A transparent coating with long-term performance could help wood maintain its share of residential markets against material substitution and potentially expand markets in recreational property and non-residential buildings. While transparent coatings can be made reasonably resistant to UV some UV likely penetrates to the wood and by necessity clear coatings are transparent to visible light. Visible light can also cause damage over the long term thus the underlying wood needs additional protection. Four novel UV protection systems were tested as pre-treatments on uncoated wood and under three coatings, a water-based film forming coating, a water-based acrylic varnish and a solvent based water repellent. Samples were exposed to natural weathering facing South at 45° at a test site in Gulfport, Mississippi, in collaboration with the USDA Forest Products Laboratory. The test material was inspected every six months for discolouration, mold and stain, coating water repellency, flaking, erosion and cracking and substrate condition. After 24 months exposure, coatings over the combination of UV absorber and lignin stabilizer identified by Stephen Ayer were performing better than the same coatings applied over the combination recommended by Ciba and coatings over both pre-treatments were performing substantially better than controls with no pre-treatment. Projection of fitted curves beyond the data appears to indicate that pretreatment may double the life expectancy of the coating. There was no consistent effect of the synergists on either combination at this time.
Three Gram negative bacteria isolated from brownstained western hemlock were investigated for their capacity to produce hemlock brownstain. Brownstain was observed when infecting western hemlock with two bacteria. Oxygen was strongly indicated as being indespensable for the development of brownstain in infected samples. However, pH did not seem to influence the production of this stain.
Commercial and multi-family residential construction represents a growth area for the Canadian wood products industry. To capitalize on this opportunity, a thorough understanding of the necessary products and system attributes will be essential. Adequate levels of noise/sound control in multi-family buildings are mandatory requirements of building codes in Canada, the United States, Europe, and most developed Asian countries. In many jurisdictions, these requirements are as strictly enforced as those for structural sufficiency and fire safety. Much effort has been spent on evaluation of sound transmission class (STC) and impact sound insulation class (IIC) of floor and wall assemblies and on studies of flanking transmission in multi-family dwellings in Canada. However, continuing occupant complaints of poor acoustic performance in wood-frame buildings that appear to have been built according to wall and floor construction practices recommended in building codes suggest the existence of gaps in current noise control techniques.
Forintek initiated this project to investigate the relative importance of noise transmission in wood-frame residential buildings in comparison with other building serviceability issues, and to conduct a pilot study to examine construction designs of wood-frame buildings that exhibit unsatisfactory and satisfactory noise control and to identify existing gaps in current noise control techniques.
A literature review and survey of 123 occupants of wood-framed multi- and single-family residential buildings was conducted to determine the relative importance of noise transmission in comparison with other building serviceability attributes. Case studies were conducted on construction details and designs of six new wood-frame condominiums and one single family-house that were built according to code requirements and recommendations for controlling noise transmission.
We found that the general public had high expectations regarding adequate acoustic privacy. Even single- family house builders considered low sound transmission important. The multi-family building occupants ranked “sound insulation” the most “important” serviceability attribute, while single-family occupants were most concerned with “water penetration and condensation”. The lowest level of “satisfaction” was given by all respondents to “noise transmission” for their current residences, including single-family occupants, who had ranked it as not being so “important”. The case studies revealed that, current construction practices were much more effective in controlling airborne sound transmission than impact noise. The footfall noise transmission from stairs through the walls is still an unresolved issue that is not considered in the current Canadian Building Code. The low frequency footfall noise transmission between vertically-stacked units was the common complaint in some of these buildings. With no requirement for impact sound insulation in the current National Building Code of Canada, and with our existing knowledge gap concerning low frequency footfall noise transmission problems and solutions to control them, builders, acoustics consultants and design engineers have simply tended to blame wood building materials for noise-related complaints.
We concluded that if we are to satisfy the occupants of both single-and multi-family wood-frame buildings and to provide confidence for builders and design engineers in wood-frame construction with satisfactory acoustic performance, a much greater effort is needed to improve sound insulation including development of better sound insulated wood-frame systems and building materials as well as retrofitting techniques. Acoustic performance will be a critical factor for the wood products industry in gaining a greater share of the multi-family construction market and in competing with other building materials.
