CLS versus c-16

tfer

As far as I know,all timber frame companies use cls timber for there studs if its a 140mm thick wall, I had a sales guy telling me that I could use c-16 studs instead, is this true ? as there is quite a large price difference

sydthebeat

C16 is a strength class of timber according to IS 444.
It ranges from C12 to C22 (going up in 2's)

TBH i dont know what CLS is.

tfer

thanks for the reply syd, would the c-16 be acceptable to build a timber framed house with ?

beyondpassive

For Joists and trusses, or closed panel, I'd be inclined to look for C24 for sitka spruce, High quality. Smaller knots and knot clusters. Low slope of grain and low tendency to distort.

price of imported timber went up recently so using Irish C16 is cost effective.

jutter_110

cls stands for Canadian Lumber Standard which is a demsional standard not structural.

tfer

so am I wrong in thinking timber frame companies here use cls ,or is it 140mm c-16 they use for the studs,? they do look very similar

cork2

ok CLS is used by timber frame companies but mainly so that the dimensions of the frames are uniformed. now c16 maybe be a bit low quality for framing id be going for at least c18 maybe even 20 and as long as your dpc's and membranes are suitable and fitted properly and treat the soleplates of you frames you should have no hassle.

also its it interior non load bearing c16 is grand. high quality for timber framed buildings and for structural or load bearing walls

Mellor

Strictly speaking, there is no reason why a section of timber couldn't be both graded C16 to IS444 and sized to CLS.

CLS (also called ALS) is not really to do with the type of timber, or the strength of timber.
It's the standard of sizes. In north america, CLS also is also responisble for the grading, it is done so both viaually and mechanically and would be very similar to IS444 (C16, C20 etc) or other euro equivalents.

galwaytt

tfer wrote: »

thanks for the reply syd, would the c-16 be acceptable to build a timber framed house with ?

In our experience, we haven't found what C16 we've been offered, acceptable. It's been too wet, too many knots/shakes, and for us dimensionally, too variable, and distorts like mad, over time.

beyondpassive wrote: »

For Joists and trusses, or closed panel, I'd be inclined to look for C24 for sitka spruce, High quality. Smaller knots and knot clusters. Low slope of grain and low tendency to distort.

price of imported timber went up recently so using Irish C16 is cost effective.

+1 on the C24, the difference in quality between that and C16 is night-and-day.

tfer

My engineer would be ok with me using c-16, but if tf companies are not using it, they must have good reason

Mellor

Your engineer is ok, as structurally is would be fine, it would need to be bigger than c-24 obviously. But it wouldn't be great from a practical POV for the guy having to qwork with it. See galwaytt's comments above.


What grade are the Tf company using (CLS isn't a grade/size etc)