Environmental product declarations (EPDs) – Copy
EPD Link An Industry Average EPD for Canadian Pre-fabricated Wood I-Joists • View Resource A Regionalized Industry Average EPD for Canadian Softwood Lumber • View Resource A Regionalized Industry Average EPD for Canadian Oriented Strand Board • View Resource An Industry Average EPD for Canadian Softwood Plywood • View Resource A Regionalized Industry Average EPD for Canadian Wood Trusses • View Resource Stakeholders within the building design and construction community are increasingly being asked to include information in their decision-making processes that take into consideration potential environmental impacts. These stakeholders and interested parties expect unbiased product information that is consistent with current best practices and based on objective scientific analysis. In the future, building product purchasing decisions will likely require the type of environmental information provided by environmental product declarations (EPDs). In addition, green building rating systems, including LEED®, Green Globes™ and BREEAM®, recognize the value of EPDs for the assessment of potential environmental impacts of building products. EPDs are concise, standardized, and third-party verified reports that describe the environmental performance of a product or a service. EPDs are able to identify and quantify the potential environmental impacts of a product or service throughout the various stages of its life cycle (resource extraction or harvest, processing, manufacturing, transportation, use, and end-of-life). EPDs, also known as Type III environmental product declarations, provide quantified environmental data using predetermined parameters that are based on internationally standardized approaches. EPDs for building products can help architects, designers, specifiers, and other purchasers better understand a product’s potential environmental impacts and sustainability attributes. An EPD is a disclosure by a company or industry to make public the environmental data related to one or more of its products. EPDs are intended to help purchasers better understand a product’s environmental attributes in order for specifiers to make more informed decisions selecting products. The function of EPDs are somewhat analogous to nutrition labels on food packaging; their purpose is to clearly communicate, to the user, environmental data about products in a standardized format. EPDs are information carriers that are intended to be a simple and user-friendly mechanism to disclose potential environmental impact information about a product within the marketplace. EPDs do not rank products or compare products to baselines or benchmarks. An EPD does not indicate whether or not certain environmental performance criteria have been met and does not address social and economic impacts of construction products. Data reported in an EPD is collected using life cycle assessment (LCA), an internationally standardized scientific methodology. LCAs involve compiling an inventory of relevant energy and material inputs and environmental releases, and evaluating their potential impacts. It is also possible for EPDs to convey additional environmental information about a product that is outside the scope of LCA. EPDs are primarily intended for business-to-business communication, although they can also be used for business-to-consumer communication. EPDs are developed based on the results of a life cycle assessment (LCA) study and must be compliant with the relevant product category rules (PCR), which are developed by a registered program operator. The PCR establishes the specific rules, requirements and guidelines for conducting an LCA and developing an EPD for one or more product categories. The North American wood products industry has developed several industry wide EPDs, applicable to all the wood product manufacturers located across North America. These industry wide EPDs have obtained third-party verification from the Underwriters Laboratories Environment (ULE), an independent certification body. North American wood product EPDs provide industry average data for the following environmental metrics: Global warming potential; Acidification potential; Eutrophication potential; Ozone depletion potential; Smog potential; Primary energy consumption; Material resources consumption; and Non-hazardous waste generation. Industry wide EPDs for wood products are business-to-business EPDs, covering a cradle-to-gate scope; from raw material harvest until the finished product is ready to leave the manufacturing facility. Due to the multitude of uses for wood products, the potential environmental impacts related to the delivery of the product to the customer, the use of the product, and the eventual end-of-life processes are excluded from the analysis. For further information, refer to the following resources: ISO 21930 Sustainability in buildings and civil engineering works – Core rules for environmental product declarations of construction products and services ISO 14025 Environmental labels and declarations – Type III environmental declarations – Principles and procedures ISO/TS 14027 Environmental labels and declarations – Development of product category rules ISO 14040 Environmental management – Life cycle assessment – Principles and framework ISO 14044 Environmental management – Life cycle assessment – Requirements and guidelines American Wood Council Canada Green Building Council Green Globes BREEAM® Annual Review Rules and Form EPD
Treatment during engineered wood product manufacture
Some engineered wood panel products, such as plywood and laminated veneer lumber (LVL) are able to be treated after manufacture with preservative solutions, whereas thin strand based products (OSB, OSL) and small particulate and fibre-based panels (particleboard, MDF) are not. The preservatives must be added to the wood elements before they are bonded together, either as a spray on, mist or powder. Products such as OSB are manufactured from small, thin strands of wood. Powdered preservatives can be mixed in with the strands and resins during the blending process just prior to mat forming and pressing. Zinc borate is commonly used in this application. By adding preservatives to the manufacturing process it’s possible to obtain uniform treatment throughout the thickness of the product. In North America, plywood is normally protected against decay and termites by pressure treatment processes. However, in other parts of the world insecticides are often formulated with adhesives to protect plywood against termites.
