Ground Floor Timber Joists

This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction.

Ground floor timber joists.

Building a wooden floor on top of a dirt floor will lead to eventual rotting of even treated wood though the barrier will delay the onset of this for several years depending on the environmental conditions of the building region. Timber floor joists shall be adequate for the spans and loads and be correctly installed. Solid timber joist sizes are provided in the bs 8103 3 span tables. The following table gives details of allowable spans and spacing between joists for the most common timber sizes used in floor construction.

The ends of these timber joists are built into or suspended by joist hangers from the external walls of the property. Joists left out of an area form an opening called a well as in a stairwell or chimney well. The span table for a 30 psf live load 10psf dead load floor indicates a required fb value of 1 315 and a minimum e value of 1 800 000. True floor joist span calculations can only be made by a structural engineer or contractor.

Hollow floors also known as suspended or timber floors are simply timber joists suspended across and supported by load bearing walls under the floor. Ground floor hollow or timber floor. Creating a vapor barrier only delays the effects of moisture on the wood of the floor. Wood and similar structural floor materials timber floorboards.

In this case your joists are adequate to support a 30 psf live load and 10 psf dead load. 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. In the example the joists have a spacing of 16 inches and a span of 11 feet 2 inches. Joists on the ground floor were sometimes a pole pole joist half round joist log joist.

Wood may be sustainably sourced but a lot isn t. When choosing a timber structural floor layer and timber joists and bearers as well it s important to consider the source of the timber.