Remedial Treatment
Since remedial treatment is intended to solve a known insect or decay problem, the first thing to do is investigate the extent of the problem and, if necessary, provide temporary structural support. The investigation phase should also identify the causal factors so that these can be eliminated, where possible. Also during the investigation, the parts of the wood that have lost strength may be removed. Be aware that a wood decay fungus may have penetrated well beyond the boundaries of the visibly rotted wood. Since deterioration is underway, a rapid response is normally required. This means that where the deteriorated and infected wood cannot be removed and replaced with sound wood, the remedial treatment must be capable of rapidly penetrating the wood and killing the fungi or insects. Solids Since solids take time to dissolve and move, they are commonly supplemented by liquid treatments for more rapid eradication of the decay fungus or insect. Borate and copper/borate rods are the only solid remedial treatment method available to the homeowner. Liquids, Pastes and Gels Liquids, pastes and gels work rapidly as they do not have to rehydrate or dissolve to start moving and working. Since all visibly decayed wood should be removed wherever possible, these treatments are often used primarily to kill and contain any residual infection inadvertently left behind. Brush or spray applications are quite appropriate for this use. Gels are commonly applied to paint cracks in window joints and to the bottom of door frames, locations where moisture may get into the wood. Where decayed wood is present inside poles and timbers and cannot be removed, liquids, pastes or gels must be inserted deep into the wood for rapid action. Fumigants Gases move the most rapidly and therefore have a faster eradicant action.
Surface Pre-treatment
Liquid application: Dip diffusion treatment of green (wet) lumber Dip-diffusion treatment involves immersion of freshly cut lumber, still wet from the tree, in a concentrated solution of preservative. The preservative may be thickened to increase the amount of solution retained on the surface. The lumber is stacked, covered and stored for periods of weeks to allow the preservative to diffuse deep into the wood. In New Zealand, framing lumber has been treated with borates using this process since the 1950s. Dip-diffusion works well with wood species that are mostly sapwood or have wet heartwood. The ratio of the surface area to the volume, the amount of solution retained on the surface, and the solubility of the preservative limit the amount of chemical that can be delivered deep into the wood using this process. For example, a boric acid loading of 0.5% by weight of the wood, sufficient to prevent decay and beetle attack, can be applied to nominal 2 inch lumber using this process. However, a boric acid loading of 2.0% by weight, sufficient to prevent attack by Formosan termites, cannot be achieved without multiple dips and months of storage. Liquid application: Spray treatment of framing Since this type of treatment is typically done during the construction phase, it can be applied to the whole structure or to selected parts of the structure that are anticipated to be at risk from fungal decay or insect attack. Solids and fumigants are not appropriate for these applications, and the only widely used formulations are based on borates. Because the wood is dry at this stage, and because borates require moisture for diffusion, it helps if such treatments are formulated to improve penetration in dry wood. This is usually achieved by adding glycols. Nevertheless, the initial preservative penetration cannot be expected to be as good as that provided by a pressure treatment process. Spray applications of borate are becoming popular in certain regions of the USA as part of termite management systems. Typically, whole house superficial treatments are used to protect against drywood termites and wood boring beetles. This replaces regular fumigation. For subterranean termite protection, concentrated glycol borates may be applied to the bottom two feet of all wood in contact with the slab or, for crawl space construction, two feet up and inwards from the foundation. This replaces a soil barrier. Brush Application Brush applications for surface pre-treatment are basically limited to field-cut preservatives for pressure treated wood and homeowner treatment of structures, presumably with limited life expectancy. Copper naphthenate works well above ground or in ground contact, but its dark green colour (fading to brown after a year or so) is not very appealing. Zinc naphthenate is colourless and can be tinted to suit, but does not work as well in ground contact. Borates are typically used for field cuts on interior sill plates. In addition, borate/glycol mixtures are available for domestic use.
