COST Action E49 Processes and Performance of Wood-Based Panels

WG3 SOA: Structural Integrity of WBP and their Connections

Prepared by:

Marija Aleksovska, Kiril Gramatikov, Bruno Dujic

Contents

1. CAPTION 1

2. ENGINEERED WOOD PRODUCTS 2

2.1 LINEAR PRODUCTS - STRUCTURAL COMPOSITE LUMBER - SCL 3 2.1.1. LAMINATED VENEER LUMBER-LVL 3 CROSS-BANDED LVL 4 2.1.2. LAMINATED STRAND LUMBER- LSL 4 2.1.3. PARALLEL STRAND LUMBER- PSL 6 2.2. PANEL PRODUCTS 7 2.2.1 FIBREBOARD 7 2.2.2 FLAKEBOARD 11 2.2.3. VENEER BOARD 12

3. APPLICATIONS OF EWP SYSTEMS 13

3.1 WALL SYSTEMS 14 3.2 FLOOR SYSTEM 14 3.3. ROOF SYSTEMS 15 3.4. FOUNDATION SYSTEMS 15 3.5. HYBRID SYSTEMS 16 3.6. FURNITURE COMPONENTS 17 3.7. I-JOISTS 17

4. APPLICATIONS OF THE PRODUCTS 18

5. JOINTS AND CONNECTORS 23

5.1. NAILS 25 5.2. SCREWS 25 5.3. BOLTS 26 5.4. LAG SCREWS 27 5.5. SPLIT RINGS AND SHEAR PLATES 28 5.6. FRAMING CONNECTORS 28 5.7. JOIST AND PURLIN HANGERS 30 5.8. ADHESIVES 31 5.8.1. ADHESIVES USED FOR LAMINATED PRODUCTS 31 5.8.2. INTERIOR WOOD PRODUCTS 32 5.8.3. EXTERIOR WOOD PRODUCTS 32 5.9. GENERAL GUIDELINES FOR CONNECTIONS 32

6. REFERENCES 33

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1. Caption Homes and other buildings are getting larger, and trending toward more open space. These two factors combined mean longer floor spans and greater loads on those spans. With the new engineered wood products these two factors are reality. A EWP (Engineered Wood Product) is a wood product that has a set of design properties assigned to it. EWP’s are also often defined as a combination of smaller pieces of wood that together create larger high strength structural elements or components. Engineered wood includes a wide range of products manufactured by bonding together wood strands, veneers, lumber, or other forms of wood fibre to produce a larger and integral composite unit. Structural engineered wood products are “engineered” by virtue of possessing design values that are confirmed by methods other than simple visual grading. APA divides structural engineered wood products into four general categories: 1) wood structural panels, including plywood, oriented strand board, and composite panels; 2) glued laminated timber (glulam); 3) structural composite lumber (SCL), including primarily laminated veneer lumber (LVL), but also parallel strand lumber and oriented strand lumber; and 4) wood I-joists. These products are extremely efficient because they utilize more of the available resource with minimal waste. In addition, in many cases, they are produced using faster growing and often underutilized wood species from managed forests and tree farms, thus reducing the industry’s reliance on “old-growth” forests. EWP’s are manufactured by mechanical connecting systems, adding adhesive, shaping, pressing, curing, finishing.

Engineered wood components include: plywood, oriented strand board, panels, glue laminated beams, solid sawn lumber, visually graded, machine stressed rated, machine evaluated lumber, metal plate connected wood trusses, composite structural lumber which would include laminated veneer lumber and parallel strand lumber, as well as I-joists.

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2. Engineered Wood Products Engineered wood components can be grouped into linear and panel products. Each of these products has passed through some manufacturing or other process to determine numerical engineering property values within a degree of certainty or reliability.

Medium Density Fiberboard (MDF)

• Sanded for uniform flat surfaces; • Uniform Density; • Core is ground much finer than PBC;• Edges look more like wood;

Particle Board Core (PBF)

• Ideal for cabinets/countertops; • Core bonded with synthetic

resins; • No telegraphing of substrate;

Lumber Core

• Consists of glued solid lumber strips; • Strips run parallel to the face for

strength; • Panel edge can be shaped to

resemble solid lumber;

Veneer Core (VC)

• Most common core; • Suited for cabinet & casework; • Cross-ply technique with 3, 5, 7,

9, or 13 plies;

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2.1 Linear products - Structural Composite Lumber - SCL Structural Composite Lumber differs from other products, in that is made from very small pieces of wood. Some of the raw material stock is too small, or of improper shape to be used in either a linear or panel EWP process, and is reallocated to SCL production saving waste, and the environment. Structural Composite Lumber- SCL

• Laminated Veneer Lumber LVL • Laminated Strand Lumber LSL • Parallel Strand Lumber PSL

2.1.1. Laminated Veneer Lumber-LVL

LVL is quite similar to the vertically laminated glulam beams, but is made in a similar manner to plywood. Ply material is peeled off good quality logs and vertically laminated with the grain on each ply running in the same direction. LVL is an engineered wood product that uses multiple layers of thin wood assembled with adhesives. Laminated veneer lumber is manufactured using parallel lamination into the veneers.

Phenol formaldehyde or isocyanurate adhesives are used to glue the sheets of veneer together. The defects that occur in each individual veneer sheet are randomized throughout the product during the assembly or “lay-up” process. This gives orthotropic properties in a similar way to the properties of sawn timber, rather than the nearly isotropic properties in the plane of plywood.

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The resulting composite has a high strength due to its decreased variability. It offers several advantages over typical milled lumber: it is stronger, straighter, and more uniform. It is much less likely than conventional lumber to warp, twist, bow, or shrink due to its composite nature. Made in a factory under controlled specifications, LVL products allow users to reduce the onsite labor. The end product that is available in the market place is available in sizes that are very similar to the sizes that are available in lumber. Work began on the development of this material back in the 1940’s as it was being used for high-strength aircraft structures. By the late 1960’s and early 1970’s, the process was developed for continuous laminated veneer lumber manufacturing. They are typically used for headers, beams, rim board, and edge-forming material.

Cross-banded LVL

Cross banded LVL is manufactured by including one or two laminations in the cross section with the grain running perpendicular to the longitudinal axis of the sheet. This product has advantages when used in specific applications:

• Short span deep beams produce very high shear stresses compared with the flexural stresses. The cross-banding removes some of the wood fibre that contributes to bending strength and stiffness and substitutes it with fibre that contributes to shear strength.

• Elements that are curve or taper cut from sheets have slope of grain that is at an angle to the flexural stresses. This would normally tend to cause splitting along the grain lines, but the cross-bands provide fibre with strength in the direction that will minimise those splits.

• Elements that are used in an environment that may have changeable moisture content may tend to split on wetting and drying. The cross-banding will reduce the tendency of these elements to split.