Durability
Throughout history, wherever wood has been available as a resource, it has found favour as a building material for its durability, strength, cost-competitiveness, ease-of-use, sustainability, and beauty. Wood-frame and timber buildings have an established record of long-term durability. From the ancient temples of China and Japan built in the 1000s, and the great stave churches of Norway to the numerous North American buildings built in the 1800s, wood construction has proven it can stand the test of time. Although wood building technology has been changing over time, wood’s natural durability properties will continue to make it the material of choice. This website helps designers, construction professionals, and building owners understand what durability hazards exist for wood, and describes durability solutions that ensure wood, as a building material, will perform well for decades, and even centuries, to come. Durability Guidelines Wood structures, properly designed and properly treated, will last indefinitely. This section includes guidance on specific applications of structures that have constant exposure to the elements. Mass timber exteriors Modern Mass Timber Construction includes building systems otherwise known as post-and-beam, or heavy-timber, and cross laminated timber (CLT). Typical components include solid sawn timbers, glue-laminated timbers (glulam), parallel strand lumber (PSL) laminated veneer lumber (LVL) laminated strand (LSL), and CLT. Heavy-timber post and beam with infill walls of various materials is one of the oldest construction systems known to man. Historic examples still standing range from Europe through Asia to the long-houses of the Pacific Coastal first nations. Ancient temples in Japan and China dating back thousands of years are basically heavy timber construction with some components semi-exposed to the weather. Heavy-timber-frame warehouses with masonry walls dating back 100 years or more are still serviceable and sought-after as residences or office buildings in cities like Toronto, Montreal and Vancouver (Koo 2013). Besides their historic value, these old warehouses offer visually impressive wood structures, open plan floors and resultant flexibility of use and repurposing. Building on this legacy, modern mass timber construction is becoming increasingly popular in parts of Canada and the USA for non-residential construction, recreational properties and even multi-unit residential buildings. Owners and architects typically see a need to express these structural materials, particularly glulam, on the exterior of the building where they are at semi-exposed to the elements. In addition wood components are being increasingly used to soften the exterior look of non-wood buildings and make them more appealing. They are anticipated to remain structurally sound and visually appealing for the service life. However, putting wood outside creates a risk of deterioration that needs to be managed. Similar to wood used for landscaping, the major challenges to wood in these situations are decay, weathering and black-stain fungi. This document provides assistance to architects and specifiers in making the right decisions to maximize the durability and minimize maintenance requirements for glulam and other mass timber on the outside of residential and non-residential buildings. It focusses on general principles, rather than providing detailed recommendations. This is primarily focussed on a Canadian and secondarily on a North American audience. Click here to read more Disaster Relief Housing Shelter needs after natural disasters come in three phases: Immediate shelter: normally supplied by tarpaulins or light tentsTransition shelter: may be heavy-duty tents or more robust medium-term shelters.Permanent buildings: Ultimately permanent shelters need to be constructed when the local economy recovers. Immediate and transition shelters are typically supplied by aid agencies. Light wood frame is ideal for rapid provision of medium- to long-term shelter after natural disasters. However, there are challenges in certain climates for wood frame construction that must be addressed in order to sustainably and responsibly build them. For example, many of the regions which experience hurricanes, earthquakes and tsunamis also have severe decay and termite hazards including aggressive Coptotermes species and drywood termites. In extreme northern climates, high occupancy loads are common and when combined with the need for substantial thermal insulation to ensure comfortable indoor temperatures, can result in condensation and mould growth if wall and roof systems are not carefully designed. The desire of aid organizations to maximize the number of shelters delivered tends to drive down the allowable cost dictating simplified designs with fewer moisture management features. It may also be difficult to control the quality of construction in some regions. Once built, “temporary” structures are commonly used for much longer than their design life. Occupier improvements over the longer term can potentially increase moisture and termite problems. All of these factors mean that the wood used needs to be durable. One method of achieving more durable wood products is by treating the wood to prevent decay and insect/termite attack. However, commonly available preservative treated wood in Canada may not be suitable for use in other countries. Selection of the preservative and treatment process must take into account the regulations in both the exporting and receiving countries, including consideration of the potential for human contact with the preserved wood, where the product will be within the building design, the treatability of wood species, and the local decay and termite hazard. Simple design features, such as ensuring wood does not come into