Depot Treatment
Since depot treatment is localized, it is critical that it be placed in the right location, which requires an understanding of how moisture may get into the structure. This can only be done when construction is complete or very near completion. At that point the degree of protection by design can be assessed and any water traps can be identified and, where possible, eliminated. The treatment can then be applied in the right location to intercept moisture close to its point of entry. Depot treatments are an excellent choice for a few common design applications such as partially exposed beams. When a beam penetrates the building envelope, only a portion is exposed to moisture and it makes sense to just treat that part. Depot treatments are especially useful for products that are not well-suited to pressure treatment with waterborne preservatives, like glulam. Similarly, depot treatments are appropriate for exposed log ends in log homes – logs that extend beyond the protective roof overhang are at risk of decay. Solids Depot treatments most commonly use a solid form of preservative. Borate, copper/borate and fluoride rods are highly suited to this end use since they are easy to install and the active ingredients only become mobile if moisture entry occurs. Other formats Pastes can be packed into drilled holes or routed grooves – log home grooves are an appropriate application. Liquid injection is less common, as this involves drilling small holes, inserting a pin nozzle injector connected to a 70 -120 psi tank/pump, and forcing preservative along the grain under pressure. A series of such holes is required, particularly for large dimensions, to increase loading. Less suited to depot treatments, fumigants have not, to our knowledge, been used in these applications.
Supplemental Treatment
Supplementary treatment may be added wherever on-site cutting or drilling of wood is unavoidable, or where it is suspected the original protection measures may be inadequate. This is most commonly done in applications such as wood foundations, agricultural buildings, or non-residential long-life applications such as utility poles and bridge timbers. For wood foundations and agricultural buildings, it is normal to expect some end cutting and boring for bolts, pipes or electrical wiring. Typically copper naphthenate is brushed on the cut ends or holes in the treated wood to protect the exposed surfaces. Experience has shown that this is adequate for the limited exposure resulting from such cases. For cases such as poles or bridge timbers, the original preservative protection can be lost over time due to degradation or depletion of the active ingredients. A need for supplementary treatment may be indicated by damage to similar structures in the same area. Or there may be evidence that the risk of damage has increased, for example, if new termites move into the area. In cases like utility poles, where these are part of the physical infrastructure of an organization, inspection, maintenance and remediation are regularly practiced to ensure continued safety in use and to schedule replacement. Often the cost of supplementary treatment is relatively small compared to the cost of inspection, and is a very small fraction of the cost of premature failure. Supplementary treatment may also be prudent in terms of due diligence (reducing legal liability). During inspection of these structures, drills or increment borers may be used to determine the condition of the interior of the wood members. It is advised to treat these holes, to avoid infection from non-sterilized drills and borers. In addition, as holes are typically drilled where decay is suspected or anticipated, treating the holes is wise to supplement protection at that site. Solids Borate, copper/borate and fluoride rods have seen increasingly widespread use as supplementary treatments for internal decay due to their convenience in handling and very low toxicity. Copper moves more slowly in the wood than borate, providing protection to the zone around the rod if the borate is removed over time through mass flow of water. This is mainly of concern for utility poles in wet climates, where moisture moves into the pole from the soil, wicks up the pole and evaporates above ground, moving the borate up the pole with it – this leaves the borate in a part of the pole not especially at risk for decay. The rate of water flow may be relatively slow in Douglas fir (an impermeable wood species) treated with an oil-borne preservative having some water repellency. It may be more rapid in southern pine (a very permeable wood species) treated with a waterborne preservative. Liquids, Pastes and Gels Spray and foam application of liquids and gels are increasingly used for supplementary treatment of wood frame buildings against termites and wood boring beetles. Holes are drilled into each stud space and the liquids or gels are pumped in under pressure. Coverage cannot be expected to be as effective as that achieved by spray treatment during construction. Liquids can be poured or pumped into drilled holes to treat internal decay in utility poles or timbers. Typically the loading of preservative that can be achieved is limited in the first case by the size and location of the holes and the solubility of the chemical, and in the second case by the permeability of the wood. Another approach is to leave a pressurized device attached to the pole below ground, which pushes a larger amount of liquid into the pole over a longer time period. Care must be taken to ensure that drilled holes do not intersect voids or checks leading to the surface of the wood; otherwise, the liquids can flow out. Pastes can be packed into drilled holes to treat internal decay. Alternatively, they can be brushed or trowelled on or applied on bandages to treat external decay. Fumigants Fumigant treatments have been used successfully for decades on utility poles and timber structures. The gas moves rapidly through the wood, adsorbing to the lignocellulose and providing several years of residual protection.