Cross-banded LVL has a different set of properties to LVL with all plies parallel to the longitudinal axis. The shear strength is higher and the tensile strength perpendicular to the grain is also considerably higher. The flexural strength is marginally lower and the MoE parallel to grain is also a little lower.

2.1.2. Laminated Strand Lumber- LSL

LSL is manufactured from strands of a single wood species or a combination of wood species blended with an isocyanate-based adhesive. Shorter strands than used in PSL are

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used to manufacture LSL. LSL is an engineered structural material that is manufactured by bonding wood veneers or strands together with a structural adhesive to form a solid member of end sections and length limited only by manufacturing, transport and handling capabilities. The grain direction of each veneer or strand is usually orientated parallel to the length of the piece but may be cross-banded for speciality applications.

Laminated strand lumber (LSL) transforms plentiful, fast growing aspen or yellow poplar trees into long, wide billets of high-grade engineered timber with greater strength than ordinary timber and fewer defects. The billets are precision-cut into standard section components suitable for use as part of the system in residential applications - including short and intermediate span beams, lintels and columns. LSL provides a strong, cost effective alternative to conventional timber or steel beams. Manufactured to a low, consistent moisture content LSL virtually eliminates the cupping, bowing, twisting and splitting so common with sawn timber. The workability and high strength-to-weight ratio of LSL make it a logical alternative to steel beams and lintels. Laminated strand lumber (LSL) is a structural composite lumber (SCL) first developed in the late 1960’s as an alternative to sawn lumber and other traditional structural wood products. Its manufacture permits a product with a high degree of consistency and an efficient use of low-grade fibre. Consequently, LSL is an environmentally positive and structurally valuable material, providing the structural engineering community with an alternative to traditional sawn lumber. Having only been available on the market for approximately 25 years, there is a limited amount of research-based information available on LSL, especially on connections. The connection rules are based on sawn and glued laminated lumber research. Tabulated design values are provided for a variety of wood species and some engineered wood products, with the exclusion of LSL.

Because of its laminated structure, dispersing strength reducing characteristics more evenly, LSL and LVL have higher bending strength and stiffness than the equivalent solid timber section of the same species. LVL and LSL are produced in the seasoned condition. LVL and LSL are usually manufactured as ‘billets’, 1.2 m wide for LVL and 2.4m wide for LSL, in a number of thicknesses (depending on the manufacturer) and in lengths up to 12 m or more from some manufacturers.

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Structural member sizes are re-sawn from the production billets in a range of standard widths, depending on the individual manufacturer. Curved shapes can be manufactured, provided the curved profile can be cut from the production “billets”. Commonly available stock widths and depths are as follows but advice should be sought from individual manufacturers prior to specification. LVL and LSL are generally not considered an appearance product, as glue lines are often quite visible. However, they may be coated with an opaque finish, after a light sanding if the unfinished appearance is not acceptable in visually exposed applications.

2.1.3. Parallel Strand Lumber- PSL

PSL is manufactured using parallel strands of wood fibre. PSL is made from 1/2” wide random length strips of veneer that are coated with resin, aligned, and fed into a press. The strips are compressed, and with the addition of microwave energy to cure the glue, formed into a large rectangular-section billet. Because the process is continuous, any length billet can be produced. After cooling, the billet can be sawn into any cross-section desirable, although standard sizes are produced. Manufacturing process allows production of large solid cross-sections, as opposed to individual thinner pieces which have to be attached together.

Small specimens were prepared from commercial southern pine PSL and yellow-poplar PSL billets and tested for specific gravity, moisture content, dimensional stability, bending properties, shear strength and compressive strength. Results indicate average specific gravity of southern pine PSL is higher than that of yellow-poplar PSL, while their average moisture content and dimensional stability are very similar. Southern pine PSL has higher average modulus of elasticity but lower average modulus of rupture than yellow-poplar PSL. While average longitudinal shear strength does not exhibit differences between southern pine PSL and yellow-poplar PSL, average compressive strength of southern pine PSL is higher than that of yellow-poplar PSL. There are positive correlations among modulus of elasticity, modulus of rupture and specific gravity. PSL improves some properties of solid wood from which PSL is made. It is available to the

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marketplace in beam and lumber like sizes. It uses strands of veneers that are all oriented in the same direction. Developed in the late 1960’s and early 1970’s by MacMillan Bloedel. It became commercially available in the early 1980’s.

The beauty of PSL isn’t just how it looks, but how and why it performs better than any other material for short-span bridges. PSL lumber makes far better use of available timber resources. High-tech manufacturing processes do not require harvesting of large-diameter trees from old growth forests as does sawmilling of timbers for ordinary timber bridge construction. As a wood-based product, PSL comes from a renewable and abundant resource trees. Wood building materials consume far less energy to harvest, manufacture and deliver than comparable steel and concrete products, which are derived almost exclusively from finite natural resources. And consider this PSL is made primarily from small-diameter, second-growth trees and doesn’t rely on the limited supply of high-quality sawn lumber.

2.2. Panel products A variety of EWP panel products are produced and are structural at different scales. For structural use in buildings, plywoods and OSB are the accepted standards. The remaining products serve a variety of uses from furniture, to siding, to trim and moldings, to underlayments. Panel products:

Fibreboards: o Particleboard; o Medium density fibreboard-MDF; o High density fibreboard- HDF; Flake boards: o Wafer board; o Oriented strand board (OSB); Veneer boards: o Plywood;

2.2.1 Fibreboard

Fibreboard is a type of engineered wood product that is made out of wood fibres. Types of fibreboard in order of increasing density include particle board, medium-density fibreboard and hardboard, also called high-density fiberboard.

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Fiberboard is sometimes used as a synonym for particle board, but particle board usually refers to low-density fibreboard. Plywood is not a type of fibreboard, as it is made of thin sheets of wood, not wood fibres or particles. Fibreboard, particularly medium-density fibreboard, is heavily used in the furniture industry. For pieces that will be visible, a veneer of wood is often glued onto fibreboard to give it the appearance of conventional wood.

The categories of fibreboard are as follows: 1. "Hardboard" is manufactured in the ‘wet production process’ in which the wood-fibres in suspension in water are compressed in the form of a mattress under high temperature and high pressure on a metallic mesh. In the unworked state this type of fibreboard has one smooth and one rough surface with a mesh pattern. However, it can sometimes also have two smooth surfaces obtained by special surface treatment or a special production process. It generally has a density exceeding 0.8 g/cm³. Hardboard is mainly used for furniture, in the automotive industries, for door skins and for packaging, especially fruit and vegetable packaging. 2. "Medium board" is also manufactured in the ‘wet production process’ in a way similar to the one for hardboard but at a lower pressure. It generally has a density exceeding 0.35 but not exceeding 0.8 g/cm³. The main application is in furniture production and for interior or exterior walls. 3. "Soft board" is also manufactured in the ‘wet production process’. However, this fibreboard is not compressed as the other types of fibreboard. It generally has a density of 0.35 g/cm³ or less. These boards are used mainly for thermal or sound insulation in building. Special types of insulating board are used as sheathing or sarking materials. 4. "Medium density fibreboard (MDF)" is manufactured in the ‘dry production process’, in which additional thermal–hardening synthetic resins have to be added to the dried wood fibres in order to assist the bonding process in the press. The density generally ranges from 0.45 to 1 g/cm³. In the unworked state it has two smooth surfaces. It can be used in lots of different applications such as furniture, interior decoration and in building. Medium density fibreboard (MDF) of a density exceeding 0.8 g/cm³ is sometimes also referred to by trade as "high density fibreboard (HDF)".”

