Suspended Timber Ground Floor Joists

Different types of ground floor suspended flooring.

Suspended timber ground floor joists.

Suspended timber floors need to have spaces underneath ventilated via air bricks through the outer walls and gaps in any internal walls so that the air can move across the building underneath the floors to prevent the build up of moisture in the timber which could lead to fungal attack. At the turn of the 18th century when construction techniques moved from boarded floors installed directly on the ground to suspended timber floors over a ventilated chamber the innovation solved a significant problem. Solid floors are a lot more substantial and require the ground to be made up in layers of ground sub base sand compacted hard core damp proof membrane insulation and concrete. Suspended timber floors which are typically found in older houses are normally made from timber floorboards which are then attached to joists just above the foundations of a house.

This creates a small gap and allows ventilation and air movement to prevent damp forming in the timber joists. These floor joists are raised above the subfloor on small supporting walls called tassel walls or sleeper walls. This floor insulation method is commonly used for upgrading the thermal performance of existing timber floors as it has no impact on floor levels. The floor can be formed in various ways using timber joists precast concrete panels block and beam system or cast in situ with reinforced concrete.

A suspended floor is a ground floor with a void underneath the structure. Previously floor timbers had been prone to damp and rot thanks to their direct contact with the moist ground. They can normally span greater distances than timber joists. These can be classed as either suspended or solid.

The simplest way of insulating suspended timber ground floors is to fit insulation boards between the joists and support battens. If the ground floor in question is of a suspended timber construction and whether this is a renovation or new build project then the insulation would normally be installed in the joist zone that is installed between the joists. There are 2 types of floor construction used in the building industry today. Concrete vs timber floors.

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. Ground floor hollow or timber floor. The ends of these timber joists are built into or suspended by joist hangers from the external walls of the property. Hollow floors also known as suspended or timber floors are simply timber joists suspended across and supported by load bearing walls under the floor.