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Editorial

C16 vs C24 timber

C16 and C24 refer to the strength grade of a piece of carcassing timber.


There are 12 strength grades as set by the British Standard in the BS 5268, but the most commonly specified are C16 and C24.


Both grades are used in structural applications and are suited to different loads. They can be used for rafters, floor joists, studwork for partition walls, formwork, shuttering etc…


Bob Tee, our Timber Products Manager has more.

What’s the difference between C16 and C24? 

Most imported graded carcassing timber these days tends to be heavy to C24 grade.

Whilst C16 graded timber is strong enough for some applications such as wall plates, studwork, rafters, joists etc…C24 comes with added benefits.

C24 timber has been graded to a higher standard than C16. It’s a premium piece of timber that can handle higher loads and wider spans.

C24 grade can only be achieved by importing timber from areas where the climate forces a slower growth rate and hence a tighter grain.

All Elliotts branches stock C24 graded carcassing as standard.


Quick-fire Q&A

If you cut C16 or C24, does it lose its grading?

Yes. If it’s re-sawn in its cross-section or thickness, then its strength grade could be lost. Both pieces of timber will need re-grading before they can be used.


I need C24 grade timber, but I can’t see a stamp on the wood?

Don’t use it. All graded timber will have a C16 or a C24 grade stamp on the face of the timber.


Is carcassing timber treated? 

All Elliotts graded timber is kiln-dried and then pressure treated against insect and fungal attack.  

What carcassing sizes do you sell at Elliotts?
Thickness Width Grading Treated
100mm 100mm C24 Grade Yes
75mm

100mm

150mm

200mm

225mm

C24 Grade Yes
47mm

50mm

75mm

100mm

125mm

150mm

175mm

200mm

225mm

250mm

C24 Grade

Except 47 x 500mm and 47 x 75mm

Yes
22mm

75mm

100mm

150mm

200mm

Ungraded
Yes

Speak to your local branch to get information on stocks

Or speak to Bob Tee for help with your timber project.

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