About Co2 Larch ®

Co2 Larch <sup>®</sup> about
Siberian Larch is a straight grained timber with few knots and good durability/resistance to insects making it an ideal timber for cladding, fencing, decking and flooring. We only sell Unsorted I – 3 A/B Grade***, which is the highest grade available in regards to quality and look. It is known as unsorted and consists of the highest three appearance qualities i.e – I-2 & 3.

A Grade

Co2 Larch® A Grade - Has small tight knots and is suitable for all our products.

Additional Information

Siberian Larch can be left untreated or treated with a suitable exterior product. (Please see Our Accessories page)

Have a durability class 3 rating* (BS EN 350-2 classes), and is incredibly hard, Janka Scale** of Hardness of 1,100 lbf (4,900 N). It is the only conifer that is classed within the hardwood group of timbers, and is compatible in hardness to oak (Janka Scale** English Oak 1,120 lbf (4,980 N)).


When selecting your timber type for your project it is worth taking in to consideration BS EN 350 timber durability class.

Durability is the ability of a species to resist decay either naturally or through preservatives. The Class is based on the ability of the heartwood (inner part of the tree) to resist fungal decay. The sapwood (the living outermost portion of the tree)is considered not durable and should not be used for external projects without preservative.

BS EN 350 has 5 classes of durability they are:-
Class 1 to 3 can be left as untreated timber, a natural ageing process will accrue e.g. most timbers will turn a grey colour. Class 4 and 5 will need to be treated with preservatives.

For further information see www.greenspec.co.uk/building-design/cladding-durability-quality

**Janka Scale Explained

The Janka Scale is very useful in directly determining how well a wood will withstand dents and dings. Furthermore it can be useful as an quick indication of how difficult a specific timber is to nail screw, sand or saw.

The number listed is the amount of pounds-force (lbf) or newtons (N) required to embed a 11.28 mm diameter steel ball into the wood to 50% of the ball’s diameter.

***Quality Grades According to BS 1186-3

BS 1186-3 has 3 grades applicable to external timber cladding, mostly concerned about the size and frequency of knots::-

For further information see www.greenspec.co.uk/building-design/cladding-durability-quality