where slab heating is used.

Insulate the underside of slabs-on-ground:

• in alpine climates
• where groundwater is present.

Enclosing subfloor spaces in mixed climates may be sufficient to reduce heat transfer.

Having a timber floor insulated professionally, including filling the gaps between the floorboards and around the skirting, depends on the size and shape of the room and the insulation material used, but typically costs around £800. The insulation will make the room feel warmer in the winter and reduce heating bills by as much as £90 per year.

Underfloor insulation is a simple and effective way to keep your home warm and reduce your energy bills. Regardless of whether you have a suspended wooden floor or a concrete floor, improving your undefloor insulation could save you money. You may also be able to get financial help and other support to help you pay to have the insulation installed by a professional. Solid insulation boards, or rolls of mineral fiber similar to those used to insulate lofts can be fitted between the flooring joists. If your floor is above an unheated cellar or basement you will need to fit the insulation tightly between the joists and secure in place with netting if needed. Plasterboard should then be fixed to the ceiling of the basement to provide fire resistance. If a floor is being replaced, this is a perfect opportunity to improve the standard of insulation. In fact, where this is the case, upgrading your floor insulation is required in order to comply with building regulations. Insulation can be added over the existing concrete slab or underneath a new one. Where insulation is placed above the slab, the rooms will warm up more quickly when the heating is switched on. High performance rigid insulation boards are often the best materials to insulate an existing concrete slab floor, as they provide the best thermal performance at any given thickness. Keeping the thickness of your insulation to a minimum will reduce the likelihood of having to make costly alterations to door openings, stairs and other fixtures as a result of the increase in floor heights.