Timber Floor Joist Construction

C24 and i joists 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.

Timber floor joist construction. Some newer homes have manufactured i beam shaped joists. The floor joist spacing is the distance between the centers of any two installed joists. Saint gobain building distribution limited trading as jewson registered in england company registration no. The following table gives details of allowable spans and spacing between joists for the most common timber sizes used in floor construction.

Building control may ask for additional engineer s calculations. Putting all these factors together gives the minimum size joists needed for various types of wood grades of lumber sizes of boards spacing of joists and the load that will be placed on the floor. Mouldings planed timber planed timber mouldings skirting cladding wood flooring window boards. Solid timber joist sizes are provided in the bs 8103 3 span tables.

Span the timber specific to the spacing and span that the joist needs to cover is determined in this floor joist spans table. True floor joist span calculations can only be made by a structural engineer or contractor. Since the example house we are designing for is 12 feet wide we need to find in the floor joist span table a joist size and centering that can span 12 or wider. See the image below for an example of joists spaced 16 on center 16 o c.

Floor joist span tables for surveyors floor construction. Note that specific calculations are likely to be required for openings through the floor such as staircases although in practice this is often a doubling up of joists. Apa performance rated i joists pris are manufactured in accordance with pri 400 performance standard for apa ews i joists form x720 this performance standard provides an easy to use table of allowable spans for applications in residential floor construction allowing designers and builders to select and use i joists from various member manufacturers using just one set of span. A floor s framework is made up mostly of wooden joists that run parallel to one another at regular intervals.

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. 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. Timber floor joists shall be adequate for the spans and loads and be correctly installed. 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.

You should also check your local building codes before starting construction and consult a structural engineer in unusual or extreme situations.