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5x2 Treated Timber C24

5x2 treated timber, also referred to as 47x125 treated timber, is a natural product that is a common purchase of the building trade. This is high quality C24 graded timber which has been sawn to the required length and also been subjected to a pressure treatment with special chemicals to resist attacks by insects and fungi. We are sellers of 47x125 timber, which comes in various lengths of 2.4m, 3m, 3.6m, 4.8m and 6m. From there it can be cut or sawn to whatever length is required for your project. Longer lengths are available on request.

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What is 5x2 wood used for?

There are multiple applications for 5 x 2 C24 timber as it is incredibly versatile and is considered to be suitable for use both in and out of doors, thanks to the sealing treatment given to the timber. 5 x 2 treated timber can be used in all manner of different ways including in both flooring and roofing.

A few examples of the ways in which 5 x 2 timber lengths can be used are in joists for the floor or roof, or as part of the timber frame that is a major part of the structure of a building. Treated timber is adaptable and the uses for it are as varied as your imagination can make them. 


With its structural C24 grade 5 x 2 timber can be used as carcassing timber in floor joists, or as timber framing that is an integral part of the structure of a building. It can also be used in roofing applications, as rafters or as. joists in a loft floor.

Garden furniture is a major use of treated timber as the way the sealing treatment protects the wood makes it ideal for sustained outdoor use. 

Where are 5x2 timber joists used?

5 x 2 timber joists are used in roofing, flooring and decking, so there are many different scenarios in which they could be useful. They provide an important supporting framework for building out the floor or ceiling and are often used to span gaps and open spaces. They are ideal for construction work and weight bearing tasks due to the strength and sturdiness of the C24 graded timber that has been used to make the joists.

What is the difference between treated timber and sawn timber?

Sawn timber is wood that has been cut to the required dimensions but hasn't been pressure treated and kiln dried. In the building sector, pressure treated timber is popular as it provides many benefits, namely protection from the elements.

The process that gives treated timber the insect and fungi resistance often includes copper and organic co-biocides which aim to repel both insects and moisture and render a high degree of sustained protection against both of these common problems. Treated timber is sometimes referred to as tanalised timber, which takes its name from the preservative (tanalith E) that is used in the treatment process. Following the treatment, the timber lengths are put in an oven to be kiln dried.

It is considered to be important that we use treated timber for most kinds of construction project, as the vast majority of the timber utilised in building is in places that are not easy to view, so we don’t have an easy way of knowing if it is under attack from insects or whether damp is seeping into it.

Here at Materials Market, all our timber is treated with preservatives, kiln dried, and then planed on all four sides to give it eased edges that make easy handling. Timber comes in various lengths and sizes, and is regularised to ensure that dimensions are kept consistent within ranges. With a nominal size of 47mmx125mm, this product actually has a finished size of 47mmx120mm, but this difference is so negligible that it is commonly just referred to as 47x125, or 5x2.

Frequently asked questions about 5x2 timber

Is it possible to paint 5x2 treated timber?

It is possible to paint most building materials and treated timber is no different in this regard. Like many other materials, treated timber comes with its own set of challenges. This is mainly because of the treatment process involved and the chemicals used to protect it. An important point to remember is that it isn’t a good idea to paint treated timber too soon after buying it.


When it is delivered, most 5x2 timber C24 is still “wet” and time is needed for the waterborne chemicals to settle and dry. The treated timber is heavy and feels damp to the touch at this point.

If primer or paint is added to it at this juncture, it will not work very well and will most likely be rejected by the water based chemicals that are still drying in the wood. It is a good idea to allow the wood to dry completely before adding any paint or primer to it. This can take up to a few weeks depending on the environmental conditions at the storage area. Heat and direct sunlight can cause the treated timber to warp instead of dry out and damper conditions can prolong the drying out period. 

Will I be able to cut 5x2 treated timber to my preferred size?

Cutting treated timber to the size that you need in your project is relatively simple, though you should only attempt this with the appropriate power tools. A high quality respirator should be worn as there will be miniscule airborne slivers of wood, coated with the chemicals used in the pressure treating process. We also highly recommend using suitable eye protection.

It is important to prevent ingestion of the wood particles so please heed all necessary safety precautions before proceeding to attempt to cut the treated timber. Another quirk of treated timber is that it cuts a little more like a wet wood, so additional care must be taken to ensure that the blade doesn’t slip while cutting.

It is a little more difficult than cutting regular sawn timber, to cut treated 50x125 timber into the sizes that are needed for your project, but not hugely so. As long as care is taken with the extra challenges posed, it can be accomplished relatively easily. This material is popular for a reason and if it was very difficult, it wouldn’t be used in so many different applications and projects.

What is the cost of 5x2 sawn treated timber?

Sawn carcassing timber is a popular and therefore relatively inexpensive building material. 47x125 timber prices can be prone to some fluctuation now and then, depending on demand. We will provide you with a very competitive price if you wish to buy 5 x 2 timber through Materials Market.

Is 5x2 treated timber environmentally responsible?

All of the treated timber for sale on the Materials Market website is Forest Stewardship Council (FSC) or Programme for the Endorsement of Forest Certification (PEFC) certified, which means that our timber is responsibly sourced from environmentally responsible suppliers.