Fasteners
Fasteners, Connectors and Flashing for Wood Treated With Copper-Based Preservatives The presence of moisture is a precondition for corrosion of metals. Treated wood is typically used in applications where it may be exposed to moisture for considerable periods so any fasteners and connectors used with treated wood must also be resistant to these conditions. In addition, most wood preservatives designed for exterior use contain copper that may react with the metals used to fabricate fasteners and connectors therefore, it is important to use the right type of fastener and/or connectors. Where treated wood is used in dry environments to prevent damage by wood-destroying insects, including termites, corrosion is of less concern. Users and specifiers should also be aware that corrosive industrial, or salt air, environments may also require the use of appropriate corrosion resistant metals. Types of Wood Preserving Treatments Most copper-based preservatives are corrosive to unprotected fasteners and connectors. More recent systems such as MCA where the copper isn’t introduced in an ionic salt form, are designed to reduce the corrosion of metals, and the preserved wood is approved for use in contact with aluminum (e.g. brackets or outdoor furniture legs). Borate treatments do not increase the risk of corrosion. Recommendations on Connectors for Treated Wood Connectors used for wood treated with a copper-based preservative must be manufactured from steel either hot–dipped galvanized in accordance with ASTM A653 or hot dipped galvanized after manufacture in accordance with ASTM A123. Galvanizing nails and screws is actually a sacrificial coating to protect the structural integrity of the fastener, and the presence of some white corrosion product on the surface is normal. Red rust appearing is an indicator of coating failure. The service life of these components can be extended by using a barrier membrane between the connector and the treated wood surface. Stainless steel connectors (type 304 or 316) should be used for maximum service life, for high preservative retentions (i.e. ground contact products) or severe applications such as salt spray environments. For borate-treated wood used inside buildings, the same connectors can be used as for untreated wood. Recommendations on Fasteners for Treated Wood Fasteners for use in treated wood that will be exposed to the weather should be selected to withstand weathering as long as the treated wood itself. As a minimum, nails for wood treated with a copper-based preservative must be hot-dipped galvanized in accordance with ASTM A153. Hot-dipped galvanized nails should not be fastened using a high pressure nail gun due to the risk of damage to the coating during firing. The protective coating on electroplated galvanized fasteners is too thin and will perform poorly, and common nails will corrode rapidly after fastening most copper-based treated wood. Stainless steel should be used for maximum service life, for high preservative retentions or severe applications such as salt spray environments. Where appropriate, copper fasteners may also be used. Fasteners used in combination with metal connectors must be the same type of metal to avoid galvanic corrosion caused by dissimilar metals. For example stainless steel fasteners should not be used in combination with galvanized connectors. Screws intended for use on wood treated with a copper-based preservative must be hot dipped galvanized in accordance with ASTM A153 or, if recommended by the manufacturer and the preservative supplier, high-quality polymer coated. Stainless steel should be used for maximum service life, for high preservative retentions or severe applications such as salt spray environments. For borate treated wood used inside buildings, the same fasteners can be used as for untreated wood. As a general rule aluminum fasteners should not be used with treated wood, except new generation products (MCA treated) specifically tested, approved and labelled as suitable for contact with Aluminum. Recommendations on Flashing for Treated Wood Flashing used in contact with treated wood must be compatible with the treated wood and be last long enough to be suitable for the intended application. Flashing must also be of the same type of metal as any fasteners that penetrate through them to avoid galvanic corrosion. Copper and stainless steel are the most durable metals for flashing. Galvanized steel, in accordance with ASTM A653, G185 designation, is also suitable for use as flashing. Other Fasteners, Connectors or Hardware as Recommended by the Manufacturer There may be additional products such as polymer or ceramic coatings for fasteners, or vinyl or plastic flashings that are suitable for use with treated wood products. Consult the individual fastener, connector or flashing manufacturer for recommendations for use of their products with treated wood. Current Recommendations for Drying and Conditioning of Treated Wood Prior to Construction. Wood treated with copper-based preservatives should be at the least surface dried at the treating plant, in the store or at the job site before attachment of fasteners, connectors, flashing or other hardware. A moisture meter with a calibration for preservative treated wood should be used to verify that the wood is within a similar moisture content range to untreated construction lumber (i.e. about 12 to 18%) otherwise the treated wood can undergo similar shrinkage related cracking and deformation as incorrectly conditioned untreated lumber. Canadian Preservation Industry Canada has had a wood preservation industry for more than 100 years. Canada is tied with the UK as the world’s second largest producer of treated wood (the USA is first, by a large margin). In 1999, the most recent year for which we have data, Canada produced 3.5 million cubic metres of treated wood. There are about 60 treating plants in Canada. As with most other industrialized countries, Canada developed a wood preservation industry using creosote, initially to service railroads (the ties holding the rails) and then utilities (power poles). Creosote production began declining by the 1950s, and by the 1970s was being somewhat replaced for these traditional uses by pentachlorophenol. Today, these oil-borne preservatives only constitute 17% of Canadian treated wood production. The remaining 83% of production uses water-borne preservatives such as CCA, ACQ, CA and MCA. The industry began its substantial shift to the water borne