contact with the ground and is protected from rain, can reduce moisture and termite problems. Building with concrete and steel does not eliminate termite problems. Termites will happily forage in a concrete or masonry block buildings looking for wood components, furniture, cupboards, and other cellulosic materials, such as the paper on drywall, cardboard boxes, books etc. Mud tubes running 10ft over concrete foundations to reach cellulosic building materials have been documented. Indeed, termites have caused major economic damage to cellulosic building materials even in concrete and steel high-rises in Florida and in southern China. Timber bridges Timber bridges are an excellent way to showcase the strength and durability of wood structures, even under harsh conditions, when material selection, design, construction and maintenance are done well. They could also be critical infrastructure elements that span fast rivers or deep gorges. Consequences of failure of these structures can be severe
Buildings
Wall Types for Water Control Building envelope experts generally speak of three or four different approaches to design of a wall for moisture control. Face seal walls are designed to achieve water tightness and air tightness at the face of the cladding. An example would be stucco applied directly to sheathing or masonry without a moisture barrier membrane such as building paper. Joints in the cladding and interfaces with other wall components are sealed to provide continuity. The exterior face of the cladding is the primary – and only – drainage path. There is no moisture control redundancy, i.e., there is no back-up system. A face seal system must be constructed and maintained in perfect condition to effectively control rain water intrusion. In general, these walls are only recommended in low risk situations, such as wall areas under deep overhangs or in dry climates. Concealed barrier walls are designed with an acceptance that some water may pass beyond the surface of the cladding. These walls incorporate a drainage plane within the wall assembly, as a second line of defense against rain water. The face of the cladding remains the primary drainage path, but secondary drainage is accomplished within the wall. This drainage plane consists of a membrane such as building paper, which carries water down and out of the wall assembly. An example is siding or stucco applied over building paper. Concealed barrier walls are appropriate in areas of low to moderate exposure to rain and wind. Rainscreen walls take water management one step further by incorporating a cavity between the back of the cladding and the building paper. This airspace ventilates the back of the cladding, helping it to dry out. The cavity also acts as a capillary break between cladding and building paper, thereby keeping most water from making contact with the building paper. An example of a rainscreen wall is stucco or siding applied to vertical strapping over the building paper. Rainscreen walls are appropriate in high rain and wind exposures. An advancement of the rainscreen technology is the pressure-equalized rainscreen. These walls use vents to equalize the pressure between the exterior and the cavity air, thereby removing one of the driving forces for water penetration (when it is pushed through cracks due to high pressure on the face of the wall and low pressure in the cavity). These walls are for very high risk exposures. Importance of an Overhang In a rainy climate, an overhang is one of the simplest and most effective ways to reduce the risk of water intrusion. An overhang is an umbrella for the wall, and the deeper the better. A survey of leaky buildings in British Columbia commissioned by Canada Mortgage and Housing Corporation in 1996 showed a strong inverse correlation between depth of overhang and percent of walls with problems. However, even a small overhang can help protect the wall, largely due to its effect on driving rain. One important benefit of overhangs and peaked roofs often not appreciated is the effect of these elements on wind pressure. Wind-driven rain is typically the largest source of moisture for walls. An overhang and/or sloped roof will help direct the wind up and over the building, which reduces the pressure on the wall and thereby reduces the force of the driving rain striking the wall. This means water is less likely to be pushed by wind through cracks in the wall. Minimize the Holes Most rainwater problems are due to water leaking into the wall through holes. If care isn’t taken to protect discontinuities in the envelope, water can leak around window framing and dryer vents, at intersections like balconies and parapets, and at building paper joints, for example. Good design detailing and careful construction is critical! So is maintenance of short-life sealants like caulk around window frames. BC Housing-Homeowner Protection Office has updated the “Best Practice Guide for Wood-Frame Envelopes in the Coastal Climate of British Columbia” originally developed by Canada Mortgage and Housing Corporation and published “Building Enclosure Design Guide for Wood-Frame Multi-Unit Residential Buildings” with extensive information on design and construction detailing. Use our Effective R calculator to determine not only the thermal resistance of walls, but also a durability assessment of the wall based on representative climate conditions across Canada. Related Publications For on-line design and construction tips, try the following:The Build a Better Home program, operated by APA-The Engineered Wood Association, runs training courses, operates a demonstration houses, and offers publications. The web site offers construction information and provides links to all relevant APA publications. Building Enclosure Design Guide: Wood-Frame Multi-Unit Residential Buildings.
