History of CLT
This “next-generation” of engineered wood products, which has been extensively tested and widely used in Europe for the past 20 years, has limitless applications for construction, industrial matting, bridging and beyond. Anything that is built with wood, steel, concrete, or masonry can be built with CLT! Because of CLT’s amazing strength, rigidity and stability, it is a cost-competitive replacement for the traditional structural materials like steel, concrete, and masonry. Cross Laminated Timber is a multi-layer, solid wood panel, typically, consisting of three to nine layers of lumber. Kiln-dried boards are first finger jointed together to form continuous boards up to 40 feet long. These boards are then micro-planed to exacting dimensions and assembled layer by layer, with each layer placed perpendicular to the previous layer. After each assembled layer is placed, the entire surface is faced-glued using an advanced, non-toxic, and formaldehyde–free adhesive. Next, this massive assembly of boards is pressed and bonded under immense vertical and horizontal hydraulic pressure to form a panel of wood up to 12 feet wide, 40 feet long and over 12 inches deep. Finally, the panels are then sized and fabricated to specific design specs with our state-of-the-art CNC machine. Cross lamination improves the structural properties of the panels by distributing along-the-grain strength of the wood in both directions, while the perpendicular cross lamination bond negates any significant shrinkage or deformation of the panels. As demand continues to grow for efficient, cost-effective and sustainable building materials, innovative design, engineering, and construction professionals are increasingly turning to Cross Laminated Timber for projects of all sizes. CLT offers the structural simplicity needed for a wide variety of projects, as well as benefits such as design versatility, rapid installation, reduced waste, lighter weights and energy efficiency.
THE HISTORY OF CLT
Cross-laminated timber was developed in Austria in the early 1990s. It has been popular in Europe for more than 20 years, with extensive research and a documented track record supporting its widespread use. In the early 2000’s construction with CLT increased dramatically in Europe, partially driven by the green building movement as well as code changes and improved marketing and distribution channels. There are hundreds of impressive buildings built around the world using CLT that show the many advantages this product can offer to the construction sector. In North America, CLT is relatively new but is quickly gaining momentum. SmartLam is the first and only Cross Laminated Timber manufacturer in the United States. The use of CLT is gaining interest here in the residential, commercial, and high-rise construction sectors. Driving the demand for architectural CLT in North America as a building material is the need to provide a lighter, low carbon, renewable, and sustainable building material to architects, engineers, developers, and contractors. Last year, the American National Standards Association approved ANSI/APA PRG 320-2012 Standard for Performance-Rated Cross-Laminated Timber, a product standard that details manufacturing and performance requirements for qualification and quality assurance. CLT was also recently included in the 2015 International Building Code (IBC). Up until now and in areas that have not yet adopted the 2015 IBC, several innovative architects and designers have already specified and built CLT structures in the U.S. and Canada, having had them approved under their local building code as an alternative building system.
Manufacturing Process of CLT
A Cross Laminated Timber panel consists of several layers of kiln-dried lumber boards stacked in alternating directions, bonded with structural adhesives, and pressed to form a solid, straight, rectangular panel. CLT panels typically consist of an odd number of layers (usually, three to seven or more). This cross lamination provides dimensional stability, strength and rigidity, which makes CLT a viable alternative to conventional framing, concrete, masonry and steel in many applications. It can be used for an entire building, as both the lateral and vertical load resisting system, or for select elements such as the roof, floors or walls. CLT as a structural panel element is also used as a superior industrial matting, bridging and retaining wall product that replaces heavy timbers, steel, and concrete.
Lumber Selection We use Douglas Fir, Western Larch & SPF Grade 2 and Better.
Lumber Drying The boards are kiln dried to a moisture content of 12% +/- 3%. Proper moisture content provides for proper adhesion and prevents dimensional variations and surface cracking.
Defects According to the strength and final visual quality, defects such as large knots and resin or bark pockets are removed.
Finger Jointing The boards are trimmed and finger jointed to obtain the desired lengths and quality of lumber. SmartLam can produce solid wood panels up to 41’ long. Our new plant will be capable of producing panels 12′ wide and 64′ long.
Panel Assembly Panels are assembled by placing the finger-jointed boards side-by-side (to achieve the desired length & width) to form solid wood layers. Each succeeding layer is laid perpendicular to the preceding layer.
Adhesive & Press Each layer is sprayed with adhesive and the entire “sandwich” of layers is then pressed vertically and horizontally in a large hydraulic press. Our adhesives are waterproof and fire-resistant polyurethane; solvent-free and formaldehyde-free.
Fabrication Assembled panels are cut to size, milled to spec, and finished as required by our Hundegger CNC Panel Fabricator. This 4 head/5 axis CNC Fabricator is capable of milling nearly any design specification.