Treatability
Treatability of Major North American Softwoods Some wood is easier to treat than others. The particular structure of the cells for a given piece of wood will determine how permeable the wood is to chemicals. This table describes the permeability of common softwoods used in North America. The permeability ratings are: 1 – Permeable 2 – Moderately Impermeable 3 – Impermeable 4 – Extremely Impermeable Tree Permeability Permeability Predominant in the Tree Sapwood Heartwood Douglas Fir 2 4 Heartwood Western Hemlock 2 3 Heartwood Eastern Hemlock 2 4 Heartwood White Spruce 2 3-4 Heartwood Engelmann Spruce 2 3-4 Heartwood Black Spruce 2 4 Heartwood Red Spruce 2 4 Heartwood Sitka Spruce 2 3 Heartwood Lodgepole Pine 1 3-4 Heartwood Jack Pine 1 3 Heartwood Red Pine 1 3 Sapwood Southern Pine 1 3 Sapwood Ponderosa Pine 1 3 Sapwood Amabilis Fir (Pacific silver fir) 2 2-3 Heartwood Alpine Fir 2 3 Heartwood Balsam Fir 2 4 Heartwood Western Red Cedar 2 3-4 Heartwood Eastern White Cedar 2 3-4 Heartwood Yellow Cypress 1 3 Heartwood Western S-P-F 2 3-4 Heartwood Eastern S-P-F 2 4 Heartwood Hem-Fir 2 3 Heartwood Western Larch 2 4 Heartwood Tamarack 2 4 Heartwood Incising We can improve the penetration of preservative into impermeable wood by making little cuts in the wood. A series of small, shallow slits are cut into the wood by an incising machine. This is an effective way of increasing the treatability of lumber pieces which are predominantly heartwood. Species with heartwood permeability ratings of higher than 3 require high density incising (over 7,500 incisions per square meter). Incising does reduce the strength of lumber and this effect must be taken into account in engineering calculations. Drying to Maximise Treatabilty Unless the purchaser can be assured that lumber for treatment will be air dried to less than 30% moisture content, the specification of KD lumber for preservative treatment is strongly recommended. The problem with treating lumber which is not kiln dried is that the practicalities of production and delivery lead to the potential for poor product quality. The durability of treated Canadian lumber relies on a shell of preservative treatment preventing access by wood-rotting fungi to the untreated core. If the treated shell fails to prevent penetration by checks or abrasion or if the wood-rotting fungus is already in the untreated core, premature failure can result. There are four major pitfalls in treating green lumber: saturated sapwood, frozen lumber, check development and pre-treatment infection. Saturated Sapwood In order for the preservative to penetrate the wood cells, they must be empty of water, that is, the wood must be below 30% moisture content. In green lumber the sapwood cells may be too full of sap to accept any preservative. The sapwood is the part most susceptible to decay and most in need of preservative penetration. Partial air or kiln drying to between 20 and 30% moisture content is ideal, but there is seldom the time or the conditions necessary to do this. Purchasing commercial KD material (maximum 20%) is normally the only option to ensure the sapwood will accept treatment. Frozen Lumber The overwhelming majority of production is treated over the winter to prepare for the spring and summer outdoor construction season. With the exception of coastal British Columbia, most regions of Canada will be dealing with frozen wood at this time. Many treating plants do not have dry kilns, thus material is treated in the condition it is delivered to the plant. Preservative will not penetrate through ice until it is fully thawed. This typically occurs in contact with the treating solution. Frozen green lumber contains a lot of ice and there is insufficient time for this to thaw during typical commercial treating cycles. The residual moisture (12 – 20%) in kiln-dried lumber is in the cell walls and will not impede preservative penetration even if it is frozen. Check Development Checks only develop when the moisture content of wood drops below about 28%. If lumber is treated green and then dries, checks will penetrate the treated zone exposing the untreated core. If lumber is kiln-dried to the in-service moisture content, typically around 16% in exterior exposure, the checks will be largely developed prior to treatment. This means that the checks will be lined with a treated zone and the shell of treatment will remain intact. Pre-treatment Infection A lesser problem than the above three, but still of some concern, is the potential for survival through the manufacturing process of wood-rotting fungi that may have infected in the tree, log or lumber storage stages. At worst, this might only apply to 10% or fewer of pieces. Nevertheless, we have seen examples where treatment of green lumber without application of heat (60°C or more) fails to kill wood-rotting fungi already in the product, leading to premature failure in service. This can occur in as little as 4 years. CCA treatment is a cool process, but most kiln-drying schedules will kill all wood-rotting fungi.