2.2.1.1. Hardboard Hardboard, also called high-density fibreboard, is a type of fibreboard, which is an engineered wood product. It is similar to particle board and medium-density fibreboard, but is much harder and denser because it is made out of exploded wood fibres that have been highly compressed. It is sometimes referred to as masonite because that was the first brand. Unlike solid wood, it is very homogeneous with no grain. However, a wood veneer can be glued onto it to give the appearance of solid wood. Other overlays include Formica and vinyl. It has many uses, such as a substrate, but unlike plywood and solid wood, it has no structural strength to speak of. It is used in construction, furniture, appliances, automobiles and cabinetry.

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Hardboard is produced in either a wet or dry process. The wet process only leaves one smooth side, but dry processed hardboard is smooth on both sides. Like other types of fibreboard, hardboard is susceptible to moisture damage and is generally not used outside. Tempered hardboard is made by adding an oil that becomes a polymer when the board is formed under high temperature and pressure. This gives it more water resistance, hardness, rigidity and tensile strength. It is used in construction siding. Hardboard was invented by Daniel Manson Sutherland in 1898, at Sunbury Common in Spelthorne near London. He formed the Patent Impermeable Millboard Company to market and develop his invention.

2.2.1.2. Medium-density fibreboard-MDF Medium-density fibreboard - MDF is an engineered wood product formed by breaking down softwood into wood fibres, combining it with wax and resin, and forming panels by applying high temperature and pressure. It is a building material similar in application to plywood but made up of sawdust. It is denser than normal particleboard. Large-scale production of MDF began in the 1980s. Its name derives from the distinction in densities of fibreboard. MDF typically has a density of 600-800 kg/m³. Particle board is a low-density fibreboard and has a density of 160-450 kg/m³, while hardboard, also called high-density fibreboard, has a density of 500-1,450 kg/m³. Similar manufacturing processes are used in making all types of fibreboard. New MDF products include generic and proprietary panels. One example is a super-refined board in which fine fibres are distributed throughout the board to facilitate deep routing and machining. In some countries, panels are being made from many different hardwood and soft-wood species as well as from non wood based lignocelluloses from raw materials such as bagasse and cotton stalks. In South America and Australia, hardboard panels have been successfully produced from a variety of wood species including Eucalyptus grandis and E. saligna. In the United States, some panels are being produced from recycled fibers from postconsumer wood waste.

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2.2.1.3. Particle board Particle board, also called chipboard, is an engineered wood product manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extruded. Particle board is a type of fibreboard, a composite material, but it is made up of larger pieces of wood than medium-density fibreboard and hardboard.

Particle board is cheaper, denser and more uniform than conventional wood and plywood and is substituted for them when appearance and strength are less important than cost. However, particle board can be made more attractive by painting or the use of wood veneers that are glued onto surfaces that will be visible. Though it is denser than conventional wood, it is the lightest and weakest type of fibreboard, except for insulation board. Medium-density fibreboard and hardboard are stronger and denser than particle board. A major disadvantage of particle board is that it is very prone to expansion and discoloration due to moisture, particularly when it is no covered with paint or another sealer. Therefore, it is rarely used outdoors or places that have high levels of moisture, with the exception of some bathrooms, kitchens and laundries, where it is commonly used as an underlayment beneath a continuous sheet of vinyl floor covering. In such an installation the edges must be properly coved upward against the wall and joins and non-coved edges must be properly sealed against moisture penetration. A higher quality material not subject to expansion is underlayment-grade plywood, which is constructed without interior voids in its layers to better resist the high local pressure from objects such as stiletto heels. For many years, people have desired cheaper alternatives to solid, natural wood. Plywood was invented during the Second World War and was quickly taken up by the community. But by the end of the 1940s there was not enough lumber around to manufacture plywood affordably. Particle board was intended to be a more efficient replacement. While research had been done on particle board earlier, the first commercial piece was produced during the war at a factory in Bremen, Germany. It utilised waste material such as planer shavings, off cuts or sawdust, hammer-milled into chips and bound together with a phenolic resin. Hammer-milling involves smashing material into smaller and smaller pieces until they pass out through a screen. Most other early particle board manufacturers used similar processes, though often with slightly different resins. However, it was soon found that better strength, appearance and resin economy could be achieved by using more uniform, manufactured chips. Manufacturers began processing solid birch, beech, alder, pine and spruce into consistent chips and flakes. These finer

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layers were then placed on the outsides of the board, with the central section composed of coarser, cheaper chips. This type of board is known as three layer particle board. More recently, graded density particle board has also evolved. It contains particles that gradually become smaller as they get closer to the surface.

2.2.2 Flakeboard

2.2.2.1. Oriented strand board-OSB OSB is an engineered wood-based sheet material in which rather long strands of wood are bonded together with a synthetic resin adhesive. Sometimes in all three layers, but usually in only the outer layers of these three-layer panels, the strands are orientated in a particular direction. However, there is quite a large degree of variability in this orientation among adjacent strands in the panels from any one production line as well as between panels from different producers. Compared with many other types of panel products, OSB is a relative newcomer, first developed about twenty-five years ago.It is manufactured in wide mats from cross-oriented layers of thin, rectangular wooden strips compressed and bonded together with wax and resin adhesives (95% wood, 5% wax and resin). The layers are created by shredding the wood into the strips, these are sifted and then oriented on a belt. The mat is made in a forming bed, the layers are built up with the external layers aligned in the panel direction and internal layers randomly positioned. The number of layers placed is set by the required thickness of the finished panel, typically around a 15 cm layer will produce a 15 mm panel thickness. The mat is then placed in a thermal press. Individual panels are then cut from the mats in standard sizes. Different qualities in terms of thickness, panel size, strength, and rigidity, can be given to the OSB by changes in the manufacturing process. OSB panels have no internal gaps or voids, and are water-resistant (though they do require additional membranes to achieve impermeability to water). The finished product has similar properties to plywood, but is uniform and cheaper. It has begun to replace plywood in many environments. The most common uses are as sheathing in walls, floors, and roofs. While OSB does not have grain like a natural wood, it does have a specific axis of strength. This can be seen by looking at the alignment of the surface wood chips. The most accurate method, though, for determining the axis of strength is to examine the ink stamps on the wood placed there by the manufacturer. This is a new type of wood panel that will eventually completely replace plywood in residential and commercial construction. It is as good as the equivalent plywood which would have been used in that condition. OSB and similar new wood products were developed in response to changing resource availabilities and the desire by manufacturers to improve the efficiency of their operations. This adaptation also

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demanded a change in manufacturer's approaches to the design of their product, from one that focused on process to one that focused on results.

