4x2 Treated Timber C24 Regularised Sawn Joist 47x100mm – 2.4m

Typically indicated in inches, the term "4x2" defines the joist size, (metric 47 x 100mm).  The regularisation process maintains uniformity along the timber's length, resulting in a "finished" size that is slightly smaller, generally around 45mm x 100mm, to ensure consistent dimensions throughout.

This slight variance is negligible and seldom affects most projects, remaining standard across 47x100, 4x2 regularised timber joists.

A popular choice for constructing decks, garden buildings, and featuring prominently in the walls, roofs, and floors of timber-frame structures due to the strength, regularised 4x2 timber joists are one of the most widely used timber joist size. 

Our timber joists are often referred to as “regularised” - meaning the lengths of timber are machine-finished to achieve a smooth finish and a uniform dimensions along the length of the timber joist. This can impact the finished size of the product by a few millimetres. The most common types of regularised timber joists are C16 and C24.

Kiln-dried refers to a process where timber or wood is placed inside a kiln to remove excess moisture from it. The controlled heat and airflow in the kiln facilitate faster and more uniform drying compared to air-drying methods. This process reduces the moisture content of the wood, making it lighter, stronger, less prone to warping or cracking, and more stable for various applications in construction, woodworking, or furniture making.

We provide both treated and untreated regularised 4x2 timber joists in a range of sizes: 2.4m, 3m, 3.6m, and 4.8m. While we strive to maintain stock across all sizes for delivery, there may be instances where we would supply a longer length as an alternative due to delay or unavailability of specific sizes in your region.

UK regularised timber is commonly categorised into two grades: C16 or C24. The "C" specifies the wood type: Conifer. The numerical value denotes the bend strength (determined by factors like imperfections and knots) C24 is the stronger grade of the two.

Typically, C16 timber joists are used in wall and roofing applications, while C24 is favoured for situations requiring exceptional strength, notably in roofing and flooring joists.

Opting for 4x2 treated timber is advisable for projects at risk of moisture or pest exposure. These timbers undergo pressure treatment, ensuring deep penetration of the treatment into the wood, providing durable protection against rot and pests. This selection is especially suitable for outdoor projects such as decking, roofing, and similar.