Canadian wood species such as spruce and pine are difficult to treat with wood preservatives or other wood enhancing formulations due to a thin sapwood band and refractory heartwood. One method of improving penetration is by biological incising. Biological incising with Dichomitus squalens was originally developed in Austria in the 1990s to increase the permeability of European spruce prior to treatment with wood preservatives. Recently the patents on this technology lapsed. It was considered unlikely that industrial use of a European white-rot fungus would be acceptable in Canada. FPInnovations therefore conducted a screening test of a range of Canadian isolates of various white-rot fungi to identify an isolate that would be suitable for biological incising of Canadian spruce and pine. Under pure culture conditions, one isolate of Dichomitus squalens isolated from white spruce was found to greatly increase the permeability of the wood, particularly in spruce. The objective of the current study was to determine if these results could be achieved on commercial sized wood under non-sterile conditions more similar to an industrial setting. Lumber samples, 3.8 cm by 8.9 cm by 400 cm in length were incubated in plastic totes with fungal inoculum. Two isolates of fungi were tested as well as two different decontamination methods (steam and Benomyl solution) and two time frames (4 and 6 weeks). Through treatment of spruce samples (19 mm penetration) with 1.7% ACQ was achieved after six weeks incubation with D. squalens 78A (a spruce isolate). In matched samples treated with MCA, a minimum of 10 mm penetration was achieved in 90% of the samples. Strength loss in some individual samples was higher than adjustment factors for conventional incising (over 25%) suggesting that incubation time may need to be shortened. Preservative penetration was more variable in pine but permeability was increased; 60% of the samples reached a minimum penetration of 5 mm. Incubation time and conditions may need to be adjusted to achieve more consistent results. The results of this study show that biological incising can greatly improve the permeability of spruce and pine and can be achieved on 38 by 89 dimension lumber under conditions that could be utilized in an industrial setting. Future work should focus on determining incubation conditions that allow penetration requirements in Canadian standards to be met with acceptable strength loss.
The biggest obstacle to the enhancement of wood properties through any form of chemical treatment is the impermeability of the heartwood of virtually all Canadian Wood species and their relatively narrow sapwood. Incisors using toothed rollers are commonplace in Canadian treating plants but they are not used for many products due to the detrimental effect on surface appearance. Alternative incising technologies anticipated to have less effects on surface appearance have been investigated over the past 30 years. This report revisits four of these technologies, lasers, needles, water jets and biological incising and evaluates their potential for further investigation based on recent advances in technology. Even using the latest technology, laser incising would be too slow and too expensive for a Canadian treating plant. Needle incising would be too slow but the equipment cost should not be an issue. Water jet treatment would also be too slow and the equipment cost is unknown. Biological incising is a very different approach involving batch processing. The major factor would be the cost of inventory which depends on the duration of incubation yet to be determined.
A major constraint to the Canadian wood preservation industry in both domestic and export markets is the difficulty of penetrating Canadian wood species with preservatives. FPInnovations has put considerable effort into various forms of improved mechanical incising but these have not been adopted by the industry due to adverse effects on throughput and appearance of the final product. Recently, work in Europe has shown promising results from biological incising using white-rot fungi that colonize wood relatively rapidly but decay slowly. The use of European isolates of fungi in North America may be constrained by phytosanitary concerns. This report covers an experiment to screen North American isolates of white-rot fungi for potential as biological control agents. A modification of the soil-block test method was used to evaluate the ability of a range of fungi to improve permeability without affecting strength properties. Wood samples were exposed to the fungi for zero, two, four and six week time increments and were then treated with a 1.5% ACQ-D solution. Preservative uptake was calculated based on change in weight before and after treatment. Two isolates of Dichomitus squalens were found that dramatically increased preservative uptake. These samples were tested for strength loss and preservative penetration. Spruce samples exposed to D. squalens isolate 78A for six weeks were completely penetrated with preservative (19 mm depth) in all six samples. D. squalens 78B also showed promising results in pine and spruce samples based on uptake and penetration data. No stiffness loss was detected in any of these samples based on results from the crushing tests.
Lack of research and design information for the seismic performance of balloon-type CLT shear walls prevents CLT from being used as an acceptable solution to resist seismic loads in balloon-type mass-timber buildings. To quantify the performance of balloon-type CLT structures subjected to lateral loads and create the research background for future code implementation of balloon-type CLT systems in CSA O86 and NBCC, FPInnovations initiated a project to determine the behaviour of balloon-type CLT construction. A series of tests on balloon-type CLT walls and connections used in these walls were conducted. Analytical models were developed based on engineering principles and basic mechanics to predict the deflection and resistance of the balloon-type CLT shear walls. This report covers the work related to development of the analytical models and the tests on balloon-type CLT walls that the models were verified against.
In 2015, the National Building Code of Canada (NBCC)  adopted prescriptive provisions to allow the construction of mid-rise (5- and 6-storey) buildings using combustible construction. These types of buildings were already permitted under the British Columbia Building Code, as of 2009 . In2014 the Province of Ontario filed an amendment to also allow mid-rise wood buildings, however, it required that the exit fire separations be built using noncombustible construction having a fire resistance rating (FRR) of not less than 1.5-hr, which was an increase from the 1-hr requirement in the NBCC. The Québec Construction Code has also filed amendments to allow mid-rise wood construction and also limits exit stairwells to use noncombustible construction.
This report addresses serviceability issues of tall wood buildings focusing on vibration and sound insulation performance. The sound insulation and vibration performance may not affect building's safety, but affects occupants' comfort and proper operation of the buildings and the funciton of sensitive equipment, consequently the acceptance of midrise and tall wood buildings in market place. Lack of data, knowledge and experience of sound and vibration performance of tall wood buildings is one of the issues related to design and construction of tall wood buildings.