- For information on checking and its impact on structural performance, please refer to AITC technical note #11.
- For information on evaluating the impact of checking in the field, see AITC technical note #18.
- For “Owners Guide to Understanding Checks in Glued Laminated Timber,” see F450.
- For “Evaluation of Check Size in Glued Laminated Timber Beams,” see R475.
TECHNICAL INFORMATION
ADHESIVES
QB Corporation uses durable waterproof structural adhesives in the manufacturing process. Both PRF and Melamine adhesives are available.
Adhesives have been tested to comply with ASTM 2559, CSA, and JAS standards. For a more complete list of testing and approvals, see the attached PDF.
CHECKING
Checking is a natural phenomenon of wood that occurs when the wood dries and shrinks. The stresses built up from the shrinkage will cause a slight split. This typically is not an issue if the checking unless the checking is very severe.
QB places a great deal of attention on moisture during the manufacturing process. Our raw materials are dried to specific moisture contents, and we monitor this throughout the assembly process. Since shrinkage results from the moisture leaving the board, QB's attention will minimize any checking you may see in the beams. However, as wood is a natural material and some locations are arid climates, some checking may still occur. It is also crucial that the product be appropriately handled and stored during any inventory or installation process to minimize checking issues.
FIRE RESISTANT DESIGN
Since wood is a combustible material, many design professionals do not consider wood as part of an effective fire-resistant design. With proper design and care, wood can be used in many structures requiring fire-resistant design.
For most lightweight construction, fire resistance is provided by a covering of gypsum or other insulating materials or by fire sprinklers. This is true for wood, steel, or even concrete.
Glulam beams with proper design can accomplish fire-resistant design by using larger sections. Using wood's natural characteristics to char when exposed to high temperature and combustion. This charring develops natural insulation to fire, protecting the interior wood fiber from high temperature and flame. Of course, this charring only protects the wood for a relatively short time, just as insulation or gypsum protects other products for a short time.
The bottom line, you can protect your structure and have the desired appearance by designing your QB Corporation members for fire resistance construction. You should consult a licensed design professional in this area, although some basic information is available in the Timber Construction Manual, published by the American Institute of Timber Construction.
APA Technical Notes:
QUALITY ASSURANCE
At QB Corporation, we aim not to be average but to stand out in quality. Since our founding, we never could produce our products to the minimum acceptable standards and feel good about it. All product produced at our facility is covered under the APA-EWS quality assurance program. Rigorous independent audits ensure fabrication methods meet or exceed industry standards.
QB quality technicians work hand in hand in the plant with production personnel. They enjoy the full support of management in making quality-related decisions, and in the long run, every plant member is fully engaged in our quality program. “Quality is built in” is more than a catchphrase for us. We select quality vendors for our raw material and then carefully grade and process it into a finished product. Every piece is graded and monitored for appropriate moisture content to ensure proper gluing and curing.
Attention to detail in all aspects of the operation makes the difference between mediocre and excellent product quality. Nowhere is this attention to detail more important than in the area of finger joints. Finger joints are glued connections that make long pieces of wood out of short pieces through “fingers” cut into the ends of the boards.
These joints transfer forces from along the board to the adjoining board. It takes significant care to make a quality joint. The joint's fit, the adhesive application, and the pressure and cure are all crucial aspects of making this a critical component of beam construction work. All tension laminations are proof loaded to ensure both the lumber and the finger joint will handle the stress levels assumed for the design.
SPAN AND LOAD CHARTS
Douglas Fir/Larch Glulam PLF Charts
Beam Conversion Tables
STANDARD BEAM LAYUPS
This section aims to provide information relating to beam selection and to help avoid some common errors made in using glulam products. Most glulam beams are manufactured using one of three types of layups:
Balanced – V8
Columns – Combination 2 or V8
Unbalanced – V4
Balanced – V8
• For applications with cantilevers or multi-span applications (supported by columns or walls anywhere in mid-span).
• V4 and V8 BEAMS are surfaced on three sides, top stamped, with two bottom edges eased.
Unbalanced – V4
• Members are supported only on the ends for a simple span with no cantilevers.
• V4 and V8 BEAMS are surfaced on three sides, top stamped, with two bottom edges eased.
• Inverting a V4 Beam Reduces the Bending Design Value by 25%
Columns – Combination 2 or V8
• Combination 2 is for use as vertical columns only.
• COLUMNS are surfaced on four sides with all edges eased.
