Browse the full range of C24 graded timber available from Nottage Timber Merchants, supplied direct from our yard in Bridgend, South Wales, with next-day delivery available across the South Wales area for orders placed before our daily cut-off.
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The Story
Treated sawn C24 timber 75mm x 225mm is a strength-graded structural section suitable for demanding load-bearing applications including floor joists, rafters, and ridge boards. Kiln dried to 20% moisture content or less, stress graded to BS 4978, and regularised for consistent sizing throughout.
Specifications
| Property | Detail |
|---|---|
| Material | Softwood (regularised sawn) |
| Treatment | Preservative treated |
| Grade | C24, stress graded to BS 4978 |
| Finish | Regularised (planed all round), eased corners |
| Nominal Size | 75mm x 225mm (3 inch x 9 inch) |
| Finished Size | Approximately 73mm x 220mm |
| Lengths Available | 3.6m (12ft), 4.8m (16ft), 6.0m (20ft) |
| Use Class | UC2 (treated, suitable for internal and covered external use) |
What it's used for
- Floor joists in new build and renovation projects requiring longer spans or heavier loads
- Roof rafters and ridge boards where C24 grade is specified by a structural engineer or building control
- Structural stud work and carcassing in timber frame construction
- Header beams and trimmer joists around openings in floors and roofs
Fitting and handling
Store timber flat on level bearers, off the ground, and keep it covered until installation to prevent moisture uptake. Although kiln dried to 20% or less, allow the timber to acclimatise on site for a minimum of 48 hours before fixing, particularly in heated buildings. Fasten using structural ring-shank nails or approved joist hanger fixings in accordance with your building specification, and ensure all cut ends are treated with an appropriate end-grain preservative before installation.
FAQ
What is the difference between C16 and C24 timber, and when do I need C24?
C24 has a higher bending strength and stiffness than C16, making it the right choice where spans are longer, loads are heavier, or a structural engineer or building regulations drawing specifies C24. For standard stud partitions and light-duty work, C16 is often sufficient, but for floor joists and rafters over longer spans, C24 is the safer specification.
Is this timber suitable for use in a roof or floor where building control approval is required?
Yes. This timber is stress graded to BS 4978 and regularised, which means it meets the requirements commonly called for by building control for structural applications. Always confirm the specific section size and span with your engineer or building control officer before ordering.
What are the actual finished dimensions of the 75mm x 225mm section?
The nominal size is 75mm x 225mm, which is also referenced as 3 x 9 inch in imperial. Once regularised, the finished dimensions are approximately 73mm x 220mm with eased corners. Allow for this reduction when planning joist hangers, noggins, or any close-tolerance joinery work.
Browse the full range of C24 graded timber available from Nottage Timber Merchants, supplied direct from our yard in Bridgend, South Wales, with next-day delivery available across the South Wales area for orders placed before our daily cut-off.
Description
Treated sawn C24 timber 75mm x 225mm is a strength-graded structural section suitable for demanding load-bearing applications including floor joists, rafters, and ridge boards. Kiln dried to 20% moisture content or less, stress graded to BS 4978, and regularised for consistent sizing throughout.
Specifications
| Property | Detail |
|---|---|
| Material | Softwood (regularised sawn) |
| Treatment | Preservative treated |
| Grade | C24, stress graded to BS 4978 |
| Finish | Regularised (planed all round), eased corners |
| Nominal Size | 75mm x 225mm (3 inch x 9 inch) |
| Finished Size | Approximately 73mm x 220mm |
| Lengths Available | 3.6m (12ft), 4.8m (16ft), 6.0m (20ft) |
| Use Class | UC2 (treated, suitable for internal and covered external use) |
What it's used for
- Floor joists in new build and renovation projects requiring longer spans or heavier loads
- Roof rafters and ridge boards where C24 grade is specified by a structural engineer or building control
- Structural stud work and carcassing in timber frame construction
- Header beams and trimmer joists around openings in floors and roofs
Fitting and handling
Store timber flat on level bearers, off the ground, and keep it covered until installation to prevent moisture uptake. Although kiln dried to 20% or less, allow the timber to acclimatise on site for a minimum of 48 hours before fixing, particularly in heated buildings. Fasten using structural ring-shank nails or approved joist hanger fixings in accordance with your building specification, and ensure all cut ends are treated with an appropriate end-grain preservative before installation.
FAQ
What is the difference between C16 and C24 timber, and when do I need C24?
C24 has a higher bending strength and stiffness than C16, making it the right choice where spans are longer, loads are heavier, or a structural engineer or building regulations drawing specifies C24. For standard stud partitions and light-duty work, C16 is often sufficient, but for floor joists and rafters over longer spans, C24 is the safer specification.
Is this timber suitable for use in a roof or floor where building control approval is required?
Yes. This timber is stress graded to BS 4978 and regularised, which means it meets the requirements commonly called for by building control for structural applications. Always confirm the specific section size and span with your engineer or building control officer before ordering.
What are the actual finished dimensions of the 75mm x 225mm section?
The nominal size is 75mm x 225mm, which is also referenced as 3 x 9 inch in imperial. Once regularised, the finished dimensions are approximately 73mm x 220mm with eased corners. Allow for this reduction when planning joist hangers, noggins, or any close-tolerance joinery work.
Browse the full range of C24 graded timber available from Nottage Timber Merchants, supplied direct from our yard in Bridgend, South Wales, with next-day delivery available across the South Wales area for orders placed before our daily cut-off.
