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Know Your Types of Timber & Terminology

Wood and timber are still commonly used in many applications in the construction and landscaping businesses. If you’re planning a project that will involve the use of timber, you may be unsure which kinds are best for different jobs, while it can also be easy to get confused by some of the terminology associated with timber and joinery.

In this article, we’ll be taking a look at some of the different types of timber that are commonly used in construction, along with a brief guide to key terminology used in the business.

Types of Timber

Timber used in the building trade breaks down into three main categories: hardwood, softwood and CLS – let’s take a brief look at each of these in turn:


  • Hardwood

As the name suggests, hardwood is stronger than softwood. It is usually sourced from deciduous trees with broad leaves that grow slowly, which makes it a more expensive choice, although that is balanced out by the fact that it’s far more durable.

Common types of hardwood used in the building trade include:

  • Meranti – one of the most common of the hardwoods used in the building trade, often used for things like flooring, doors and skirting boards
  • Ash – another common hardwood often used in construction and furniture making. Not ideal for outdoor use as it won’t last long when in contact with the ground 
  • European Oak – the ‘king of trees’ isn’t just one of the toughest and most durable woods around, it’s also one of the most attractive and is highly resistant to both fungal attack and shrinkage. Often used for doors, windows and structural or architectural joinery


  • Softwood

Usually sourced from coniferous trees, softwood is lighter and more flexible than hardwood. And because it grows quicker, it’s also usually cheaper and more easily replaced, making it more environmentally friendly as an option as well. 

Some of the more common types of softwood include:

  • Spruce – Sitka spruce is planted in more UK forests than any other tree. It is more durable and has a higher resistance to decay than many other softwoods, making it suitable for many uses in construction. Also widely used for fencing and making pallets
  • European Redwood – this is essentially the same as Scots Pine, but is the name given to the imported version as opposed to that which is homegrown. A good all-round timber often used in both interior and exterior joinery. Also commonly used for decking
  • Larch – also a member of the pine family, larch timber is tough, durable and waterproof. Often used for exterior cladding and interior panelling. It’s also fairly resistant to rot, making it a popular choice for use in fencing and fence posts


  • CLS (Canadian Lumber Standard)

Despite its name, Canadian Lumber Standard (CLS) is rarely sourced from Canada. It’s not a type of timber in its own right, as it is usually made from spruce, fir or pine, but occasionally also cedar or hemlock. It will have been kiln-dried, treated and planed ready for use. It’s also free of large knots around the edge of the wood, making it more resistant to fire. As long as it has been correctly treated, it’s ideal for outdoor use, and is often used for timber frame construction, carcassing and internal stud walls.


Timber Terminology

  • C16 and C24 timber – softwoods are graded according to their strength; although C24 is the stronger, C16 is the more commonly used in the UK. 
  • Durability – timber is graded from 1 (very durable, e.g. teak) through to 5 (not durable, e.g. birch and beech) 
  • Moisture content – timber for indoor use will generally have a moisture content of between 8% and 14%; timber for outdoor use will have a moisture content of between 12% and 18%
  • Nominal and actual size – although wood is now sold in metric measurements, it is usually still referred to in imperial measurement terms. So, for example, a piece of wood that used to be two by four inches and that used to be known as ‘2×4’ is still referred to as that (nominal size) but is now nearer 1.5″ x 3.5″ (actual size)
  • Rough sawn timber – timber that has been cut into planks, but which hasn’t been treated or kiln-dried


At Neil Sullivan & Sons, we’re a leading supplier of all kinds of products used in the construction business, including ready-mix and volumetric concrete and a wide variety of aggregates. We also supply timber products, including top-quality railway sleepers ideal for lots of exciting garden landscaping projects.

Contact us now to find out more.