The Importance Of Ventilating Suspended Timber Ground Floor Structures

The "hole" truth about airbricks

One may ask what is the purpose of those perforated bricks or metal plates often seen to the base of external walls to houses and flats?

To some householders, they seem to be responsible for an awful draft in their living room, especially having now removed all the carpets to reveal the wonderful natural appearance of the original floorboards.

The ‘draft’ created by airbricks or other forms of vents is critical in removing damp stagnate air from the void beneath the floor structure.

The fact that you may experience drafts around the perimeter of a room or through those newly varnish exposed floorboards means that the vents are fulfilling their function and reducing the possibility of dry-rot developing in the floor structure.

Technical details and diagramms are included in the Building Regulations Approved Document C, which you can download free from here.

Dampness in a void beneath a suspended timber floor structure is not uncommon in pre-Second World War buildings. The main source is natural ground water beneath the building.

Older properties are unlikely to include damp proof membranes laid over the bare earth or within the thin layer of concrete poured over the original site. As a result, there will be a build-up of damp air unless adequate sub floor ventilation is provided.

The original builders appreciated this issue and this accounts for the vents often seen at opposite ends of the building. Make sure that you do not undo this vital original design feature; do not block these vents with flowerbeds, paving or with solid floors to extensions.

Advising on these features (or lack of them) is standard within a Woodward Chartered Surveyors House Purchase Survey and Building Survey.

Check out our Survey Services by clicking on the links below:

Latest from our blog