Bâtiments
Types de murs permettant de contrôler l’eau En règle générale, les experts en enveloppes de bâtiment considèrent qu’il existe trois ou quatre approches différentes pour la conception de murs au profit du contrôle de l’humidité. Les murs avec barrière d’étanchéité en surface sont conçus de façon à obtenir une étanchéité à l’eau et à l’air à la surface du parement. Un exemple de ceci serait le stuc appliqué directement sur le revêtement ou la maçonnerie, sans membrane d’étanchéité comme le papier de construction. Les joints entre le parement et les interfaces, et les autres composants, sont scellés afin d’assurer la continuité. La face extérieure du parement est la principale et unique voie d’évacuation de l’eau. Il n’y a pas de renfort pour le contrôle de l’humidité, c.-à-d. qu’il n’y a pas de système complémentaire. Un système d’étanchéisation en surface doit être construit et maintenu en parfaite condition afin de contrôler efficacement l’infiltration de l’eau de pluie. En général, ces murs sont recommandés uniquement dans les situations où les risques sont faibles, comme les zones murales situées sous de larges avant-toits ou là où le climat est sec. Les murs dotés d’une membrane dissimulée sont conçus dans la perspective où il est possible qu’un peu d’eau s’infiltre au-delà de la surface du parement. L’intérieur de ces murs comporte un dispositif d’évacuation de l’eau, en guise de deuxième ligne de défense contre l’eau de pluie. La face du parement reste la voie d’évacuation principale, mais une évacuation secondaire est exécutée à l’intérieur du mur. Le dispositif de drainage se compose d’une membrane comme du papier de construction, qui achemine l’eau jusqu’en bas et à l’extérieur du mur. Un bardage ou du stuc appliqué sur du papier de construction constitue un exemple d’un tel dispositif. Les murs comptant une membrane dissimulée sont appropriés aux endroits modérément exposés à la pluie et au vent. Les murs à écran pare-pluie vont un pas plus loin dans le contrôle de l’eau, en incorporant une cavité entre le dos du parement et le papier de construction. Le vide d’air ventile le dos du parement et l’aide à s’assécher. De plus, la cavité fait office de coupure capillaire entre le parement et le papier de construction, empêchant ainsi la majeure partie de l’eau d’entrer en contact avec le papier. Un mur avec stuc ou parement appliqué sur la fourrure verticale par-dessus le papier de construction constitue un bon exemple de mur à écran pare-pluie. De tels murs conviennent à des bâtiments fortement exposés à la pluie et au vent. L’écran pare-pluie à pression équilibrée constitue l’un des progrès de la technologie des écrans pare-pluie. Ces murs font appel à des orifices pour équilibrer la pression entre l’air extérieur et celui de la cavité, éliminant ainsi l’une des forces favorisant la pénétration de l’eau (lorsque celle-ci est poussée au travers des fissures en raison de la pression élevée à la surface du mur et de la pression basse dans la cavité). Ces murs sont réservés aux endroits où les risques d’exposition sont très élevés. Importance des avant-toits Lorsque le climat est pluvieux, un avant-toit constitue l’un des moyens les plus simples et efficaces de réduire le risque d’infiltration de l’eau. Un avant-toit peut être comparé à un parapluie pour les murs, et plus il est large, mieux c’est. Une étude sur les bâtiments aux prises avec des problèmes de fuites en Colombie-Britannique, demandée par la Société canadienne d’hypothèques et de logement en 1996, a démontré la forte corrélation inverse entre la largeur d’un avant-toit et le pourcentage de murs problématiques. Par contre, même un avant-toit étroit peut aider à protéger le mur, en grande partie en raison de son effet sur la pluie battante. L’un des avantages importants mésestimés des avant-toits et des toits à double pente est leur effet sur la pression du vent. En règle générale, la pluie poussée par le vent est la plus grande source d’humidité dans les murs. Un avant-toit ou une toiture inclinée aidera à rediriger le vent vers le haut et par-dessus le bâtiment, réduisant ainsi la pression sur le mur et, par conséquent, force de la pluie battante qui martèle le mur. L’eau sera donc moins susceptible d’être poussée par le vent dans les fissures du mur. Minimiser les orifices La grande majorité des problèmes causés par l’eau pluviale est attribuable à l’eau qui s’infiltre par les trous des murs. Si aucune mesure n’est prise pour remédier aux irrégularités de l’enveloppe, l’eau pourra s’infiltrer par exemple autour des cadrages de fenêtres et du conduit d’évacuation de la sécheuse, aux intersections comme les balcons et les parapets, et aux joints du papier de construction. Une conception détaillée et une construction soigneuse sont donc essentielles! Tout comme l’est l’entretien des éléments d’étanchéité de courte durée, comme le mastic de calfeutrage autour des cadrages de fenêtres. Le BC Housing-Homeowner Protection Office a mis à jour le « Best Practice Guide for Wood-Frame Envelopes in the Coastal Climate of British Columbia », initialement conçu par la Société canadienne d’hypothèques et de logement, et a publié le « Building Enclosure Design Guide for Wood-Frame Multi-Unit Residential Buildings », qui comprend des renseignements exhaustifs sur la conception et la construction. Utilisez notre calculatrice de résistance effective non seulement pour établir la résistance thermique des murs, mais également pour procéder à une évaluation de leur durabilité en fonction des conditions climatiques représentatives à l’échelle du Canada. Publications associées Pour obtenir des conseils en ligne sur la conception et la construction, consultez ce qui suit : Le programme « Build a Better Home », dirigé par l’APA – The Engineered Wood Association, anime des cours de formation, présente des maisons témoins et offre des publications. Le site Web fournit des renseignements sur la construction, de même que des liens vers toutes les publications pertinentes de l’APA. Building Enclosure Design Guide Guide: Wood-Frame Multi-Unit Residential Buildings.
