Strength Grades

[sebmaster]

Hi,

Ive been trying to read about timber strength grading, I have found a number of tables and recommendations talking about the grades and cross sections required for things like decking and floor spans, but I wondered if someone could explain what strength grading means practically in more general terms?

Do different strength grades define things like the compression and rotational forces the timber can take? Is there somewhere I can find a list of these?

Thanks!

 

[freddiemercurystwin]

http://shop.build-center.co.uk/buil...3 TRAInSheetSheetTimberStghSpansA4Build_1.pdf

 

[sebmaster]

Hi freddymercurystwin,

I've seen that one and it is useful. But i'm wondering how they determine the span lengths.
I take the lengths are based on a constant weight applied to the centre of the length, the max at which that grade at that CSA can safely take?

But as seen from the tables the distances between the joists also define the span lengths, what about selecting strength grades for arbitrary applications, where you would want the force applicable to a single length of timber?

EDIT: Ive seen the sizing applications on the TRADA website but these are for members only and I think that means 'subscribers' as opposed to simply registered members.