Thread: Newbie Question

Originally Posted by BALDAGGIO

hELLO fOLKS,
Mr Newbie to this group, and to home reno in general.
I have begung the reno of home, and draftsman has specified on floor plan "90 x 35 F17 SHW joists.
I get the 90 x 35 part but F17 and particularly SHW......what does that mean.

Thanks in advance

Baldaggio

As far as I know F17 is the flexibility of the timber and SHW is Southern Hard Wood? (someone correct me if I'm wrong) So the Draftsman would have specified that type of Joist for its strength over a large span in accordance with law...
Also I think there's a Renovation section in this forum...

Originally Posted by Pra33

Also I think there's a Renovation section in this forum...

Yes and No, there used to be but it now has its own domian now

Renovation Forum

Hi Baldaggio. As Pra33 has said, the f17 refers to the "stress grade" of the timber - in other words the ultimate flexural strength of timber in engineering terms for load bearing capacity, spanning capability etc.

Generally, the higher the number the higher the stress grade or strength of the timber. Radiata Pine is usually graded around f5 or f7, while some select grades of seasoned clear Douglas Fir (Oregon) can go as high as f11 - which is about the maximum achievable for softwoods. Our Australian hardwoods are superb engineering timbers, most species starting at around f14 and going right up to f27 and beyond

Seasoning is an important part of any timber's ultimate strength, and is an important factor in the stress grade applicable to any species. All timbers beyond f14 would generally be Seasoned Hardwood (SHW). Your designated timber will refer to a seasoned species of hardwood - many of which may be suitable for your requirement, depending on their exposure to the elements. Our hardwood species also have differing durability grades, which make some of them suitable for external use in decking, posts etc, and others suitable for internal framing.

The "f" (flexural) rating is being somewhat overtaken by the MGP rating system these days, but most builders, engineers and timber merchants are still using f5 as a recognised standard for radiata framing timber.

Originally Posted by Pra33

As far as I know F17 is the flexibility of the timber and SHW is Southern Hard Wood? (someone correct me if I'm wrong) So the Draftsman would have specified that type of Joist for its strength over a large span in accordance with law...
Also I think there's a Renovation section in this forum...

I would have guessed Seasoned Hard Wood as opposed to green wet stuff.
Also 90 x 35 sounds a little skinny but then I dont know where in the house it is going.

Ross