Plywood

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Contents 1 Material analysis 1.1 History 1.2 Traditional uses 1.3 Emerging uses / trends 1.4 Finish and aesthetic qualities 1.5 Surface forms / shapes 1.6 Cost analysis 2 Material properties 2.1 Primary structural use 2.2 Benefits of plywood 2.3 Types of plywood 2.4 Dimensional and opening restriction 2.5 Acoustic property 2.6 Manufacturing process and assembly 3 Environmental impact 3.1 LEED 4 Health Effects 5 Life Safety & Rating Standards 5.1 Flammability rating 5.2 Coefficient of friction 6 References 6.1 Notes 6.2 Student contributions 7 See also 7.1 Similar materials 8 External links 8.1 Additional resources 8.2 Leading manufacturers

Material analysis

MasterFormat 06055:

History

• Dated back approximately in the 1500 B.C. when Egyptian craftsman would use bonded thin pieces of wood for their pharoah's tombs.
• In the 1600s, the term veneering was derived from craftsmen decorating furnitures using thin pieces of wood.
  • The term veneers is known as the thin pieces of wood.

Traditional uses

• Used as applied material in construction for simple structures.
• Acts as a substrate for other materials in a typical interior or exterior environment.

Emerging uses / trends

• Bent formed furniture.
• Applications of stained and bent interior finishes.
• Flooring
• Framing
• Sheer walls
• Joinery products

Finish and aesthetic qualities

• Comes in wide variety of wood species.
  • Species group number range from 1 to 5 with wood from the species of tress in group 1 being the strongest and stiffest, e.g. beech, and 5 being the lest stiff and strong, e.g. basswood or poplar.
• Aesthetics depend on quality of the veneer material and type of grain/cut.
  • Veneer grades rated N, A, B, C or D with N being the highest quality and D the lowest according to degree of knots, splits and stitching permitted.
  • A pair of veneer grades, such as “A-B” indicate that one side is rated A and the other side B.
• Sanded, unsanded, and stained finishes available.

Surface forms / shapes

• Industry standard dimensions available that can be custom cut and/or bent.

Cost analysis

• Price / SqFt: varies depending on thickness and grade of wood veneer as well as interior or exterior applicaton.
• Price ranges from basic to best quality
  • Plywood Siding Prices (Material Only): $2,036-$3,381
  • Plywood Siding Installation Cost: $1,103-$1,662
  • Plywood Siding – Total: $3,139-$5,043
  • Plywood Siding Average Cost per square foot: $3.07-$4.11

Material properties

Primary structural use

• Compression and applied to construction e.g. as a substrate.

Benefits of plywood

• Strong & Flexible
• Increased stability
• High/impact resistance
• Surface dimensional stability
• High strength to weight ratio
• Panel shear
• Chemical resistance

Types of plywood

• Veneer Core:
  • