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.
This publication characterizes nine commercial tree species of Alberta. Included are descriptions of the range and volume of each species, their wood properties, and present and potential manufacturing uses.
The objective of this project was to determine the most effective, environmentally friendly treatments which will protect value-added lumber produced from Alberta wood species from fungal discoloration. This report presents information on selected sapstain control products and the efficacy results after a four-month storage period.
Hardwood Initiative - Part 5: Development of new processes and technologies in the hardwood industry (Project 16) ; Testing the impacts of tree and stand attributes on the variability of acoustic velocity in standing trees (ST300) and logs (HM200)
Transformative Technologies Program ; Project No. TT5.15
Hardwood Initiative Project is based on two paradigms. First, the end-use potential and value of a wood product basket can be determined by the properties of its wood and should be quantified as much as possible before trees are harvested. Second, as the correlations between site conditions and wood fibre attributes can be changed by silvicultural treatments, it would be possible to optimize the wood production in terms of quantity and quality through a better understanding of silvicultural impacts on changes in wood fibre properties. This document presents the preliminary results of a research component of the project related to acoustic velocity. It focuses on testing the impacts of tree and stand attributes on the variability of non-destructive velocity (ST300 non-destructive measurement in standing tree) and of destructive velocity (HM200 destructive measurement in log). The acoustic measurements were conducted in 30 plots of sugar maple mixed with yellow birch in New Brunswick. Among the trees measured, 64 trees have been subjected to both non-destructive and destructive velocity measurement. Regression analysis by mixed model showed no significant impact of stand attributes (stand basal area and stand height) on the variation of both velocities. In addition, the defects represented by stem deformation, hole, split, wound, and stump swelling, had no significant impact on both velocities. By cons, the test showed a significant correlation between both velocities and dbh and light crown area of the tree. Non-destructive velocity was better explained by dbh and light crown than the destructive velocity. These results open the potential to produce an equation to predict the non-destructive acoustic velocity of the tree using simple tree attributes (e.g., dbh and light crown) as predictors, and to prescribe the thinning intensity for a desired level of velocity and then a desired level of wood density or stiffness.
Full title: Hardwood Initiative - Part 5: Development of new processes and technologies in the hardwood industry (Project 16) : Testing the impacts of tree and stand attributes on the variability of acoustic velocity in standing trees (ST300) and logs (HM200)
This report examines the utility of using trembling aspen, white spruce, black spruce, lodgepole pine and jack pine in typical woodworking processes. The following three processes were considered: machining (including fastener withdrawal), laminating and finishing.
An effort was made to replicate, in Alberta, a white spruce (Picea glauca (Moench.) Voss) sample obtained in British Columbia in which a spurt of rapid growth, analogous to a release event, coincided with a reduction in average wood density such that it was the lowest of 11 samples obtained in western Canada. White spruce trees were systematically sampled by 30, 40 and 50 cm diameter-at-breast height (DBH) classes from two natural stands one located near Hinton and one north of Grande Prairie. Mean ages of the tree samples were 104 and 108 years respectively. Based on eighty-one sample trees selected, site indices at breast-height age 50 were 19.3 and 18.5 respectively. Wood basic relative density was determined at breast height for each sample tree by x-ray densitometry of increment cores. Unlike previous samples obtained in Alberta, differences in mean wood density between stands were significant with values of 0.33 at Hinton and 0.35 at Grande Prairie. Mean relative density values for the 30, 40 and 50 cm DBH classes for the two samples combined were 0.36, 0.33 and 0.33 respectively compared to the species average of 0.354. ANOVA of basic relative density on DBH and stand (R2= 0.44) revealed that the effect of DBH (rate-of-growth) was significant (p = .0001). Within both stands, wood density of the 30 cm DBH class was significantly higher (a = 0.05) than that of the 40 and 50 cm DBH classes, between which wood density was not significantly different. In the Hinton sample this lack of difference between the 40 and 50 cm classes resulted from equivalent early annual growth rates. Difference in size occurred because the 50 cm trees were established about 10 years earlier. In the Grande Prairie sample growth rate in the 50 cm class was only moderately rapid. Pith-to-bark density trends were inversely related to ring width trends, consistent with previous trends observed in white spruce. A spurt of rapid growth in the Hinton sample coincided with a lower average wood density. This lends credence to similar results obtained in the earlier British Columbia sample. Foresters wanting to manage white spruce for value should consider these results when planning a thinning or overstory removal that accelerates growth rate in residual stands. The results should interest woodlands managers seeking to maximize current harvest value through more informed log allocation decisions.
The primary objective of this project was to demonstrate the feasibility of mill production of borate-treated glulam using a commercial phenol-resorcinol-formaldehyde resin and a resin modifier. The secondary objective was to demonstrate the feasibility of finger-jointing borate-treated lumber using the radio frequency heating process to produce face laminating-stock for borate-treated glulam production.
A borate-treated glulam mill trial was conducted in the glulam manufacturing facility of Western Archrib in Edmonton, Alberta on February 18-19, 2004. Good quality lodgepole pine lumber suitable for normal glulam production were selected in Western Archrib, which were borate-treated and dried at Treeline Wood Products in Edmonton, Alberta. The treated boards were then stress-graded, cut, finger-jointed, planed and face laminated in Western Archrib. The resulted finger-jointed lumber and glulam beams were sent to the Forintek western laboratory for complete testing and statistical analysis.
This project has met all its key objectives. Based on the mill trial results, the following conclusions and recommendations can be made:
a. It is feasible to produce borate-treated laminating stock using a commercial radio-frequency finger-joint process. The resulting bond quality is not affected by the borate treatment of lumber. More cases of lower strength wood failure than expected were observed in the tension tests of the finger-jointed borate-treated lumber. More study would be needed to explain this.
b. Of the 8 borate-treated glulam beams manufactured in this mill trial, only 1 beam passed the CAN/CSA-0177-M89 requirements. The data in this study indicated that the treated blue stained (and red heart stain) wood retained more water from the treating process, resulting in higher than acceptable moisture content. The laminating stock had wet pockets in stained areas after drying. When these areas were further dried after planning, the wood shrank, causing poor bonding. Therefore, moisture control of the laminating stock after treatment with aqueous borate solution is very important to the success of borate-treated glulam production. Lodgepole pine exhibiting blue stain or red heart stain is more receptive to aqueous borate treating and the post-treatment drying process should be extended beyond that for non-stained pine.
c. The mill trial data suggest that the PRF adhesive performance at 2.5% resin modifier level was strong enough to meet the requirements of CAN/CSA-0177-M89 standard. The PRF adhesive performance at 1.5% resin modifier level was potentially also good enough; however the higher resin modifier level appeared to make the adhesive more forgiving towards moisture variations.
d. If laminating stock is dried properly after borate treatment, it appears to be entirely feasible to manufacture borate-treated glulam at an average boric acid equivalence level of 2.5% (ranged from 0-8%) using an existing commercial glulam production process. The presence of many good bonds and some poor bonds indicates that the wood had not been sufficiently dried prior to use. It is likely that a retest using properly dried and conditioned wood might yield better performance and satisfy the CSA-0177-M89 laminated beam standard.