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75 x 100mm Treated Timber C16/C24 Graded Kiln Dried and Regged

75 x 100mm Treated Timber C16/C24 Graded Kiln Dried and Regged

Product Code: T039
Reward Points: 10
Price: £12.20
Ex Tax: £10.17
Price in reward points: 1017

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* Timber Lengths:


4x3 Treated Timber C16/C24 Grade

Often referred to as 4 x 3 treated wood or 3 x 4 treated timber, this is in relation to the old imperial sizes of 3 inch by 4 inch and 4 inch by 3 inch. Sold by the stated nominal size of 75 x 100mm, this treated sawn carcassing actual finishes around 70 x 95mm but may vary slightly. Once the treated sawn timber is regularised (regged) it gives a finished edge that takes 2mm from nominal thickness and 5mm from the nominal width. This process means the lengths are easier to handle as the finish has slightly rounded edges.

What is the difference between C16 Treated Timber and C24 Treated Timber?

A pressure treated 4x3 timber must be used for jobs such a roofs when there is the potential for rot, insect attacks or any other form of decay. Care must be taken to select the correct grade of timber.

Both C16 and C24 are kiln-dried softwood options, but understanding their differences and whether or not the timber needs to be treated are crucial for a successful construction project.


Think of the grades as tiers of excellence. C24 reigns supreme, embodying the pinnacle of strength and impeccable quality, deserving of the number 1 spot. C16, while formidable and dependable, occupies the second level, acknowledging its slight shortcomings compared to the gold standard.


Need the strongest capabilities? C24's the one as it is perfect for heavy-duty projects like load-bearing walls or beams. C16, while still robust, works best for less demanding tasks like stud walls or internal structures.

Key things to remember:

Both options offer solid construction durability. Choose the one that best suits your project's specific requirements. If you're unsure, just ask.

Considerations that effect grading:

• Knots - More knots mean less strength
• Insect damage or woodworm holes
• Shakes or splits along the grain of the wood
• Slope of the grain
• Wane - bark or a lack of wood fibre on the edge of a piece of lumber

As C24 treated timber is visually graded the should be less imperfections making it an all round better quality product.

Due to the increasing demand, most regions will now supply 4 x 3 C24 treated timber. If you have a critical requirement, please check before buying. In some areas, 4 x 3 C16 treated timber will be supplied

What is 4x3 Pressure Treated Timber?

The timber is treated with high pressure Tanalith E or similar preservative to protect against rot, insects and fungus. This also maximising life-span of timber when compared to untreated timber.

England and Wales Timber Treatment Use Class 3. Scotland Timber Treatment Use Class 2

What is 4 x 3 Treated Timber used for?

The most common use would be as a timber wall plate. This is fixed with Restraint Straps to the masonry so the roof timbers can be fixed in place. It is also perfect for applications such as:

• Stud walling

• Timber rafters

• Roof joists

• Heavy duty furniture building

If you need to know more about 4x3 sawn timber, we have great timber for roofing blog.

If you're planning on using 3x4 treated timber for joists, care must be taken to ensure the clear spans are suitable to take the required load. If you're not sure, check the Span Table.

What lengths are available in 75 x 100 treated timber?

Sizes listed in the drop-down menu are:

• 4x3 treated timber 2.4m
• 4x3 treated timber 3m
• 4x3 treated timber 3.6m
• 4x3 treated timber 4.2m
• 4x3 treated timber 4.8m
• 4x3 treated timber 5.4m
• 4x3 treated timber 6m

**Please note, all sizes in the menu may not be available as it depends on regional stock. If you require any length over 4.8mtr, please contact us before making a purchase as longer lengths are only available from selected locations.**

If this is the case, you will be contacted within 1 working day to discuss the options.

3x4 treated timber in mm is considered to be 75x100mm but as previously mentioned the actual size C16 treated timber supplied would finish around 70 x 95mm.

Don't want treated timber 4x3? For treated timber supplies across the whole of the UK, Buildershop can help source most sizes and grades. By clicking on C16 Kiln Dried Graded Timber - Treated you'll see the most common sizes. If the size you require isn't listed on our website, please get in touch and we'll be happy to try and help.

For full details of delivery charges, returns, colour variations, and discounts please see our delivery & returns policy.

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