Loft (attic) flooring question

[Deano12]

Hi

I wonder if anyone can help me. We are boarding out a loft (attic) for further storage space. Can anyone tell us if there is a rule of thumb for knowing if it is safe to just fit chipboard to the existing timbers (ceiling beams) before needing to suspend the new floor. I'm guessing it will depend on the timber section and their pitch. But can anyone give me a guide to the timber sections that would be adequate?

Here's hoping

[Amanda_931]

I once lived in a house where the attic storage--reached by pull-down stairs--was on loose sheets of plywood (back in the days before OSB).

Is is really necessary to suspend a floor just for storage--or even unless someone were living up there tromping around and annoying the people downstairs.

[jraabe]

Most ceiling joists are designed to hold only about 15#/sf, which is plenty for insulation, drywall and a bit of lightweight storage (the empty suitcases and Xmas decorations).

If you are planning a loft where people will be up there walking around you should have a floor structure that can support at least twice that.

You may be able to get that by doubling up the attic joists, but you should have someone who knows structural design check out the spans and what is needed for your situation.

[Deano12]

Thanks Amanda, thanks John. It's only for storage. I just know that in some old houses, their joists are very small sections. My brother is a joiner and his rule of thumb is:

Normally if the room is to be used just as storage – you can just board it out. If it is to be used as living space then you have to look at the ceiling timber sections. If it is 3 x 1, 3 x 2 or even 4 x 1 1/8 then a suspended floor is needed. The sections need to be 4 x 2 or 6 x 2 and above.