21 Feb

Understanding Timber Grades

Timber grades mark the quality of timber to help users find the right type for their needs. Understanding the timber grades is key to ensuring you receive wood of a suitable strength, moisture content and aesthetic. 

As leading providers of timber across London, we know a thing or two about timber grades. Discover everything you need to know about timber grading in this month’s article, and make sure you get the best timber for your buck.

Understanding timber grades

What is meant by timber grade?

Timber grades are a rating provided to quickly identify the quality of the timber. All timber will come with a label detailing the type of timber, the condition and the strength class. 

The strength class may be graded by visual inspection or machine. Visual inspection was the original method of grading timber and is still the preferred method for spotting natural strength-reducing features such as knots, wanes and slopes. Machine grading is typically used for grading high volumes of timber of similar species and cross section. You will know if your timber has been machine graded because the label will show a letter ‘M’ below the strength grade.

There are twelve official strength grades as set by the British Standard BS 5268, but the two most common are C16 and C24.

What is C16 timber?

Timber with strength grade C16 is kiln dried to minimise the amount of moisture in the wood. This provides it with great strength while also allowing it to be bent and compressed for construction. 

C16 is popular because it is strong, versatile and relatively cost effective, but it also has some defects, including occasional grain deviations, sap stains and uneven surfaces.

What is C24 timber?

C24 is a superior grade to C16 and therefore indicates timber of greater strength, resilience and appearance. C24 timber is better suited to handling heavy loads and wide spans. 

C24 is usually taken from areas where the climate forces a slower growth, hence producing a tighter grain.

Where can I find the information for timber grade?

Timber grading will be included on the product and should be communicated to you before you order. Along with the strength grading, you’ll also find a grade for the timber condition. Timber marked DRY means the wood is at a maximum moisture content of 20% and should be stored, transported and installed in a manner where this does notexceed 20%.

If you’re unsure about the grade of timber that you need, talk to the experts at Hitchcock & King — they’ll be more than happy to help.

Hitchcock & King is a leading builders merchant and timber merchant operating throughout London. For over 50 years, we’ve been supplying the nation’s capital with high-quality timber for domestic and commercial use. From hardwood prepared timber to timber carcassing and everything in between, we’re your one-stop shop for all your construction needs.

We offer same-day and next-day delivery on our products. Contact us today to place your order.