Resilience
Individuals in the design and construction community are increasingly choosing materials, design techniques and construction procedures that improve a structure’s ability to withstand and recover from extreme events such as intense rain, snow and wind, hurricanes, earthquakes and wildfire. As a result, specifying robust materials and design details, and constructing flexible and easily repairable buildings are becoming important design criteria. Resilience is the ability to prepare and plan for, absorb, recover from, and more successfully adapt to adverse events. For a building, this means being designed to withstand and recover quickly from adverse situations such as flooding and high winds, with an acceptable level of functionality. A structure built to withstand such natural disasters with minimal damage is easier to repair and can contribute to sustainable development. Designing for resilience can contribute to minimizing human risk, reducing material waste and lowering restoration costs. As a result of shifting weather patterns due to climate change, there is a growing interest in adaptation and designing for resilience. Higher temperatures can increase the odds of more extreme weather events, including severe heat waves and regional changes in floods, droughts and potential for more severe wildfires. There are more intense and more frequent hurricanes, and precipitation often comes in the form of intense single-day events. Warmer winter temperatures cause water to evaporate in the air and if the temperature is still below freezing, this can lead to unusually heavy snow, sleet or freezing rain, even in years when snowfall is lower than average. A resilient building is able to deal with changes such as a heavier snow load, wider temperature fluctuations, and more extreme wind and rain. Existing wood buildings can be easily adapted or retrofitted if there is a need for increased wind or snow loading. Wood buildings that are properly designed and constructed perform well in all types of climates, even the wettest. Wood tolerates high humidity and can absorb or release water vapour without compromising the structural integrity. In some regions, climate change is seen to be contributing to increasingly complex wildfire seasons, which results in greater risk of extreme wildfire events. Some wildland fire regulations target specific construction features in wildland-urban interface areas, such as exterior decks, roof coverings, and cladding. A number of wood products meet these regulations for various applications, including heavy timber elements, fire retardant treated wood and some wood species that demonstrate low flame spread ratings (less than 75). For further information, refer to the following resources: Resilient and Adaptive Design Using Wood (Canadian Wood Council) American Wood Council American Institute of Architects
Tall Wood Buildings
A tall wood building is a building over six-storeys in height (top floor is higher than 18 m above grade) that utilizes mass timber elements as a functional component of its structural support system. With advanced construction technologies and modern mass timber products such as glued-laminated timber (glulam), cross-laminated timber (CLT) and structural composite lumber (SCL), building tall with wood is not only achievable but already underway – with completed contemporary buildings in Canada, US, Australia, Austria, Switzerland, Germany, Norway, Sweden, Italy and the United Kingdom at seven-storeys and taller. Tall wood buildings incorporate modern fire suppression and protection systems, along with new technologies for acoustic and thermal performance. Tall wood buildings are commonly employed for residential, commercial and institutional occupancies. Mass timber offers advantages such as improved dimensional stability and better fire performance during construction and occupancy. These new products are also prefabricated and offer tremendous opportunities to improve the speed of erection and quality of construction. Some significant advantages of tall wood buildings include: the ability to build higher in areas of poor soils, as the super structure and foundations are lighter compared to other building materials; quieter to build on site, which means neighbours are less likely to complain and workers are not exposed to high levels of noise; worker