Gary Cavie wrote:
Hi,

Could anybody who has access to the regs for unsupported timber span
sizes, give me an idea as to what size timbers I need for a floor? It
will be 3300mm between supports, spaced at 400mm, and will be used for a
shed / workshop (no particularly heavy equipment, just desk / chair /
electronics workbench etc).

Floor on top will be 18mm bitumenised OSB, with insulation between the
joists.

If I increase the spacing to 600mm, does that make much of a difference?

Thanks for the help

Gary
In Impeial peak, the rule of thumb is that, for a 2 inch thickness, at
16inch centers, the size (in inches) is the span (in feet) divided by 2
plus 1. e.g for a 12 foot span, 12/2 =6 +1, so a 7x2 joist is needed. I
stress that this is a rule of thumb.
Malcolm