A study was conducted with the primary objective of gathering information for the development of a protocol for evaluating the surface quality of cross-laminated timber (CLT) products. The secondary objectives were to examine the effect of moisture content (MC) reduction on the development of surface checks and gaps, and find ways of minimizing the checking problems in CLT panels. The wood materials used for the CLT samples were rough-sawn Select grade Hem-Fir boards 25 x 152 mm (1 x 6 inches). Polyurethane was the adhesive used. The development of checks and gaps were evaluated after drying at two temperature levels at ambient relative humidity (RH).
The checks and gaps, as a result of drying to 6% to 10% MC from an initial MC of 13%, occurred randomly depending upon the characteristics of the wood and the manner in which the outer laminas were laid up in the panel. Suggestions are made for minimizing checking and gap problems in CLT panels. The checks and gaps close when the panels are exposed to higher humidity.
Guidelines were proposed for the development of a protocol for classifying CLT panels into appearance grades in terms of the severity of checks and gaps. The grades can be based on the estimated dimensions of the checks and gaps, their frequency, and the number of laminas in which they appear.
The purpose of this research is to investigate what differences, if any, exist between the modeled energy consumption and building envelope performance of the Wood Innovation Research Laboratory (WIRL) building following eight months of in-situ data collection. The WIRL building was completed in July of 2018 by the University of Northern British Columbia (UNBC) and is located in Prince George, British Columbia. Built in partnership with the Province of British Columbia, the building was designed to meet Passive House standards, a building certification system that requires the building to have low energy input requirements due to high levels of thermal insulation and minimal air leakage. To ensure the building achieves the established energy use targets set forth under the Passive House certification system, a computer model of the proposed building design must be completed prior to the start of construction using the Passive House Planning Package (PHPP) software. Inputs to the model include envelope design, mechanical energy use, building location and airtightness value. Key outputs included the predicted annual heating demand (kWh/m2a), total primary energy demand (kWh/m2a), and air tightness of the building envelope (ACH@50Pa). Based on the final building design model and test results achieved following completion, the WIRL building was deemed to have met all Passive House requirements and certification was achieved. To complete on-going data collection of the in-situ performance of the WIRL building, temperature and humidity sensors were installed in two of the exterior wall assemblies and the building’s floor. In addition, gas and electrical energy use meters were installed to monitor the building’s energy consumption. The installation of all equipment was made possible by Forest Innovation Investment through their 2018/2019 Wood First Program.