Draught Proofing Floors, Skirting Boards and Ceilings

Timber ground floors were first raised off the ground in the eighteenth century to prevent the timbers rotting through contact with damp ground. The space beneath the floor is ventilated via airbricks in order to keep moisture levels low but this inevitably means that the floor itself is exposed to the external air, increasing heat losses and creating cold draughts. Cold air comes up through the edges of the floors and under the skirting boards or through the gaps between the floor boards.

If you insulate your ground floor you will dramatically reduce heat losses but it is still important to draught-proof the floor as gaps will remain in the insulation through which cold air can flow, undoing the good work of the insulation. If you lift the floorboards to install the insulation (which is often the most effective way to fit it), you can cover the joists with a breather membrane which will hold the insulation but aldraft-skirting-boardsso act as a draught excluder. It should be taped up behind the skirting boards before they are put back. If you are unable or unwilling to install insulation because of potential damage to your floor boards, draught-proofing is essential to reduce heat losses and draughts.

The intermediate floors of traditional homes in Cheltenham are typically constructed of timber with the joists buried in the solid walls. These floors may also be a source of draughts because the void within the floor is exposed to a thin solid wall with no interior finish, unlike the plasterwork in the rooms themselves which plays an important role in stopping air infiltration. There are typically lots of fine gaps in these walls, especially in the mortar joints, through which cold air can infiltrate the floor void. Consequently draught-proofing of upper floors and the ceilings below them is also worthwhile.

Most of the timber floors of the traditional buildings of Cheltenham were constructed by simply butting the boards up against each other and nailing them to the joists below. The movement of these floorboards over the subsequent decades inevitably opened up the gaps between them, letting the draughts through. However, in some cases, tongue and groove edge joints were used with the nail head hidden within the joint. These floors are less prone to draughts, except at the edges, because of the overlapping joints.

The simplest way to draught-proof a suspended timber floor is to cover the whole thing up with hardboard, insulating underlay and carpet. However you should first draught-strip the junction of the skirting board and the floor using a sealant or plugging it with a compression strip. Similarly, plug the gaps round service pipes such as central heating pipes that pop up through the floors to supply radiators.

If you want to keep your timber floor finish exposed, you also need to plug all the gaps between the floor boards. This can be done in a variety of ways. Holes and gaps should be repaired with small timber patches; smaller holes and cracks can be repaired with proprietary filler or with compression strips designed to be squeezed between the boards. Wide gaps between boards can be repaired with thin strips of softwood glued into the gap.

If cold air is penetrating your upper floor voids or your roof space, it will also find its way through the gaps in ceiling roses and ceiling-recessed lights. These gaps should be sealed as carefully as possible.