The Story
C24 structural timber in 47mm x 200mm (8x2) section is one of the most widely specified sizes for floor joists, roof rafters, and load-bearing frames in UK construction. Sawn, kiln dried to 20% moisture content or below, and regularised for consistent sizing, this grade meets the demands of long spans and heavy loads.
Specifications
| Material | Softwood (structural carcassing timber) |
|---|---|
| Grade | C24 strength graded |
| Treatment | Kiln dried to 20% moisture content or below |
| Finish | Regularised with eased edges, approximately 45mm x 195mm finished |
| Nominal Size | 47mm x 200mm (8 x 2 inch) |
| Finished Size | Approx. 45mm x 195mm |
| Lengths | 3.6m, 4.2m, 4.8m, 6.0m |
| Profile | Sawn regularised |
What it's used for
- Floor joists in new-build and renovation projects where C16 or smaller sections fall short of span tables
- Roof rafters and purlins on pitched roofs requiring a deeper section for structural integrity
- Loft conversions and structural flat-roof decking subframes where load capacity is critical
- Load-bearing stud work, beams, and general structural framing in residential and commercial builds
Fitting and handling
Store timber flat and off the ground on level bearers, under cover, with adequate air circulation on all sides to prevent distortion before installation. On site, allow the timber to acclimatise to the ambient conditions for at least 48 hours before fixing, particularly in heated interiors. Fix with structural ring-shank nails or timber screws appropriate to the load; refer to the relevant span tables in BS 8103 or your structural engineer's specification when sizing joists or rafters.
FAQ
What is the difference between C16 and C24 structural timber?
C24 timber is strength graded to a higher classification than C16, meaning it has greater bending strength, stiffness, and load-bearing capacity. For longer spans or heavier loads, a structural engineer or span table will typically specify C24 where C16 does not meet the required performance.
Is this 47mm x 200mm timber suitable for floor joists?
Yes. The 47mm x 200mm (8x2) section is one of the most common sizes used for floor joists in UK residential construction. Its depth gives the span capacity needed for most domestic floor layouts, and C24 grading ensures it meets standard UK building regulation requirements when installed to specification.
What does regularised mean on sawn structural timber?
Regularised timber has been passed through a planing process on its two face sides to bring it to a consistent depth, finishing at approximately 195mm rather than a variable sawn dimension. Eased edges reduce splintering during handling. The faces remain sawn in texture. This consistency is important when setting out joists to a level floor or ceiling datum.
Order C24 structural timber from Nottage Timber Merchants
Nottage Timber Merchants supply C24 graded timber direct from our yard in Bridgend, South Wales. Trade quantities are welcome, with competitive pricing and prompt despatch to the local area. Browse our full range in the C24 graded timber collection for additional section sizes and lengths.
Description
C24 structural timber in 47mm x 200mm (8x2) section is one of the most widely specified sizes for floor joists, roof rafters, and load-bearing frames in UK construction. Sawn, kiln dried to 20% moisture content or below, and regularised for consistent sizing, this grade meets the demands of long spans and heavy loads.
Specifications
| Material | Softwood (structural carcassing timber) |
|---|---|
| Grade | C24 strength graded |
| Treatment | Kiln dried to 20% moisture content or below |
| Finish | Regularised with eased edges, approximately 45mm x 195mm finished |
| Nominal Size | 47mm x 200mm (8 x 2 inch) |
| Finished Size | Approx. 45mm x 195mm |
| Lengths | 3.6m, 4.2m, 4.8m, 6.0m |
| Profile | Sawn regularised |
What it's used for
- Floor joists in new-build and renovation projects where C16 or smaller sections fall short of span tables
- Roof rafters and purlins on pitched roofs requiring a deeper section for structural integrity
- Loft conversions and structural flat-roof decking subframes where load capacity is critical
- Load-bearing stud work, beams, and general structural framing in residential and commercial builds
Fitting and handling
Store timber flat and off the ground on level bearers, under cover, with adequate air circulation on all sides to prevent distortion before installation. On site, allow the timber to acclimatise to the ambient conditions for at least 48 hours before fixing, particularly in heated interiors. Fix with structural ring-shank nails or timber screws appropriate to the load; refer to the relevant span tables in BS 8103 or your structural engineer's specification when sizing joists or rafters.
FAQ
What is the difference between C16 and C24 structural timber?
C24 timber is strength graded to a higher classification than C16, meaning it has greater bending strength, stiffness, and load-bearing capacity. For longer spans or heavier loads, a structural engineer or span table will typically specify C24 where C16 does not meet the required performance.
Is this 47mm x 200mm timber suitable for floor joists?
Yes. The 47mm x 200mm (8x2) section is one of the most common sizes used for floor joists in UK residential construction. Its depth gives the span capacity needed for most domestic floor layouts, and C24 grading ensures it meets standard UK building regulation requirements when installed to specification.
What does regularised mean on sawn structural timber?
Regularised timber has been passed through a planing process on its two face sides to bring it to a consistent depth, finishing at approximately 195mm rather than a variable sawn dimension. Eased edges reduce splintering during handling. The faces remain sawn in texture. This consistency is important when setting out joists to a level floor or ceiling datum.
Order C24 structural timber from Nottage Timber Merchants
Nottage Timber Merchants supply C24 graded timber direct from our yard in Bridgend, South Wales. Trade quantities are welcome, with competitive pricing and prompt despatch to the local area. Browse our full range in the C24 graded timber collection for additional section sizes and lengths.