Environmental Issues
Safe Handling Using common sense and standard safety equipment (personal protection and wood-working machinery) applies when working with any building products. Gloves, dust masks and goggles are appropriate for use with all woodworking. Here are a few key points specific to treated wood: Pressure-treated wood is not a pesticide, and it is not a hazardous product. In most municipalities, you may dispose of treated wood by ordinary garbage collection. However, you should check with your local regulations. Never burn treated wood because toxic chemicals may be produced as part of the smoke and ashes. If preservatives or sawdust accumulate on clothes, launder before reuse. Wash your work clothes separately from other household clothing. Treated wood used for patios, decks and walkways should be free of surface preservative residues. Treated wood should not be used for compost heaps where free organic acids produced early in the composting process can remove the fixed chemicals. It is, however, safe to use for growing vegetables in raised soil beds. If, after reading this, you are still concerned, place a layer of plastic sheet between the soil and the treated wood wall. Treated wood should not be cleaned with harsh reducing agents since these can also remove the fixed chemicals. Environmental Concerns All wood preservatives used in the U.S. and Canada are registered and regularly re-examined for safety by the U.S. Environmental Protection Agency and Health Canada’s Pest Management and Regulatory Agency, respectively. Wood preservation is not an exact science, due to the biological – and therefore variable and unpredictable – nature of both wood and the organisms that destroy it. Wood scientists are trying to understand more about how wood decays to ensure that durability is achieved through smart design and construction choices where possible, so that as a society we can be selective in our use of preservatives. Comparing treated wood to alternative products A series of life cycle assessments has been completed comparing preservative treated wood to alternative products. In most cases, the treated wood products had lower environmental impacts. Click for consumer safety information on handling treated wood (Canada). Read More
Treated Wood
When you want to use wood that is not naturally decay resistant in a wet application (outdoors, for example) or where it may be at risk for insect attack, you need to specify preservative-treated wood. This is lumber that has been chemically treated to make it unattractive to fungi and other pests. In the same way that you would specify galvanized steel where it would be at risk of rusting, you specify treated wood where it will be used in a setting conducive to decay. Wood does not deteriorate just because it gets wet. When wood breaks down, it is because an organism is eating it as food. Preservatives work by making the food source inedible to these organisms. Properly preservative-treated wood can have 5 to 10 times the service life of untreated wood. This extension of life saves the equivalent of 12.5% of Canada’s annual log harvest. Preserved wood is used most often for railroad ties, utility poles, marine piles, decks, fences and other outdoor applications. Various treatment methods and types of chemicals are available, depending on the attributes required in the particular application and the level of protection needed.
