So I’m going to strip it all back – excuse the pun – and break engineered timber down to its most simple self.
Engineered timber is basically a timber sandwich with structural capabilities akin to concrete in its material strength. It has a bi-axial structure (two-axis) that allows for design flexibility and architectural innovation.
The two-axis come from taking solid panels of kiln-dried, finger jointed approved timber planks and stacking them at right angles, then glueing under pressure. This bonds the timber in perpendicular layers. Incidentally, the glue is an adhesive-free of solvents and formaldehyde by reputable manufacturers so there is no risk of toxic emissions at any stage in the products life cycle.
The “depth” of the sandwich depends on the purpose (wall, floor or roof elements) and can be manufactured in 3, 5 7 or more board layers. The boards can also be supplied with one of three different grades of top layer – non-visual, industrial grade visual and exposed grade visual (basically a scale of level of finish based on the aesthetics required).
Once the panels are manufactured they are cut to exact design requirements of the project using CNC technologies. As you’ll know, traditional openings in buildings need to be measured on site. With CNC cutting, the need to account for site tolerances is all but eliminated.
The result of this process is a timber sandwich, weighing a fifth the weight of its concrete equivalent but with the same structural properties as pre-cast concrete panels. Strong and lightweight – but what about the big question, cost.
As with any project, the cost equation needs to be assessed based on the individual requirements of the site and the building. We’ve found that engineered timber is fast to install (allows shorter programmes of work and less labour on site) and, in some situations the weight/strength equation, is translating into cost-effective foundation solutions, replacing the need for expensive concrete piling foundations. So generally CLT has potential to be cost neutral and often with cost savings when able to achieve economies of scale such as for 6 or more floors of construction.
Engineered timber has so many benefits (I’ve listed some of them below for those who like extra for experts). It really could become, as Alex de Rijk said, “the new Concrete”.
EXTRA FOR EXPERTS – THE OTHER BENEFITS
- Lightweight but strong
- Can be used for structural and non-structural elements of a building or alongside structural steel and other materials in a hybrid design (budget permitting)
- Fast to install and requiring less labour on site to do so
- Quieter construction site, less wastage
- Highly predictable in fire (the outer layer initially burns but builds up a layer of insulating char, providing 30 to 60 or more minutes of fire resistance, dependent on the thickness of the panel.)
- The insulation R-values the insulation performance of timber at 0.13 W/m*K is encouraging (but consider the full composite external walling design)
- It works wonderfully well when creating airtight, moisture controlled designs
- The natural timber finish can be an alternative to GIB linings as finish.