Timber Joist Floor Construction

The width of these spans depends on the size of the timber used for the floor joists and more can be seen about joist spans in our loadbearing walls project.

Timber joist floor construction.

Ceiling joists are usually 2 by 6s or sometimes 2 by 4s if it is an older home. The outermost joist in half timber construction may be of a more durable species than the interior joists. Floor joist span tables for surveyors floor construction. Solid timber joist sizes are provided in the bs 8103 3 span tables.

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. The weight of the timber floor itself consists of the timber joists the plasterboard ceiling underneath it except for suspended timber ground floors the floorboards and the nails or screws used to fix both of the aforementioned coverings. Joists and beams are two types of structural elements that have similar and related functions in home construction. Some newer homes have manufactured i beam shaped joists.

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. Section r502 10 of the international residential code states that header joists can be the same size as the floor joists when the header joist span isn t greater than 4 feet but if the header joist span is more than 4 feet you ll need to double the header joist and ensure that it s capable of. Between the joists the area called a joist bay and above the ceiling in some old houses is material called pugging which was used to deaden sound insulate and. Floor joists are typically 2 by 8s 2 by 10s or 2 by 12s.

How to construct a suspended timber floor as we described above the construction is relatively simple to understand which is why this type of floor construction is so popular. Where the tables do not apply or where there are concentrated loads floor joists should be designed by an engineer in accordance with technical requirement r5. Both are horizontal members meaning they are installed level with the ground or floor below and both are supported on their ends and sometimes in their middles by load bearing walls columns or other types of vertical supports. A floor s framework is made up mostly of wooden joists that run parallel to one another at regular intervals.

Timber floor joists shall be adequate for the spans and loads and be correctly installed. The following table gives details of allowable spans and spacing between joists for the most common timber sizes used in floor construction. True floor joist span calculations can only be made by a structural engineer or contractor.