safety during construction can be improved with the ability to work off large mass timber floor plates; prefabricated components manufactured to tight tolerances can reduce the duration of construction; tight tolerances in the building structure and building envelope coupled with energy modelling can produce buildings with high operational energy performance, increased air tightness, better indoor air quality and improved human comfort Design criteria for tall wood buildings that should be considered include: an integrated design, approvals and construction strategy, differential shrinkage between dissimilar materials, acoustic performance, behaviour under wind and seismic loads, fire performance (e.g., encapsulating the mass timber elements using gypsum), durability, and construction sequencing to reduce the exposure of wood to the elements. It is important to ensure early involvement by a mass timber supplier that can provide design assistance services that can further reduce manufacturing costs through the optimization of the entire building system and not just individual elements. Even small contributions, in connection designs for example, can make a difference to the speed of erection and overall cost. In addition, mechanical and electrical trades should be invited in a design-assist role at the outset of the project. This allows for a more complete virtual model, additional prefabrication opportunities and quicker installation. Recent case studies of modern tall wood buildings in Canada and around the world showcase the fact that wood is a viable solution for attaining a safe, cost-effective and high-performance tall building. For more information, refer to the following case studies and references: Brock Commons Tall Wood House (Canadian Wood Council) Origine Point-aux-Lievres Ecocondos,Quebec City (Cecobois) Wood Innovation and Design Centre (Canadian Wood Council) Technical Guide for the Design and Construction of Tall Wood Buildings in Canada (FPInnovations) Ontario’s Tall Wood Building Reference (Ministry of Natural Resources and Forestry & Ministry of Municipal Affairs) Summary Report: Survey of International Tall Wood Buildings (Forestry Innovation Investment & Binational Softwood Lumber Council) www.thinkwood.com/building-better/taller-buildings
Durability – FAQ
Please refer to the pdf documents below for Frequently Asked Questions pertaining to durability: General Wood Decay and repair Discolouration Finishing Mould Treated Wood
Controlling Termites
Fortunately for Canada, most of this country lies north of the limit for termites on the North American continent. However, because termites and people both prefer the warmer parts of this country, 20% of Canada’s population live in areas where termites are present. Long winters limit termite activity in the wild, but the warmth provided by our buildings seems to encourage more serious problems in urban environments. Damage caused by the Eastern subterranean termite, (Reticulitermes flavipes Kollar), has reached economically important levels in areas of Toronto and other cities in Southern Ontario. There are some suggestions that the Western subterranean termite, (Reticulitermes hesperus Banks), may be causing significant damage in the Okanagan region of British Columbia. Termites are a much more serious threat in many of our export markets such as the Southeastern USA, Japan and Southeast Asia. While termite control measures appropriate to each region are specified in local and regional building codes, an overview of such measures may be of use to Canadian marketers of wood products and manufactured homes. Termite control measures can be broadly grouped into six categories: Suppression Site Management Soil Barrier Slab/foundation details Structural durability Surveillance and Remediation Click Here for more details on the 6 strategies More Information Termite Control and Wood-Frame Buildings– 11-page illustrated bulletin from CWC, further covering the 6-point integrated strategy discussed. Includes photos of termite control products. Integrated Control of Subterranean Termites: The 6S Approach. This 20-page Forintek paper introduces and thoroughly discusses the 6-point integrated strategy. Includes very specific design and maintenance advice. Termite Map of North America Combatting Termites – very short and simple summary fact sheet from Forintek.
