True floor joist span calculations can only be made by a structural engineer or contractor.
Floor joist wood beam span table.
Floor joist span tables for surveyors floor construction.
This should be compared to the table.
Span calculator for wood joists and rafters also available for the android os.
Other span tables are based on the guidance given in bs 5268 7 1 which is a uniformly distributed load of 1 5kn m for spans greater than 2400 mm and 3 6 kn load per metre width of floor for spans less than 2400 mm to ensure that very small joist sizes do not result from the calculations for smaller spans.
Also available for the android os.
Our floor joist span tables are based on loadings given in the newer amended version of bs 6399 1.
So the house dimensions will now be 24 x 13.
This means that some values are slightly more conservative than span tables from other sources if those do not include the amended guidance.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
Beam and joist span tables built up wood floor beams supporting one floor in a house maximum spans for uniformly distributed loads species and grade supported built up beam size joist length 3 2x8 4 2x8 3 2x10 4 2x10 3 2x12 4 2x12 8 9 8 11 2 11 10 13 8 13 8 15 10 10 8 8 10 0 10 7 12 2 12 3 14 2.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
You need to measure the complete span of your floor joists together with the distance between them the centres and the size of the timbers.
Let s expand our house beyond that 17 2 span capability to 24 feet wide.
Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
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.
Span tables for domestic floor joists to bs 5268 7 1 note.
View joist rafter tables.
The tables permit a bearing length of up to 3 5 inches but since 1 5 is probably the worst case that you ll encounter for joist or rafter bearing it s a safe value.