2.2.3. Veneer board

2.2.3.1 Plywood Plywood was the first type of engineered wood to be invented. It is made from thin sheets of wood veneer, which are stacked together with the direction of each ply's grain differing from its neighbours' by 90° (cross-banding). The plies are bonded under heat and pressure with strong adhesives, usually phenol formaldehyde resin, making plywood a type of composite material. A common reason for using plywood instead of plain wood is its resistance to cracking, shrinkage, twisting/warping, and its general high degree of strength. A vast number of varieties of plywood exist, all manner of conditions and uses. Softwood plywood is usually made either of Douglas fir or spruce, pine, and fir, and is typically used for construction and industrial purposes. Decorative plywood is usually faced with hardwood, including red oak, birch, maple, lauan (Philippine mahogany) and a large number of other hardwoods.

Plywood meant for indoor use generally uses the less expensive urea-formaldehyde glue (which has limited water resistance), while outdoor and marine grade plywood are designed to withstand rot and use a water-resistant phenol-formaldehyde glue to prevent delamination and to retain strength in high humidity. The most common varieties of softwood plywood come in three, five or seven plies with dimensions of 1.2 m × 2.4 m. Roofing can use the thinner 3/8-inch plywood. Floorboards are at least 5/8-inch depending on the distance between floor joists. Plywood is often tongue and grooved for flooring applications. Two of the edges will have "grooves" notched into them to fit with the adjacent "tongue" that protrudes from the next board. High-strength plywood, known as aircraft plywood, is made from mahogany and/or birch. It was used for several WWII fighter aircraft, including the British-built Mosquito bomber. Airplane plywood was adapted for furniture by Alvar Aalto. There is always an odd number of veneers and each ply is at a right angle to the one below, this gives the material it's strength. The more veneers used, the stronger the plywood becomes. Both the type of glue and veneers determine the suitability of a sheet for a particular application. The finish quality of plywood varies considerably, some plywood have attractive grains while others can contain knots.

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3. Applications of EWP systems EWP Systems have been traditionally used as framing material in the furniture and cabinet industries. Recent development of structural panel (i.e., oriented strandboard – OSB) and engineered lumber, including laminated veneer lumber (LVL), parallel strand lumber (PSL) and laminated strand lumber (LSL), provide an efficient and economic alternative. These products are manufactured with no core voids, knotholes and delamination problems. They can be easily sawn, drilled, nailed, planed, filed, sanded or painted to meet design specification. As a result, the products have been designed for numerous industrial applications including RV/campers, truck bodies, pallets, furniture fames, displays, shelving, construction barriers, racks, packaging, crating, void forms, bins and trunks and overlaid core. Acceptance of new products by the manufacturers and their customers has always been a slow process.

A better understanding of reasons for acceptance or rejection of structural panels and engineered lumber as raw material for furniture and cabinet framing could lead to further expansion of their uses by manufacturers and better sales and marketing by the raw materials manufacturers and distributors. Panel products such as particleboard and medium density fiberboard are important raw material inputs for the furniture, cabinet and allied industries. However, there are other wood-based products that are currently used or have the potential to be used in these applications. EWP Systems are used for:

walls floors roofs foundations built-up hybrid components furniture

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3.1 Wall Systems Walls are made up of a combination of panel and linear EWP’s connected in a specific way with fasteners. One of the functions of a wall is to provide in plane racking / shear resistance. Fastener number, size, and pattern are prescribed by code tables in order to properly connect the panel and linear EWP’s together to develop a measurable resistance. Walls don’t have to be plane in 2 directions. One-dimensionally planar walls allow for curving forms that still have a measurable rigidity.

3.2 Floor System The I-joists are responsible for resisting bending and deflection which is influenced by their depth. The addition of the sub floor panel EWP adds a measure of T-beam action to help stiffen the system further. I-joists typically use L/480 deflection criteria because of long-span capabilities. The wide flanges of the I-joists allow workers to more easily work on top of the I-joists. However, the I-joists must be secure from tipping over before workers are allowed to walk on them. This often means the installation of rim boards to hold the ends in position, or additional x bracing or blocking installed to provide intermediate lateral support. When framing into other members, preformed sheet metal hangers specifically made for I-joists are used. Be sure to get the required load capacity out of the hanger by installing all required fasteners of the required size.

Accompanying the most recent tendencies, new flooring ranges and solutions are being launched making laminate flooring look more and more like real wood:

• Large panels in different patterns representing the newest design tendencies; • the newest solution for commercial areas; • different sound reduction systems with integrated 2mm underlay; • surface finishing similar to traditional wood floors so that nature can go indoors;

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These kind of flooring substrates gives a multitude of choices to create in each room, piece by piece, exclusive tailor made spaces. A wide range of patterns ready to seduce, and a complete accessories range allowing having the perfect finishing desired.

3.3. Roof systems Rafters, purlins, ridge boards, and hip or valley members can be sawn lumber, end jointed lumber, or any one of a variety of prefabricated (engineered) members. Examples of engineered lumber include wood I-joists or solid rectangular structural composite members such as parallel strand lumber (PSL), laminated veneer lumber (LVL), or laminated strand lumber (LSL). Roof beams and blocking can be either sawn lumber or engineered lumber. I-joists are excellent for rafter components, especially where energy efficient designs require depth in the member for insulation and venting requirements. Framing into a ridge beam is easily made with preformed sheet metal hangers. Plywood blocks prevent rotation of the I-joist in the hangers.

3.4. Foundation Systems Preserved Wood Foundations is also a system of EWP’s specifically manufactured for this use. Because of the forces involved, the solution must be engineered. Many homes are being built with a Preserved Wood Foundation (PWF). A PWF is an engineered load-bearing wood-frame system designed as a foundation for light-frame construction (single family homes, room additions etc.). PWFs offer many advantages over other types of foundations, for both the builder and the home owner. With insulation installed in the stud wall cavities, the PWF can save energy and heating costs. PWFs are dry, comfortable, easy to finish, and more economical to convert to fully liveable space than a masonry foundation. All lumber and plywood used in a PWF, except in limited locations, must be treated with preservative. A PWF can be easily constructed in all but the most inclement weather, using standard sizes of studs and plywood, and can even be factory-prefabricated for added quality control.