Environmental product declarations (EPDs)
EPD Link An Industry Average EPD for Canadian Pre-fabricated Wood I-Joists A Regionalized Industry Average EPD for Canadian Softwood Lumber A Regionalized Industry Average EPD for Canadian Oriented Strand Board An Industry Average EPD for Canadian Softwood Plywood A Regionalized Industry Average EPD for Canadian Wood Trusses Stakeholders within the building design and construction community are increasingly being asked to include information in their decision-making processes that take into consideration potential environmental impacts. These stakeholders and interested parties expect unbiased product information that is consistent with current best practices and based on objective scientific analysis. In the future, building product purchasing decisions will likely require the type of environmental information provided by environmental product declarations (EPDs). In addition, green building rating systems, including LEED®, Green Globes™ and BREEAM®, recognize the value of EPDs for the assessment of potential environmental impacts of building products. EPDs are concise, standardized, and third-party verified reports that describe the environmental performance of a product or a service. EPDs are able to identify and quantify the potential environmental impacts of a product or service throughout the various stages of its life cycle (resource extraction or harvest, processing, manufacturing, transportation, use, and end-of-life). EPDs, also known as Type III environmental product declarations, provide quantified environmental data using predetermined parameters that are based on internationally standardized approaches. EPDs for building products can help architects, designers, specifiers, and other purchasers better understand a product’s potential environmental impacts and sustainability attributes. An EPD is a disclosure by a company or industry to make public the environmental data related to one or more of its products. EPDs are intended to help purchasers better understand a product’s environmental attributes in order for specifiers to make more informed decisions selecting products. The function of EPDs are somewhat analogous to nutrition labels on food packaging; their purpose is to clearly communicate, to the user, environmental data about products in a standardized format. EPDs are information carriers that are intended to be a simple and user-friendly mechanism to disclose potential environmental impact information about a product within the marketplace. EPDs do not rank products or compare products to baselines or benchmarks. An EPD does not indicate whether or not certain environmental performance criteria have been met and does not address social and economic impacts of construction products. Data reported in an EPD is collected using life cycle assessment (LCA), an internationally standardized scientific methodology. LCAs involve compiling an inventory of relevant energy and material inputs and environmental releases, and evaluating their potential impacts. It is also possible for EPDs to convey additional environmental information about a product that is outside the scope of LCA. EPDs are primarily intended for business-to-business communication, although they can also be used for business-to-consumer communication. EPDs are developed based on the results of a life cycle assessment (LCA) study and must be compliant with the relevant product category rules (PCR), which are developed by a registered program operator. The PCR establishes the specific rules, requirements and guidelines for conducting an LCA and developing an EPD for one or more product categories. The North American wood products industry has developed several industry wide EPDs, applicable to all the wood product manufacturers located across North America. These industry wide EPDs have obtained third-party verification from the Underwriters Laboratories Environment (ULE), an independent certification body. North American wood product EPDs provide industry average data for the following environmental metrics: Global warming potential; Acidification potential; Eutrophication potential; Ozone depletion potential; Smog potential; Primary energy consumption; Material resources consumption; and Non-hazardous waste generation. Industry wide EPDs for wood products are business-to-business EPDs, covering a cradle-to-gate scope; from raw material harvest until the finished product is ready to leave the manufacturing facility. Due to the multitude of uses for wood products, the potential environmental impacts related to the delivery of the product to the customer, the use of the product, and the eventual end-of-life processes are excluded from the analysis. For further information, refer to the following resources: ISO 21930 Sustainability in buildings and civil engineering works – Core rules for environmental product declarations of construction products and services ISO 14025 Environmental labels and declarations – Type III environmental declarations – Principles and procedures ISO/TS 14027 Environmental labels and declarations – Development of product category rules ISO 14040 Environmental management – Life cycle assessment – Principles and framework ISO 14044 Environmental management – Life cycle assessment – Requirements and guidelines American Wood Council Canada Green Building Council Green Globes BREEAM® Annual Review Rules and Form EPD
Finishing Quick Tips
