Flooring a garage loft?

[blanko]

I'm looking to floor the loft area at the back on my garage - the ceiling of the utility room below.

I'm wondering what the thinnest material I can use for the job is? I can get two complete 8x4 sheets in there for the job as access is good.

11mm OSB?or 12mm ply?

18mm seems overkill as it will be used for light storage, although, I will need to climb right in there to insulate the rafters above at some stage...

The joists are 4x2's and are 400 mm apart. About 9 foot long, supported only by the block walls at each side of the garage, no supports in place.

Thanks.

 

[blanko]

Bump for any thoughts on this...

 

[Diver Fred]

Ask yourself - will I be up there frequently (more than once a month)? If yes then 18mm ply is the way to go. Less than that then you may be able to use thinner material; just boldly and idelibly mark where the supporting joists are and only walk on those markings once in place.

 

[Ian H]

What's the price difference between 12and 18mm?

 

[JohnD]

depends where you go. A place near me often has shuttering ply on clearance. A bit rough, but strong. Might be returned or overstock.

 

[blanko]

Thanks, I think I'll mark out the joists and go with the thinner material, I'll be up there once a year probably and can reach most things stored up there without climbing in.

It's not just the price of the wood, 18mm means more weight on the joist also and if I don't need it, why buy it?

 

[Tigercubrider]

You should insulate first, and ensure that the joists are extended so as to not crush the insulation

Believe me- once you floor it and get a couple of boxes up there you will never gat round to adding insulation