The following table gives details of allowable spans and spacing between joists for the most common timber sizes used in floor construction.
Timber ground floor construction details.
3 16 ground floor timber separating wall.
3 10 ground bearing floor slab.
The ends of these timber joists are built into or suspended by joist hangers from the external walls of the property.
Insulation above slab.
This construction is similar to the timber floor above but uses either pre cast concrete planks or small pre cast concrete beams with concrete blocks laid between the beams.
Government accredited details developed by bre for local government.
Although this method is very labour intensive the cost of materials is relatively low hence the appeal for diyers with access to free labour.
E13 gable insulation at rafter level e3 sill.
Normal spacing is 16 inches on center from center to center though some floors may have joists on 12 inch or 24 inch centers.
Ventilation is required in the same way as a suspended timber floor.
Ce 200 details of construction.
Ground floor hollow or timber floor hollow floors also known as suspended or timber floors are simply timber joists suspended across and supported by load bearing walls under the floor.
E6 intermediate floor within a dwelling.
Floor joists spaced on regular intervals span the areas between supports such as walls foundations girders and beams.
Ground floors built of solid concrete remain popular with small builders and can often be an economic solution for home extensions.
They can normally span greater distances than timber joists.
Suspended timber ground floors consist of the finished timber floorboards being attached to floor joists which are suspended above the subfloor of the foundation.
All the figures are based on normal domestic floor loadings where the floor construction is typically 18 25mm floor boards sheets with up to 12 5mm thick plasterboard and skim underneath.
Construction details construction details.
These floor joists are raised above the subfloor on small supporting walls called tassel walls or sleeper walls.