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3.5. Hybrid Systems Entire building systems can be formed from a collection of EWP’s acting as together forming hybrid components. On large-scale projects, hybrid systems can represent a significant savings in time and cost of erection, while producing a high quality end product. System-oriented products for timber construction are an intelligent way of using wood-based panels: I-joists, OSB, fibreboard insulation panels, roof and wall panelling for vapour diffusion MDF or particleboard. Wood-based construction is an obvious option. It is natural, beautiful and eco-efficient.

And building and construction systems are cost-effective thermal and sound insulation solutions that meet all relevant structural, fire protection, soundproofing and environmental requirements. Maximum benefits can thus be expected from sophisticated building systems. The new engineered wood products are used for bridge designs. One group of engineered wood products that has been adapted for bridge applications is structural composite lumber (SCL),

which includes laminated veneer lumber (LVL) and parallel strand lumber (PSL). LVL is made from thin sheets of rotary-peeled wood veneer that are glued together with waterproof adhesive. PSL consists of narrow strips of veneer that are compressed and glued together with the wood grain direction parallel. There are several characteristics which make SCL wellsuited for bridge applications. Because it is a manufactured product, SCL can be produced in a variety of sizes and shapes. The laminating process disperses the natural strength-reducing characteristics of wood, which reduces product variability and provides significantly improved design strength and stiffness compared to sawn lumber. SCL also provides excellent treatability with wood preservatives, and full preservative penetration is typically achieved.

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3.6. Furniture Components The manufacture of Particle Board began on a large scale after World War II as a low cost replacement for lumber and plywood in furniture and cabinetry. Some twenty years later, in 1966, the first MDF plant began production. Used primarily as core material for doors, furniture, and cabinets, particleboard often is covered on one or both sides with veneer or another surface finish. In housing construction, particleboard is used under carpet or other finished surfaces as floor under laymen and stair treads. It is also used as floor decking in mobile homes. MDF is used as a replacement for wood boards in furniture, cabinets, moldings, and picture frames. Demand for Particle Board and MDF has grown dramatically in the past decade, replacing more and more solid wood lumber and plywood products. Also, hardwood and plywood panels are used in store fixture manufacturing, cabinets, furniture and some architectural designs. With quality and competitiveness being the key issues, the range includes all the main types of prefabricated furniture components, from simply cut and edge banded panels to soft formed and drilled parts, with grooves or dowels. The versatility of these installations makes it easy to supply different profiles, slightly shaped, standard or customised.

3.7. I-joists I-joists began the marriage of linear and panel wood products in a hybrid structural component. The I-shape has been long known for its efficiency in bending strength and deflection control. This has led to a new level of structural, material, and environmental efficiency. The concepts for wood I-joists were developed in the late 1950’s. In the mid-1960’s Trus Joist Corporation developed the machinery to mass-produce I-joists. What this machine basically did was put a route in the lumber or LVL flanges into which the plywood was forced and adhesive was applied and then cured to provide a very tight and efficient joint. Market has grown significantly in the late 1970’s and early 1980’s.

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Because for the proprietary nature of the I-joist product, a number of styles have been produced, with different materials in the flanges and webs, as well as different connection between the web and the flange. I-joists can be deep or shallow, usually in sizes that match common dimension lumber depths, or other EWP’s such as glulam sizes.

4. Applications of the products LVL and LSL products are used predominantly for residential and industrial structural building applications such as floor joists, lintels, purlins, roof truss components, etc. The ability to cut different shapes from productions “billets” allows for structural innovation using angular and curved shapes. While it’s unfinished, manufactured appearance may limit its use for high quality appearance applications, the use of opaque finishes will facilitate the use of LVL or LSL in creating visually exciting structural forms.

LVL Floor System

An LVL floor system is a three-part system designed to replace traditional dimensional lumber joist systems. Through the use of advanced engineering, lumber is chipped, structurally aligned and bonded in thin sheets at extremely high pressure. The sheets are then laminated together (once again at extremely high pressure) to form consistently stable boards much stronger than typical dimensional lumber. The system components include:

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LVL beams are designed to replace the standard dimensional beams in a traditional floor system. The high pressure, aggressive adhesive and grain orientation of the chips makes the layers significantly stronger than standard lumber of the same size. Their construction also makes LVL beams straighter, more dimensionally consistent and less susceptible to warping or compression.

I-joists are designed to replace the dimensional joists used in a traditional floor system. I-joists resemble traditional steel I-beams with two flanges and a web. The flanges are laminated and layered in the same manner as LVL beams. The flanges provide most of the load carrying capacity in the I-joist. The web is laminated similar to oriented strand board (OSB), but under much greater pressure and with stronger, more aggressive adhesive. The web serves to hold the flanges together and absorbs vibration in the floor. I-joists can span up to 25 percent greater distances than comparably sized dimensional lumber boards.

Rim boards are designed to replace the rim joists used in traditional floor systems. Rim boards are used around the outside of the floor system to stiffen the I-joists. They also serve to transfer the load to bearing walls or foundations.

When all three parts are used together, they yield a much stronger, more stable floor system. The stronger floor system results in a more solid feeling in the entire floor with less chance for squeaks. PSL products are used for headers, primary carrying members, columns, beams. PSL products are used for residential, industrial structural building systems and maybe the most important for bridges.

For example, Parallam® PSL bridges offer solutions for today’s short-span bridge projects. Advances in engineered timber materials, bridge design and component fabrication allow for bridge projects that cost less, save time, require minimal maintenance and provide long-lasting quality and beauty. Compare PSL to concrete, steel and other wood-based bridge materials. The unique features of this material lead most industry experts to assume an effective lifespan of more than 60 years for properly treated

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PSL. This lifespan is equal to steel and concrete bridges and substantially longer than conventional timber bridges. PSL bridges provide an aesthetic quality that blends in with natural, rural surroundings. PSL also resists warp, thermal expansion, shock and de-icing salts—factors that can affect the integrity and long-term durability of other bridge superstructures.

Installing Parallam® PSL bridges takes only a few days, using smaller and less-expensive erection equipment. These lightweight, prefabricated wood components can be installed year-round; no curing means no delays or temperature constraints. The Trus Joist bridge system can be installed directly on the existing abutments if they are in usable condition. HDF panels are highly recommended for use in the manufacture of heavy duty flooring. Its application can be extended to institutional furniture, doors for kitchen and bedroom units, staircases, industrial shelving, moldings, exhibition stands and displays, classroom and play area furniture, laboratory and workshop fittings, hotel restaurant and bar furniture, office furniture, components for the transportation industry requiring rigid and harsh conditions in actual service life. High density means superior screw and fastener holding and better installation of every type of cabinet hardware. The machined core surface is ideal for finishes, paints, foils, lacquers, etc., saving materials, time and labor. The superior stability and strength lends itself to manufacturing special shapes where impact, load and durability are concerns. The range of size and thickness, ease of availability and versatility of the product itself are a specifier’s dream. It is generally conjectured that wood-based fibreboards show a greater resistance to decay and termite damage than solid wood.