Applying Treatment
Click Here for more information of field treatment Holes drilled to apply depot, supplementary or remedial treatments should be on vertical surfaces or undersides, where possible, to avoid creating additional routes for moisture entry. In the case of supplementary treatment, cut ends should be placed so they are not in ground contact where possible. Holes for treatment should not be drilled below ground level if it can possibly be avoided. All holes should be closed with a tight-fitting plug. Ideally this should be removable to allow re-treatment. Holes for water-soluble treatments should be placed in the right locations to intercept moisture close to its points of entry. Look carefully at the structure and think about moisture sources, water traps, moisture entry points, moisture flow and signs of moisture entry. Moisture sources include direct rainfall, diverted rainfall (via windows, cladding, balcony and walkway surfaces, roof overhangs, flashing, parapets, eavestroughs and downspouts), rain penetration of moisture barriers via nail holes, splits, failure of joints or deterioration of caulking, rain splash, blowing snow, ice dams, condensation, concrete foundations, soil contact, irrigation systems, drain and plumbing leaks. Water traps include metal “shoes”, V joints, checks, appressed boards, cupped horizontal surfaces and anywhere a rim is created at the edge of a horizontal surface. Accumulation of dirt and debris often indicates a water trap. Growth of algae also indicates locations where moisture hangs around longer after rain. Moisture entry points include all locations with end grain, around nails, screws and bolts plus any other holes or penetrations, checks and delaminations. Moisture flow in wood may be 100 to 1000 times faster along than across the grain. Patterns of moisture distribution in wood are therefore commonly elongated cones or lens shapes centred on the point of entry. Signs of moisture entry include swelling, darker colouration, fungal stain, iron stain around fasteners, nail popping and flaking of film-forming surface finishes. Confirmation of moisture contents conducive to decay can be made using electrical-resistance type moisture meters. Capacitance-type moisture meters may also be useful, but these can give erroneous results in the area of metal fittings.
Effective R Calculator
La raison d’être de cet outil en ligne et calculateur est de fournir aux concepteurs des solutions normatives et conformes aux exigences nationales en matière d’efficacité énergétique pour les assemblages muraux. Cet outil est conçu pour donner suffisamment d’information aux architectes, aux concepteurs, aux ingénieurs, aux consultants et aux contractants pour qu’ils soient en mesure de déterminer rapidement et en toute confiance quels assemblages muraux conviennent à chaque zone climatique au Canada. Bien que le but premier soit d’assurer la conformité aux modifications de décembre 2012 au Code national du bâtiment de 2010 (CNB) pour les maisons et au Code national de l’énergie pour les bâtiments de 2011 (CNEB) pour les bâtiments plus importants, les assemblages muraux deviendront une référence pratique en matière de conformité à tout code du bâtiment qui laisse les concepteurs choisir une valeur R effective. Veuillez noter que le calcul de la résistance thermique effective a été réalisé conformément au paragraphe 9.36.5. de la division B du CNB. This online tool contains the following sections: List of Available Wall Assemblies How to Use the Effective R Calculator Canadian Code Requirements for Above Grade Wall Thermal Design Understanding the Builder Notes Wall Thermal Design Performance Literature: Excerpts from the CHBA Manual Understanding the Building Science Durability Notes ACKNOWLEDGEMENTS Many thanks to the steering committee and project team for making this online tool possible: Steering Committee Alejandra Nieto ROCKWOOL Ben Hawken Mattamy Homes Limited BJ Yeh APA – The Engineered Wood Association Bob Wilson R.S. Wilson Building Inspection & Consulting Inc. Bruce West City of Brampton Christopher McLellan Natural Resources Canada Cory McCambridge APA – The Engineered Wood Association Dave Henderson Brookfield Homes David Silburn SAIT Green Building Technologies Gillian Haley ERA Architects Inc. Jason Shapardanis Empire Communities Jieying Wang FPInnovations John Hockman JLHockman Consulting Inc. Kelsey Saunders Sustainable.TO Louis Previte Great Gulf Homes Paul Smith Mattamy Homes Corporation Peter Birkbeck Icynene Inc. Peter Culyer EIFS Council of Canada Richard Kadulski Solplan Review Rick Gratton Brookfield Residencial Properties Inc. Rick Roos Roxul Inc. Robert Marshall CertainTeed SAINT-GOBAIN Salvatore Ciarlo Owens Corning Canada Silvio Plescia Canada Mortgage and Housing Corporation Steve Doty Empire Communities Todd Rogers City of St. Catharines To join the committee or to discuss inclusion of more products in the tool, please contact Robert Jonkman – rjonkman@cwc.ca Project Team Project Initiator Robert Jonkman Canadian Wood Council Project Lead Michael Lio buildABILITY Corportation Project Manager and Publishing Expert Magdalena Krawczyk buildABILITY Corporation Builder Lead and Field Expert Andy Oding Building Knowledge Canada Technical Lead and Building Science Expert Chris Timusk Timusk Consulting, George Brown College Technical Project Advisor Gord Cooke Building Knowledge Canada WUFI Expert Panelist Graham Finch RDH Consulting WUFI Expert Panelist Chris Schumacher RDH Consulting
