Timber Flat Roof Joist Span Tables

Surveyors span tables for designing roof rafters.

Timber flat roof joist span tables.

Timber floor joists shall be adequate for the spans and loads and be correctly installed. Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12. 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. Timber and concrete upper floors.

Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. Span tables span tables can be used to determine the size of a timber member of a particular strength class required for a given span. 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. For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3.

Other more complex load condition spans can be determined with our free hyne timber design 7 5 software. Flat roof with no permanent access and altitude not exceeding 100m 0 75 kn m udl 0 9 kn point load most areas exceeding 100m but not exceeding 200m excluding parts of scotland pennines north east england refer to bs 6399 3 1 kn m udl 0 9 kn point load. 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. Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

Span tables for flat roof joists to bs 5268 7 2 imposed loads of 0 75 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude does not exceed 100 metres refer to bs 6399 3. Click on a span to generate a full calculation you can adjust the exact span. This span table is to the format and. They also tell you what the maximum spacing should be between each section or timber member 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.

Should refer to trada document span tables for solid timber members in floors ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice. Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs. Solid timber joist sizes are provided in the bs 8103 3 span tables.