7th Dec 2022 -

Commonly used for fence panels, floorboards, and fascias, 6x1 timber beams serve a variety of non-structural uses within construction. In this overview from Building Materials Nationwide, we’ll explore how timber sizing works within the UK, the types of 6x1 timber commonly sold, and some of its most popular uses.

How Will 6x1 Timber be Sold in the UK?

When shopping for 6x1 timber in the UK you will see it listed as 150mm x 25mm. This is because metric sizes must be used on product listings. Imperial sizes continue to be used informally in the UK and officially in other parts of the world. 150mm x 25mm is not actually an exact match for 6x1 (152.4mm x 25.4mm would be more accurate) but this will be the option sold. 

It’s worth keeping in mind the differences between nominal and actual timber sizes when shopping. The specified sizing of a timber beam is the size that it will be rough sawn to when felled. This is known as green timber, and will be unsuitable for most construction purposes, as it will shrink dramatically over time when drying. To reduce the moisture content before sale, timber will typically be kiln-dried, a process that looks to take the moisture levels below 20%. Kiln-drying will reduce the size of each timber beam. If you buy planed timber this will also be smaller than the listed size. Planing involves sanding rough sawn timber to give a smooth and attractive look on one or more facing. This will necessitate reducing the dimensions of the timber. When buying a 6x1 timber beam within the UK, the dimensions in mm will actually be around 140mm x 19mm.

What Lengths of 6x1 Timber Are Available?

6x1 timber is sold in varying lengths, typically in 60cm increments. These lengths will vary from around 2.4m to 4.8m, depending on your timber merchant.

What Types of 6x1 Timber Are Sold?

While 6x1 timber sold in the UK will almost always be kiln-dried, you will typically have a choice of options based on both grading and finishing, that can bring key benefits to specific construction uses.

PSE 6x1 Timber

As stated earlier, planing involves smoothing one or more surfaces of a piece of timber. This serves two purposes, giving a smooth appearance and avoiding the risks of splinters. For visible uses in a project, or uses where people will come into contact with it, planed 6x1 timber is the best choice. PSE, or planed square edge timber, will have been planed on each face, leaving sharp corners between edges.

Treated 6x1 Timber

Pressure treated timber, sometimes called tanalised timber, is coated with preservatives within a vacuum chamber, designed to boost its moisture and insect resistance. Untreated softwood timber is prone to rot and decay when it comes into contact with moisture, and wood-boring insects pose a threat to the look and stability of any timber construction. In areas where moisture or insects pose a risk, opting for a tanalised timber can ensure long term performance.

What Are the Popular Uses for 6x1 Timber?

The long, flat shape of a 6x1 timber beam makes it specifically suited for certain uses within a building project.

Fence Panels

6x1 timber can be used within fencing, such as for featherboard fencing panels. When secured together they will offer a solid level of strength, whilst having an attractive appearance within a garden. For external use, you should be looking to use a treated 6x1 timber, as untreated softwood will quickly rot. Rough sawn timber can be used to create rugged fence panels.


When looking for traditional wooden floorboards within a building, 6x1 timber will make a great option. With the joists underneath supporting the weight of the floor, 6x1 will be thick enough for a long-lasting installation. You should be looking for PSE timber when sourcing floorboards, both to give an attractive look to your flooring, and to avoid the risk of leaving splinters in peoples’ feet.

Barge Boards and Fascia Boards

Barge boards and fascia boards are solid boards installed beneath the roof of a house externally, with 6x1 timber being a suitable choice. Fascia boards are straight and will also carry the gutters, while barge boards are diagonal under a gable end of a property. Due to the moisture from both the rain and the guttering, opting for treated timber is vital for these uses.

We Are Nationwide Timber Suppliers

Building Materials Nationwide supplies quality timber products across the UK, sold at competitive prices. We stock 6x1 PSE timber, alongside CLS timbertreated timber, and structural timber. For customers within the building industry, we also offer trade accounts, granting access to our network of suppliers, our express delivery options, and the services of a dedicated account manager. Sign up for a trade account through our website today.