22mm or 18mm T&G Chipboard....?

[Capable Noob]

I've just installed new attic trusses at 400 centres and am looking at floor options.  The "room" is 17 x 5m (to be divided up with stud walls).  I've heard that 22mm is a must for 600 centres but for 400 centres I could use 18mm... I just wondered what people's thoughts are on 18mm vs 22mm?  I've not priced up each yet but as they say in King's Cross, twenty quid's twenty quid... 😉

[markc]

Is this for storage or usable rooms? Were the trusses designed for the floor loading? Or are they ordinary roof trusses?

[Capable Noob]

Sorry, should have been clearer - they're attic trusses designed to be usable rooms (bedrooms and bathrooms).

[Mr Punter]

You can use either but I would go 22mm.  Egger Protect is good.

[markc]

2 minutes ago, Capable Noob said:

Sorry, should have been clearer - they're attic trusses designed to be usable rooms (bedrooms and bathrooms).

Great, in that case go for the 22mm, floor will be much more rigid and the extra cost is minimal

[Capable Noob]

Thanks.  That was kind of what I was thinking, but thought I'd check in case the consensus was that it wasn't necessary.  It's another of those things where you could save a few quid now but in the future you wish you'd spent the extra.

[markc]

You only regret buying 22mm when you are carrying them up a ladder .. or carrying them anywhere come to think of it.