Span tables for solid timber joists.
Roof joist span tables uk.
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.
Span tables can be used to determine the size of a timber member of a particular strength class required for a given span.
Surveyors span tables for designing roof rafters.
Joist spans over 4 5m provide 2 rows of strutting at third span positions.
Solid timber joist sizes are provided in the bs 8103 3 span tables.
They also tell you what the maximum spacing should be between each section or timber member.
Click on a span to generate a full calculation you can adjust the exact span.
Size of joists mm clear span c16 joist m clear span c24 joist m 47 x 95 47 x 120 47 x 145 47 x 170 47 x 195 47 x 220 1 77 2 40 2 89 3 38 3 87 4 36 2 05 2 67 3 22 3 77 4 31 4 85 assumptions at 400mm centers.
If your old joists do not meet the requirements set by the table they are either supported.
Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings.
Joist spans up to 2 5m no strutting required.
This is the distance between joist centres.
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.
This should be compared to the table.
Solid timber strutting to be at least 38mm thick and be a minimum of three quarters of the joist depth.
Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.
Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.
Permissible clear spans for flat roof joists to bs 5268 7 2 find the column for your dead load and spacing and the row for your timber size to find the permissible clear span in metres.
Usually 400 450 or 600mm but any value can be used up to 610mm max usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size.
This span table is to the format and methodology given in bs 5268 7 2.
Timber floor joists shall be adequate for the spans and loads and be correctly installed.
Floor joist span tables for surveyors floor construction.