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MDF panels - In recent years, great changes have taken place in the MDF industry. Nowadays, we cannot talk about wood-based panels without thinking of MDF. Probably the most successful substitute for solid wood, the consumption of MDF continues to rise all over the world. From furniture grade to flooring and HDF types, from moisture resistant boards to fire retardant grade, from low density to thin boards or moulding grade. The popularity of this relatively new panel product is due to its ability to be produced in molded form, as well as in straight-edged flat panels, for a host of industrial markets. MDF is used extensively in factory-assembled and ready-to-assemble furniture, as well as in cabinets, underlayment, drawer fronts, molding, and countertops. Finishes and overlays can be used to provide a grain pattern typical of lumber, and many wood finishing components such as door edgings, decorative trim, frames, and cornices are being made from MDF. Moreover, MDF is replacing thin ply-wood and wet-process hardboard in the production of molded and flush door-skins.

Particleboard-As the most common type of wood-based panel in the world, particleboard is a very versatile product in terms of its possible uses and applications. Suitable for all general uses in furniture and construction, in dry or occasionally wet conditions or for fire retardant applications, the standard particleboard offers a uniform, smooth and clean surface on a conventional three-layer panel. It can be used raw or surfaced with wood veneers, melamine decorative papers or even thin foils.

Available in a very wide range of sizes and thicknesses, particleboard also offers solutions for flooring (access flooring and tongue & grooved), doors (homogeneous and compact) and free-formaldehyde applications. Particleboard has had an enormous influence on furniture design. In the early fifties, particleboard kitchens started to come into widespread use in furniture construction. However, in many cases it remained more expensive than solid wood. A particleboard kitchen was only available to the very wealthy. This did not last long though. Once the technology was slightly more developed, particleboard became much cheaper.

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Its low price has enabled more furniture to become available to many more people. Large companies such base their strategies around providing well-designed furniture, at a low price. In almost all cases, this means particleboard. Ikea’s stated mission is to “create well designed home furniture at prices so low as many people as possible will be able to afford them”. They do this by using the cheapest materials possible, as do most other major furniture providers. As a result, solid wood furniture has become an expensive luxury and particleboard the norm.

Particleboard’s main selling point is its price. However, it has several other significant advantages. One of these is its stability. Solid wood is prone to warping and splitting with changes in humidity, whereas particleboard is not. This stability enables new design possibilities, without having to take into account the seasonal variation. When exposed to high levels of moisture however, untreated particleboard will disintegrate. OSB - This engineered wood-based panel is suitable for structural and non-structural use in the construction industry. The three bonded layers of resinous wood strands arranged at right angles to one another, give a strong and stable panel free of defects and with high moisture resistance. The formats of OSB assure a great versatility in wall construction. The conditioned panels provide exceptional stability and strength and are economical and easy to use. Resistance to moisture means that OSB is suitable for warm and cold roofs. The product can take practically all kinds of coverings including bitumen, tiles and slates. Combined with solid wood to form I-joists, it makes large-scale construction easy and economical. OSB is also ideal for use in flooring, from dry domestic use to heavy-duty industrial use in humid conditions, with tongue and groove on 2 or 4 edges for supported and floating floors. As it has a natural wood-like look and can easily be stained and varnished, OSB offers many decorative options. Strength combined with lightness as well as the availability of large sizes allow for many options in industrial packaging. OSB can be a cost-effective alternative to other panel products for a wide variety of packaging options for use in dry and humid conditions. Last but not least, OSB is in fact an eco-efficient option as it presents very good mechanical performances using as raw material only small diameter round wood from fast growing species.

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Plywood is the traditional panel of choice for flooring, sheathing, home remodeling and industrial applications, such as frames for upholstered furniture. Plywood is used in any application that needs high quality wooden sheet material. High quality in this context means resistance to cracking, breaking, shrinkage, twisting and warping. Plywood is also used as an engineering material for stressed skin applications. In boating and in aviation, there's a history of using plywood this way going back to the WW-II era. Most notably is the British De Havilland Mosquito bomber which was primarily made out of wood. Even nowadays, plywood is used in stressed skin applications quite successfully. Plywood may be used inside and outside. Plywood is graded for exterior or interior use depending upon the water resistance of the glue used to stick the plies together. Sheds and cladding are made from this material. Weather boiled proof plywood requires paint or varnish to protect the outer veneer from the elements.

Internal plywood does not contain water-resistant adhesive. It may be used for wall panelling, flooring and furniture. Shuttering boxes are made from shuttering plywood. Shuttering boxes are used in the construction industry to contain concrete while it sets. The material is water resistant to a certain extent. The surface of this material does not have a decorative veneer and is generally not suitable for use where an attractive quality finish is required. Marine Plywood is made with waterproof adhesive so that it can be used under water. The material should still be protected with paint or varnish. The smoothness of the surface and the number of defects in it grade plywood. Plywood can be nailed and screwed. Thin plywood is flexible and can be formed into curved shapes.

5. Joints and Connectors Joining EWP’s is the same as joining solid timber. Traditional fasteners such as nails, screws and bolts can be used as well as proprietary metal connectors such as framing anchors, joist hangers etc. Concealed or exposed plates can also be used to secure butt connections such as in portal knee joints and joins in curved members. At supports it is essential that minimum bearing requirements be achieved. This may vary between different manufacturers.

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As for all other building materials, a critical aspect of wood structures is the manner by which members are connected. Wood products are building materials which are easily drilled, chiselled, or otherwise shaped to facilitate the connection of members, and a number of methods and a wide range of products are available for connecting wood. The installation of metal fasteners is the most common method of connecting wood products and a wide range of hardware is available. These range from the nails and the light connectors used for light framing construction to the bolts, side

plates and other hardware used for heavy member connections. Each type of fastener is designed to be used with a particular type of construction. When used appropriately, metal fasteners provide means of connection which are easy to install and which offer trouble free performance. Nailing for example, which is a basic means of connection with which everyone has some degree of familiarity, is an effective means of connection which, when applied according to specified layouts, results in strong structural systems which perform well under the most adverse loading conditions such as the effects of earthquake. The performance of metal fastener connections is based upon the fasteners being large enough to carry and transfer loads over a large enough area of the wood so that the wood fibre in contact with the fastener is not deformed.

Timber joinery is a traditional method of connecting wood members without the use of metal fasteners. Although the use of metal fasteners for connections is almost universal, timber joinery still offers a unique visual appearance exhibiting a high degree of craftsmanship. The cellular structures of wood and modern chemistry combine to produce glue bonds between wood members which are as least as strong as the wood fibre itself. For this reason, adhesives play a crucial role in the manufacture of wood products such as plywood and parallel strand lumber (PSL). They are also used structurally, for example, in improving the performance of floor assemblies.

