4x3 Timber Treated

(3 Products)

Graded to C24 specifications, our 4x3 carcassing timber stands out as one of the finest choices for structural applications, including flooring joists, roofing, and timber frame stud walls. Compared to other classifications like C16 timber, this timber boasts fewer knots and reduced physical imperfections. Each piece of our 4x3 timber selection is precision-cut to size and undergoes pressure treatment with specialised chemicals, offering supreme defence against fungal decay and insect damage.

Find Out More About Our Types of 4x3
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What Is 4x3 Timber Used For? 

  • Structural applications
  • Flooring
  • Roofing
  • Timber framing
  • General joinery applications

4x3 Treated Timber Key Features

  • Pressure-treated to resist rot, mould and decay.
  • Graded to a superior C24 standard - excellent tensile strength and stability.
  • Versatile application ensures project flexibility. 
  • Regularised for ease of handling. 
  • Available in various lengths. 

4x3 Timber Sizing Explained

4x3 timber is most often measured in inches, which is an imperial measurement, though it is sometimes measured in metric and this is where millimetres (mm) come into play. 

The sizing of 4x3 timber is considered to be either:

  • Nominal Size: 75mm x 100mm
  • Finished Size: (approximately) 73mm x 95mm

This slight discrepancy is accounted for by the way the timber is cut, kiln-dried and prepared. The difference in the two sizes is minuscule and should not make a meaningful difference to your project. At Materials Market, we sell the finished size.

Whether you're after timber posts or floor joists, find it all on our timber page. For any specific requirements, such as a specific length or total meterage, get in touch with our friendly customer service team. 

Frequently Asked 4x3 Questions

How Is 4 x 3 Timber Treated?

4x3 softwood timber is usually treated using a process called pressure treatment. This involves placing the timber in a vacuum chamber where it's saturated with preservative chemicals. The pressure forces these chemicals deep into the wood, providing long-lasting protection.

Can I Paint Or Stain Treated 4x3 Timber?

Yes, you can paint or stain treated 4x3 timber. However, it's advisable to let the timber dry out for several weeks after purchasing, as the treatment process can leave it slightly damp. 

Using a primer before painting can also help the paint adhere better.

How Long Does 4x3 Treated Timber Last?

With proper maintenance and under typical conditions, 4x3 treated timber can last 20 to 40 years or even longer. Its longevity depends on factors like the quality of the treatment, environmental conditions, and how well it's maintained.

Is 4x3 Treated Timber Resistant To All Insects And Pests?

While treated timber is highly resistant to many common wood-destroying insects, like termites, and fungal decay, it's not entirely immune. Regular inspections and maintenance are essential to ensure its longevity.

How Should I Store My 4x3 Treated Timber?

Store your 4x3 treated timber flat, off the ground, and in a cool, dry place. If storing outside, it's best to cover the timber with a waterproof tarp to protect it from rain and direct sunlight.

Does The Treatment Affect The Strength Of 4x3 Timber?

The treatment process is designed to preserve the wood without significantly affecting its strength. However, always check the grade and suitability of the timber for your specific project.

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