Maximum slop3 10 deg.
Timber joist flat roof.
Eurocode 5 span tables for solid timber members in floors ceilings and roofs for dwellings 3rd edition.
Supporting imposed load for access and repair only.
Floor joists flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.
The joists should be sized using either the trada span tables or bs en 1995.
At least 40mm bearing on supports.
Tables 1 and 2 in this chapter are derived from the trada technology ltd.
Joist breadth 47mm.
For additional stability you can also use steel joists that are built into one or both of the walls.
If insulation is placed on top of the flat roof joists and as such the joists are not fastened to the boarding above the depth to width ratio should not be greater than 4.
Span is clear span between supports.
For timber floors between homes.
Span tables for solid timber joists.
The section sizes are based on regularised als or cls timber.
This will give additional stability to the roof structure.
The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls.
The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure.
Notches are not to exceed 0 125 of the depth of the joist and are to be located between 0 07 and 0 25 of the span from the support.
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.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
1 2 timber strength class and joist size.
Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading.
Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Depth to width ratio should not be greater than 6.