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For many applications, such as nailing for frame wall construction, metal fasteners serve only a structural purpose, and will be hidden from view by interior and exterior finishes. In other cases where wood members serve a structural purpose and are left exposed to add visual interest to a design, as much thought must be given to the appearance of connections as to the selection and finishing of the wood products themselves. Where metal fasteners are exposed to view, the designer will in some cases will want them to be as inconspicuous as possible. This can be done by selecting fasteners such as split rings and bolts (which are effective means of transferring loads), by reducing the visual impact of hardware such as steel side plates by recessing them into the wood members, or by using painting to reduce prominence. In other cases, it may be desired to highlight the hardware to give a robust appearance to a structure.

5.1. Nails

Nailing is the most basic and most commonly used means of attaching members in wood frame construction. Usually, nailing is used as a structural connection and appearance is not a factor. Exceptions to this are nails used for cladding, decking and finish work, where care in the selection of the type of nail can lead to enhanced appearance. Screws rely on their threads to develop resistance to withdrawal. Nails are faster to install but rely mainly on friction to resist withdrawal. For this reason, designs should ensure that nails are loaded laterally and that withdrawal loads are

kept to a minimum. Nails are manufactured in many types and shapes to suit specific applications.

Common (spike) Eavestrough (spike) Standard or Common Box

Finishing Flooring and Casing Concrete Cladding and Decking

Clinch Hardwood Flooring Roofing Wood Shingle

5.2. Screws Wood screws are usually used for millwork and finishing rather than for structural framing. They are used in fastening millwork where resistance to withdrawl is a requirement. Screws find some applications in structural framing as in the case of floor sheathing which is glued and screwed to the joists or the positive attachment of gypsum

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wallboard to support members. They are higher in cost than nails because of the machining required to make the thread and the head. Screws are designed to be much better at resisting withdrawl than nails. However, when used for structural purposes, it is better that screws not be loaded in withdrawl but rather use the withdrawl resistance properly to produce and maintain close contact between the elements being joined. The types of wood screws commonly used are shown below.

Double Lead Single Lead Tapping

5.3. Bolts Bolts are used with plates, washers, or more efficiently, in conjunction with split rings or shear plates to connect wood members. They are often used in purlin to beam, beam to column, or column to base connections of wood structures. When bolts are used alone with washers or side plates the load transfer area of the wood is the surface area of the bolt. Timber connectors such as split rings and shear plates are a means of distributing loads over a larger area of wood and are discussed later in this section. Several types of bolts are used for wood construction with the hexagon head type being the most common. Countersunk heads are used where a flush surface is desired. Carriage bolts can be tightened by turning the nut without holding the bolt since the shoulders under the head grip the wood.

Types of Bolts for Wood Construction

Finished Hexagon Bolt

Square Headed Machine Bolt

Machine Bolt with Countersunk Head

Carriage Bolt

Bolts are installed in holes drilled slightly (1.0 to 2.0mm (1/32" to 1/16") larger than the bolt diameter to prevent any splitting and stress development that could be caused by

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installation or subsequent wood shrinkage. Wood shrinkage requires special consideration in the design of bolted connections for sawn timber because of the potential high moisture content of the members. It is less important in designing connections for glulam, PSL, or other wooden products manufactured at low moisture control. As shrinkage across the grain takes place in timber, movement may be restrained by the steel side plates leading to splitting of the wood. If steel side plates hold bolts further than 125mm (5") apart across the width in a splice joint, separate side plates.

Joint Spliced with Wood Side Members

Joint Spliced with Steel Side Plates

Joint Spliced with Multiple Steel Side Plates

5.4. Lag Screws Lag screws are bolts with sharp points and coarse threads designed to penetrate and grip wood fibre. They are used to anchor metal, or wood, to wood in areas inaccessible to the placement of a nut for a through bolt, or where an especially long bolt would be needed to penetrate a joint fully. Although lag screws do have some unique applications, through bolts are considered to be a more positive means of connection since they are less dependent on workmanship for reliable installation. The resistance of a lag screw generally increases with the length of the embedded thread portion. However, it is also affected by other considerations such as side plate thickness. As with other types of metal fasteners, sufficient end and edge distance must be provided to prevent splitting and to provide sufficient area for shear and bearing resistance in accordance with engineering design codes.

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5.5. Split Rings and Shear Plates Split rings and shear plates are load transferring devices which rely on bolts or lag screws to restrain the joint assembly. They are more efficient structurally than bolts or lag screws used alone because they enlarge the wood area over which a load is distributed. Split rings and shear plates are used mainly to transfer loads in heavy timber or glulam members as in roof trusses. These connector units transfer shear either between the faces of two timber members or between a timber member and a metal side plate. They are not usually protectively coated and need be galvanized only if used with preservation treated wood or in wet service conditions. It is important that the proper size of bolt be used with a connector since it is an integral part of the assembly. The bolt clamps the joint together so that the connector acts effectively.

Bolted Joint

Split Ring Connector Joint

Shear Plate Connector Joint

5.6. Framing connectors Framing connectors are made of sheet metal and are manufactured with prepunched holes to accept nails. They are used to provide a more positive connection between wood members by allowing the nails securing the framing connector to be loaded laterally rather than in partial withdrawl as would be the case if the members were toenailed together.

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They are also used in frame construction where additional protection is required against uplift from seismic or wind induced forces. Framing connectors are suitable for most joints in wood framing of 38mm (2" nom.) and thicker lumber. These include connections between joists and headers; rafters and plates or ridges; purlins and trusses; and studs and sill plates. The load transfer capacity of framing connectors is affected by the thickness of steel used. Standard duty framing connectors are commonly made of 18-gauge zinc coated sheet steel. Medium and heavy-duty anchors are made from heavier zinc-coated steel usually 12 gauges and 7 gauges respectively. They are suitable for similar connections between larger members where the loads to be carried exceed those permissible for the light anchors such as: header or beam to post; purlin to beam; and purlin to truss.

All-purpose framing anchor

Tie-down framing anchor

Framing angle

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Joist and purlin hangers

Truss plates

Triple grip framing anchor

5.7. Joist and Purlin Hangers Framing connectors are manufactured to connect joists and purlins to supporting wood members. They are generally available for member sizes from 38 x 89mm (2" x 4") joists to 89 x 377mm (4" x 14") purlins or double joists. Joists and purlin hangers are made from light gauge galvanized sheet metal and are affixed to wood members with special nails. As with framing anchors, the required number of nails must be used to provide the load-carrying capacity. Hangers can reduce the overall depth of a floor or roof assembly or increase clearance below the framing where joists abut headers rather than rest on top of them.

