Loft (raised) joists... getting the right wood... (C16/C24/Treated/PSE)

[wasdonkey]

OK, so I'm undertaking a fairly straightforward loft board project for light storage - which requires raising joists about 7 inches to accommodate the considerable amount of insulation up there!

I've been searching for what type of timber people use. I see loads and loads of posts about joists and doing the job I'm doing, but none that detail what type of timber (other than the size) they're using...

The reason I ask is, because I ordered some C24 structural 7x2 lengths. They turned up today (tanalised/treated) looking a little wet, green and pretty heavy (looks like this stuff has been kept in the yard) and I'm skeptical about using wet wood that'll dry out, twist, shrink etc and pull my roof frame out of shape as well as loading it up with heavy wet stuff. I'd usually use this type of wood for outdoor use. Comparing against the frame already in my loft, that looks to be non-treated PSE - but again, reading the forums, PSE doesn't looks to be good for structural use?

All c16/c24 I can find seems to be treated, which I associate with outdoor use... PSE or treated for the perpendicular joists... that's the question?

 

[freddiemercurystwin]

Structural timber is OTT, all you need is something as light as possible.

 

[wasdonkey]

OK, so joist = structural is a bad assumption?

With more searching, I have found more threads with similar questions, but still none with solid answers... 'it'll do' or 'I wouldn't reccomend that' is all I can find...

What's the right material to use? i.e. if I paid a decent tradesperson to do the job correctly, what timber are they going to turn up with?

 

[Why Not Indeed]

OK, so joist = structural is a bad assumption?

Not necessarily, but the application here is "light storage", which implies low loadings.

Not sure if you're at the point where you're able to return the timber, but if you were to proceed with this timber, I suggest you let it acclimatise first in the place where you're planning to use it.

Also check the approach in post 2 of this thread:

Strengthening Loft floor

I am looking into having my loft converted for storage. I want the floor boarded, roof plasterboarded and loft ladder installed. The loft currently is full of a lot of boxes possibly 100kgs worth. I have had someone come round to quote for the work and they have advised me ''that...

www.diynot.com

 

[RandomGrinch]

Also check the approach in post 2 of this thread

I followed the advice from Tony1851, and I used C16's (they were cheap enough from TP).
As above, I let them acclimatise first.
Any that became warped, I used for noggins.