For new wood, remember: The wood must be dry. Drying time depends on a few factors. Ideally the wood should be kiln-dried (stamped “S-DRY”, “KD” or “KDAT”, see glossary of “dry lumber”). If the wood is surface wet from rain or washing, let dry 1 to 2 days. If the wood is wet through (green lumber, pressure-treated lumber not stamped “KDAT”), 2 days of drying is acceptable if using a “damp-friendly” coating. Otherwise: The wood must be allowed to thoroughly dry to a stable outdoor moisture content; about 15% in most climates. The characteristics of the wood and the climatic characteristics of its environment are so variable that drying time is hard to predict. The common way to determine wood moisture content is with a moisture meter. (Note: specific correction factors should be applied if a moisture meter is used on preservative-treated wood.) Weather conditions during coating application can affect the coating’s drying, appearance and performance. Follow the coating manufacturer’s recommendation. Coat as soon as possible after the wood has been planed or sanded. Apply finishes within two weeks of exposure, or sooner if possible (Surface Preparation for Fresh Wood). Otherwise, follow the instructions for aged (weathered) wood below. If the wood is very smooth, lightly sand it to roughen the surface with 100-120 grit sand paper. This greatly improves the coating bond. Brush free of dirt and sawdust. If painting the wood, apply a primer coat. Use an extractive-blocking primer, if needed (for example, with western red cedar or redwood) over the entire piece, or a knot sealing primer if needed (Special Considerations). When dry, apply two coats of top quality paint. For stains and water repellents, follow the instructions on the can regarding number of coats. Carefully follow the instructions on the can regarding best environmental conditions for coating, application recommendations, safety precautions and clean-up. For aged (weathered) wood, remember: For wood that has been previously coated, please read about refinishing. Clean the wood and remove discolourations such as iron stain, if desired. Expose fresh wood because coatings perform best when applied to freshly exposed wood surfaces. Allow to dry. See Surface Preparation for Aged Wood. Brush free of dirt and sawdust, and proceed with application of the coating. When maintaining or refinishing, remember: Avoid the need to refinish by keeping an eye on the coating and adding a fresh coat before the previous coat wears away, cracks or peels. This may be as frequent as every six months with water repellents, every year or two with stains, and every few years with paint (See Maintenance). Spot-treat worn areas to extend the period between full applications of a fresh coat. Sand away any failed coating and any weathered wood, and re-apply the coating (See Maintenance). If the coating has failed on a large scale, or the coating is getting too thick for refinishing, or if a change in type of coating is desired, completely strip away the old coating – please read about refinishing.
Glossary
Acrylic A type of water-borne coating product containing acrylic polymers. Alkyd A type of polyester resin. Term often used to signify solvent-borne coatings, e.g., oil paints. Backpriming The application of a finish coat to the back side of wood such as shingles or siding. Binder The non-volatile film-forming solid portion in a coating, which binds the pigment particles together after the film is dry and creates the bond with the substrate. Typical binders include alkyd resins, acrylic resins and polyurethane resins. Bleeding When the colour of a discolouration or other material works up through a coating to the surface. Commonly used to describe leaching of tannins in extractive species like western red cedar and redwood (typically happens for the first year or so if not stain blocked). Blistering When a coating forms bubbles due to air, water vapour or solvent under the film. Dry lumber Lumber which has been dried to a moisture content of 19% or less. Any 4” and thinner boards or dimension lumber surfaced at a moisture content (MC) of 19% or less may be stamped “S-DRY” and stamped “KD” if kiln-dried to a maximum moisture content of 19%. Lumber in the USA may be stamped “KDAT” if kiln-dried after pressure treatment with preservatives. Enamel Generic term for an alkyd-based pigmented coating that dries to a smooth, hard, glossy finish. The term is often more broadly used for a coating which gives a hard, stain-resistant film. Extractives Soluble chemicals particularly present in the heartwood of some species which provide the wood with resistance to decay and insects. Fungicide A substance which inhibits the growth of fungus. Often added to coatings to protect the coatings themselves from fungal growth. Latex Term used to signify water-borne paints. Lacquer Coating material characterized by rapid evaporation of the solvent to produce a thin, hard film. Linseed oil Obtained by crushing flax seeds, this natural oil can be used as a vehicle in paints, as a softening agent for the resins in varnishes, or can be used alone as a wood finish material. Raw linseed oil is a food source for fungi and must be boiled to destroy these nutrients. Most “boiled” linseed oil is not boiled but contains metallic dryers and biocides. Oil-based paints Paints using natural oils such as linseed or tung oil as the binder, with turpentine as the usual solvent. The term is now usually used to refer to paints with both alkyds and oil as the binders, and with a carrier of mineral spirits or other solvents. Paint An opaque coating generally made with a binder, liquids, additives and pigments. Applied in liquid form, it dries to form a continuous film that protects and improves the appearance of the substrate. Pigment Finely ground solids that impart colour, hiding power (opacity) and ultraviolet protection. Pitch Also called resin, this sticky substance is a mixture of rosin and turpentine and is found in most softwoods but particularly the pines, spruces and Douglas-fir. Can ooze from the pitch pockets and sometimes the knots for a year or two if not set by kiln-drying. Resin can bleed through finishes and will harden into beads, but this can be cleaned up with mineral spirits and will stop eventually. Primer The first complete coat of paint applied in a painting system. Many primers are designed