Treated Sawn Reg Timber C24 Graded Kiln Dried 47mm x 200mm

Treated C24 graded timber in 47mm x 200mm is a heavy-section structural softwood, kiln dried to 20% moisture content or below and pressure treated (Tanalised) for lasting performance. A reliable choice for floor joists, flat roof joists and load-bearing frameworks where span and strength matter.

Specifications

What it's used for

• Floor joists in ground floors and suspended timber floors where long spans and higher loads are specified
• Flat roof joists and pitched rafter systems requiring C24 structural certification
• Decking subframes and bearer systems, particularly where ground contact or exposure to moisture is a factor
• Heavy-duty internal frameworks, stud walls and structural carcase work in new build or renovation projects

Fitting and handling

Store timber flat and fully supported off the ground under cover before installation, allowing air to circulate around each length. Because this timber is kiln dried, it is dimensionally stable, but stacking it in the conditions where it will be used for a few days before fixing will minimise any seasonal movement. When fixing, use joist hangers, structural screws or ring-shank nails appropriate for use with treated timber, as standard bright-steel fixings can corrode when in contact with the preservative treatment.

FAQ

What is the difference between C16 and C24 graded timber?

C24 has a higher strength classification than C16 under BS 4978, meaning it can carry greater loads over longer spans. It is generally specified by engineers and building control for floor joists, rafters and structural members where a structural calculation has been carried out.

Is this timber suitable for decking subframes and outdoor use?

Yes. The Tanalised pressure treatment gives this timber UC3 durability, making it suitable for above-ground external applications including decking subframes, pergola frameworks and exposed structural work. It should not be used in direct ground contact without further specification.

Will 47mm x 200mm C24 timber meet building regulations for floor joists?

C24 graded timber meets the structural requirements referenced in Approved Document A. Whether 47 x 200mm is the correct size for your floor joist depends on span, spacing and load, which should be confirmed against the TRADA span tables or by your architect or structural engineer.

Browse the full range of C24 graded timber at Nottage Timber Merchants. We supply trade and retail customers from our yard in Bridgend, South Wales, with next-day delivery available across the South Wales area on stocked lengths.