Permissible Clear Spans for Ceiling Joists (to BS 5268-7.3)

The allowable clear spans have been calculated in accordance with BS 5268-2:2002 Structural use of timber - Part 2: Code of practice for permissible stress design, materials and workmanship and BS 5268-7.3:1989 Structural use of timber - Section 7.3 Ceiling joists.

The dead loads shown at the top of span table above do not include the self weight of the joists, however, the joist self weights are included (in addition to the dead loads) in the calculations used to determine permissble clear spans.

These span tables do not apply to ties of trussed rafters.

Ceiling joists may be continuous or made up of shorter lengths joined at intermediate supports such as binders.

Holes and notches cannot be drilled or cut into the joists unless proved adequate by specialist calculations.

Timber to be covered, these span tables do not apply to timber which is fully exposed to the elements.

Wane as allowed in BS 4978:2007+A2:2017 is permitted in all sections included in these span tables.

Joists are to have minimum end bearing of 40mm.

These span tables are based on the imposed loads given in BS 5268-7.1 and BS 6399-1, with an imposed uniformly distributed load of 0.25kN/m² acting together with a concentrated (point) load of 0.9 kN.

These span tables make no additional allowance for water tanks or any other additional loads. Joists supporting additional loads should be calculated by a competent person.