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7x2 Treated Timber C24

7 x 2 treated timber, sometimes called 175x50 carcassing timber, is one of the basic components of the building trade. It is a quality C24 grade timber which has been cut to the required length and pressure-treated with substances that prevent attack by harmful fungi and insects. We supply high quality 7 x 2 C24 timber, which comes in 3m, 3.6m, 4.2m, 4.8m and 6m lengths and can then be sawn to whatever length is required for your project. Longer lengths of 7.2m are available on request.

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What is 7x2 timber in mm?

Here at Materials Market we list timber sizes in a couple of different ways. The most popular way is inches like 7 x 2 but we also use metric, which measures in millimeters (mm). For 7 x 2 timber this would be 175mm x 50mm or 47mm x 175mm. We sell 47mm x 175mm on this website and this is used interchangeably with 7 x 2 to refer to the same size of product. The slight discrepancy of 3mm between 47mm and 50mm just means that the finish at the ends is a lot more even and easier to work with.

What is 7x2 wood used for?

There are so many uses for 7 x 2 C24 timber as it is an incredibly versatile construction material ideally suited to both indoor and outdoor use, thanks to the sealing and treatment of the timber. 7 x 2 timber can be used in all kinds of ways including in both roofing and flooring applications, as well as for general joinery.


175x50 timber is most commonly used as carcassing timber for floor or ceiling joists. A joist is a load-bearing support that helps to make up the frame for a roof or floor space and will normally join opposing walls. They tend to run horizontally and bridge a gap over an open space. Joists generally outnumber beams. 7 x 2 timber joists are well-suited to this particular task as the C24 7 x 2 graded timber is sturdy and durable, making it suitable for structural purposes.

Some examples of how 7 x 2 timber lengths can be used are in 7 x 2 joists for the roof and floor, or as part of the wooden frame that ends up as part of the structural makeup of the building. This is a versatile construction material and its uses are as varied as you can make them. There aren’t any limitations that demand it is only used in the ways described above and it is often part of many buildings and carpentry projects in ways that we haven’t even touched on here. 

Explain the difference between 7x2 treated timber and 7x2 sawn timber?

Sawn timber is wood that has been cut to the required dimensions without being pressure treated and kiln dried. In the construction sector, pressure treated timber is popular as it provides many benefits, namely protection from adverse weather conditions.

The treatment process that imbues timber with 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 the elements. Following the treatment process, the timber lengths are put in an oven to be kiln dried.

It is very important to use treated timber rather than sawn timber for construction projects as the majority of the timber used in building is located where it isn’t easily inspectable, so you would have no way of knowing whether it was under attack from insects or if damp was encroaching.

Here at Materials Market, all four sides of the timber are planed to give them eased edges that are soft to the touch. An easi edge makes for 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 47mmx175mm, this product actually has a finished size of 45mmx170mm, but this difference is so negligible that it is commonly just referred to as 47x175, or 7 x 2.

Frequently asked questions about 7x2 timber

Can I paint 7x2 timber C24?

It’s certainly possible to paint treated timber but it does come with its own set of  complications due to the process involved and the chemicals used in the treatment process. An important thing to remember is that treated timber should not be painted immediately after it has been purchased.

This initially sounds counter-intuitive but it is solid advice because when shipped, most 7 x 2 C24 timber is still “wet” and time is needed for the chemicals to settle and dry. You will probably notice that the wood is initially rather heavy and feels damp to the touch.

If primer or paint is added while the wood is wet, it will most likely be rejected by the water based chemicals that are still active. It is therefore important to allow the treated timber to dry out fully before attempting to add any paint or primer to it.

In terms of time, it can be up to a few weeks before it is dry and ready to be used. This is largely dependent on where the wood is being stored. If there is too much heat or direct sunlight, this can cause the timber to warp rather than dry out. Conversely, damp conditions can lengthen the drying out period, prolonging the time before work can begin.

Is it easy to cut 7x2 treated timber to my preferred size?

It is relatively simple to cut timber to the size required, though appropriate power tools and a respirator are recommended for this task. The respirator should be worn to protect against tiny airborne particles of wood, contaminated with the chemicals used in the pressure treating process. These are obviously not recommended for human consumption. Likewise, eye protection should be worn in all such circumstances.

It should also be noted that treated timber cuts a little more like a wet wood so it is important to take extra care that the blade doesn’t slip while cutting it to the desired length.

Although it is a little more difficult than cutting regular, untreated sawn timber, it is not massively more difficult to cut treated 175x50 timber into the sizes that are needed for your project. As long as care is taken, it can be done fairly easily. This material is considered versatile with good reason, and if it was too difficult, it wouldn’t be used in so many different applications and projects.

How much does 7x2 sawn treated timber cost?

Carcassing timber is a very well-used and therefore relatively inexpensive building material. 175x50 timber prices are prone to fluctuation based on demand and we will be happy to provide you with a competitive quote if you wish to buy 7 x 2 timber through Materials Market.

Is 7x2 treated timber environmentally responsible?

We take great care to ensure that all of our treated timber 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 friendly sources.