to enhance adhesion between the surface and subsequent topcoats. Most primers contain some pigment, some lend uniformity to the topcoat, some inhibit corrosion of the substrate, and some stop the discolouration of the topcoat. Resin For tree resin, see Pitch. In coatings, see Binder. Sealer A liquid that seals wood pores so they will not absorb subsequent coats. Sealers may be transparent, and can act as primers. Some sealers are designed to be left uncoated. Semi-transparent stain Stain that alters the natural colour of the wood, yet allows the grain and texture to show through. The term is generally applied to exterior products, but technically applies also to interior wiping stains used for trim, furniture and floors. Shellac Alcohol-soluble, clear to orange-coloured resin derived from lac, a substance secreted by insects. Previously used as a sealer and clear finish for floors, for sealing knots, and in “alcohol-borne” primers; rarely in use anymore. Thinner is denatured alcohol. It is an environmentally friendly product and usually available from finish suppliers. Solid-colour stain Exterior stain that obscures the natural colour and grain of wood, but still allows the texture to show through – essentially, a thin paint. Stain A coating product which can either be opaque such as a solid colour stain or partly transparent such as a semi-transparent stain. Also refers to wood discolourations such as discolourations caused by tannins in wood extractives, or stain caused by fungi such as bluestain. Solvent In generic coatings terminology, refers to the volatile liquid used to improve the working properties of a coating, typically water or hydrocarbons. In “solvent-borne” coatings, refers specifically to a coating based on hydrocarbons. Tung oil Obtained from the nut of the Asian tung tree. Hardly ever used in the raw state as it dries to a non-lustrous finish. Used in varnishes. Varnish Generic term for clear film-forming finish. Transparent or translucent liquids applied as a thin film, which harden. Can be solvent or water-borne. VOC Volatile organic compound. VOCs are organic chemical compounds that have high enough vapour pressures under normal conditions to significantly vaporize and enter the atmosphere where they may participate in photochemical reactions. They are often associated with solvents, typically considered to be pollutants, and are the subject of regulations in many jurisdictions.
Canadian Preservation Industry
Canada has had a wood preservation industry for about 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 65 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 and CA. The industry began its substantial shift to the water-borne products in the 1970s, as consumer interest in decks and other residential outdoor structures dramatically increased. For many years, CCA was by far the dominant preservative for both residential and industrial applications. In 2004, CCA regulations were changed such that CCA is no longer available for many residential applications. Subsequently, Canadian treaters have shifted about 80% of their previous CCA production to ACQ or CA. Most of Canada’s treated wood is used domestically; Canada exports only 10% of its production. Canada has its own wood preservation standards, supports several technical and marketing organizations, and maintains a lead position in certain areas of wood preservation research. A major focus of the industry has been in response to increasing levels of health and environmental protection regulations.
Durability Research and Development
FPInnovations has been field testing the performance of treated wood products for years. Click one of these categories for performance data from our field tests. Borate-treated Wood vs. Termites Naturally Durable Species The heartwood of species reported to have some natural durability was evaluated in ground contact (stakes) and above-ground (decking) tests. Commodity: 2×4 and 2×6 lumber from naturally durable species: Western redcedar, yellow cypress, eastern white cedar, larch, tamarack, Douglas-fir Control species: Ponderosa pine sapwood Test method: Stake test (AWPA E7) and Decking test (AWPA E25) Test sites: FPInnovations – Maple Ridge, BC; Petawawa, ON Michigan Technological University – Gainesville, Florida; Kipuka, Hawaii Date of installation: 2004-2005 Estimated service life: In the ground-contact stake test, after 5 years moderate to high levels of decay were found in all species at all sites. Yellow cypress and western redcedar were the most durable at all site. Eastern white cedar had similar durability at the Canadian and Florida sites, but was less durable in Hawaii. There were no major performance differences observed between old-growth and second-growth materials used in this study. Untreated naturally durable heartwood is not recommended for long-term performance in ground contact. In the above ground decking test, at the Canadian test sites after 10 years only small amounts of decay were observed in any of the naturally durable heartwoods tested. In contrast, the ponderosa pine controls had moderate to advanced decay. Decay was more rapid at the Florida and Hawaii test sites, with moderate to advanced decay present in all material types after 7 years. Untreated naturally durable heartwood is not recommended for long-term performance in exposed above ground applications in high decay hazard areas such as Florida and Hawaii. However, in temperate climates these naturally durable heartwoods can provide service lives greater than 10 years. References: Morris, P. I., Ingram, J., Larkin, G., & Laks, P. (2011). Field tests of naturally durable species. Forest Products Journal, 61(5), 344-351. Morris, P. I., Laks, P., Larkin, G., Ingram, J. K., & Stirling, R. (2016). Aboveground decay resistance of selected Canadian softwoods at four test sites after 10 years of exposure. Forest products journal, 66(5), 268-273.
