Cross-Laminated Timber (CLT)

Wood Campus Timber Trade Topics are produced in collaboration with Timber Development UK and the industry technical expert on the subject, in this case, the Structural Timber Association


  • Exceptional construction speed, with most structures watertight in days
  • Exceptional carbon storage because of the volume of timber used, making carbon negative buildings possible
  • Clean and quiet construction site with no need for heavy tools
  • Relatively low site skills
  • High comfort for occupants, with good humidity control from the ‘breathable’ structure


This factsheet was correct at the time of writing but should be viewed in the context of the latest building regulations, for example Approved Document B and Amendments, which governs the use of combustible materials in taller buildings.

These can be found at


Cross-laminated timber panels are large, rigid, solid timber construction sheets used for all elements of a building’s superstructure – walls, floors and roofs.

They are made from kiln-dried, finger-jointed timber planks (typically spruce), cut into sheets and bonded under pressure in perpendicular layersCLT is an ideal material for off-site construction, with panels arriving on site machined to precise sizes, including apertures and trunking conduits

Cross-laminated Timber are Engineered Wood Products.

Timber products that have been engineered to remove natural weaknesses and enhance natural strengths. They provide stronger, longer, wider and more stable solutions than natural timber.

They deliver sustainable, low carbon structural solutions with a unique elegance, low weight and natural beauty.

Engineered Wood Products include:-

  • I Beams
  • Glulam
  • LVL (Laminated Veneered Lumber)
  • Engineered wood flooring
  • CLT (cross-laminated timber panels)

The Key Benefits

  • Stronger sections
  • Stiffer sections
  • Greater stability
  • Greater lengths and spans
  • Consistency – particularly as they are factory manufactured with lower moisture contents, a benefit when being installed in heated buildings


Cross-laminated timber (CLT) is a solid-wood construction panel made from at least three layers of lamella (pine or spruce) glued crosswise. The normal size is 3 x 16 metres, but panels are also available in a range of dimensions and grades. The CLT panels have pre-cut openings for doors and windows, according to customer requirements. CLT is suitable for both interior and exterior walls, as well as ceilings and flooring.

The product has attracted a great deal of interest. Major CLT-based building projects have both been completed and are ongoing all over the world with the aim of developing the market and demonstrating the competitiveness of the technique compared with concrete. As a product, CLT has experienced double-digit growth since it was introduced in early 2000 and this trend is expected to continue in the years to come.

Sustainable timber
Timber is the most sustainable mainstream building product. It is naturally renewable. Over 90% of timber used in UK construction comes from Europe, where more trees are grown than harvested (source: TTF Statistical Review 2016).