Space Advantage of Joist Hangers

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Post caps Post anchor

Straps Nail-on plates

H-clip Back-up gypsum wallboard clip

5.8. Adhesives Adhesives play a prominent role in wood construction. They are used for:

• The manufacture of laminated products • As a means of increasing the structural rigidity of sheathing/joist combinations in

floors and of affixing non-structural panel products • End joining dimension lumber • Repair

5.8.1. Adhesives Used for Laminated Products

Structural composites such as plywood, oriented strandboard (OSB) and wafer-board, prefabricated wood I-joists, laminated parallel strand lumber (PSL), laminated veneer lumber (LVL) and glulam are dependent upon adhesives to transfer the stresses between

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adjoining wood fibres. Interior use wood products such as particleboard, which is used for furniture and for some structural applications such as flooring underlay, and hardwood plywood, which is used for furniture and decorative panelling, also rely on adhesives for laminating wood material. The selection, application rate, and curing conditions for adhesives for these products is controlled at the point of manufacture. A brief discussion of the principal adhesives used in these products is presented to address questions which some times arise about permanence of bond, reliability, resistance to environmental factors, and emission of volatile chemicals into buildings. There are two principle types of adhesive used for the manufacture of wood products. These are urea-formaldehyde (UF) which is suitable only for interior use products and phenol-formaldehyde (PF) which is used for exterior applications.

5.8.2. Interior Wood Products

Urea-formaldehyde adhesive is thick creamy syrup which cures to a colourless solid. UF adhesives are very economical and fast curing but are not suitable for damp conditions. For this reason, UF glues are used for panels intended for nonstructural use such as particleboard and hardwood plywood. UF adhesives are non-staining and therefore have the further advantage of not blemishing the high quality expensive face veneers used for hardwood panels for interior finish applications.The raw materials for UF adhesives are derived from natural gas through the intermediates of ammonia for urea and methanol for formaldehyde.

5.8.3. Exterior Wood Products

Phenol-formaldehyde (PF) adhesives are a dark purple-brown colour and give the dark glue lines associated with products such as plywood and OSB. Known as the phenolics, they are a derivative of crude oil and the principle resins approved for the manufacture of wood products intended for exterior applications. PF adhesives are used for the manufacture of glulam, PSL, LVL, plywood, OSB/ waferboard and for fingerjoining stress graded lumber. PF adhesives are somewhat more expensive than UF adhesives and exhibit lower levels of formaldehyde emissions. Various types of extenders such as walnut shell flour, Douglas fir bark flour, alder bark flour, and wood flour are used to moderate the cost of PF glues, control penetration into the wood fibre, and moderate strength properties to suit the materials being bonded.

Resorcinol-formaldehyde (RF) adhesive is a phenolic substance which is more reactive than the PF adhesives. Being more reactive means that curing is faster and takes place at room temperature and below. Otherwise these glues have the same basic properties as the PF adhesives. However, high cost of the resorcinols means in practice that they are often blended with the PF adhesives to moderate the cost.

5.9. General Guidelines for Connections

• Standardize fasteners on a project to speen installation and to reduce the chances of error.

• Select a fastener material or finish which suits the moisture conditions. • Design connection details to accomodate seasoning effect as moisture level in the

wood product adjusts to the building environment. • Specify a finished appearance which suits visual prominance of the fasteners.

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• Connection design must respect wood end and edge distance setbacks to ensure adequacy.

• Connection design must provide stipulated distances between connectors. Ensure that adequate wood material remains after boring for connectors to transfer forces.

• Fastener capacity varies with the inservice moisture content of wood. Most building applications will be for dry service conditions which give good fastener capacity values.

6. References S.Nami Kartal, Harold H. Burdsall Jre, Frederick Green III, 2003, The International Research Group On Wood Preservation, Accidental mold/termite testing of high density fibreboard (HDF) treated with borates and N’N naphthaloylhydroxylamine (NHA); Xiping Wang, Robert J. Ross, Brian K. Brashaw, Steven A. Verhey, John W. Forsman, John R. Erickson, Flexural Properties of Laminated Veneer Lumber Manufactured From Ultrasonically Rated Red Maple Veneer , A Pilot Study; A. Ramirez-Coretti, C.A. Eckelman, R.W. Wolfe, April 1998, Composites and Manufactured Products, Inorganic-Bonded Composite Wood Panel Systems For Low-Cost Housing, A Central American Perspective; Cranswick, Chad J., McGregor, Stuart I., Dowel Connections in Laminated Strand Lumber, University of British Columbia, Vancouver, Canada; California Department of General Services, Division of the State Architect, Product Acceptance Report, Structural Composite Lumber Laminated Strand Lumber (LSL), PA-049; Richard P. Vlosky, Qinglin Wu, Working Paper #46, Louisiana Forest Products Laboratory, Louisiana State University Agricultural Center, Baton Rouge, LA, 2001, An Exploratory Study of the Use of Lumber, OSB, Plywood, LVL, PSL AND LSL, As Raw Materials in the Furniture and Cabinet Industries in the Southern United; Andrzej M. Krzysikjames H. Muehljohn A. Youngquist Fabio Spina Franca, Composites and Manufactured Products, Medium Density Fiberboardmade from Eucalyptus Saligna, Forest Products Journal Vol. 51, No. 10 ; Mariano Martínez Espinosaa, Carlito Calil Jr. Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos – SP, Brazil Escola de Engenharia de São Carlos, Universidade de São Paulo, São Carlos – SP, Brazil, 2000, Statistical Fatigue Experiment Design in Medium Density Fibreboard; Melissa G. D. Baumann, Linda F. Lorenz, Stuart A. Batterman, Guo-Zheng Zhang, Composites and Manufactured Products, Aldehyde Emissions from Particleboard and Medium Density Fibreboard Products, Forest Products Journal Vol. 50, No. 9; Building Standards, Saskatchewan Municipal Affairs, Preserved Wood Foundations;

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Trus Joist, A Weyerhaeuser Business, Boise, ID, Structural Composite Wood Bridges made of Parallam® PSL; Green seal, October 2001, Particleboard and Medium-Density Fiberboard; From Forest to Furniture, march/april 1999, Environmental Design & Construction; Boxler, The Floor for Life Magazine; Sonae Indústria, Growing With Market Needs; Panel guide, annex 2B, OSB (Oriented Strand Board); Georgia-Pacific, Another Do It Yourself Project-Cabinet, Medium Density Fiberboard (MDF) Panels; Laminex group, Particleboard, The Tradesman’s Essential Guide; Kronospan Ltd, A New Practice Case Study-Environmental Technology Best Practice Programme, Membrane Technology Turns Effluent Into Cost Savings; Catalogue no. 36-003-XIB, December 2004, Particleboard, Oriented Strandboard and Fibreboard; FEMA 232, Homebuilders’ Guide, Chapter 6, Roof-Ceiling Systems;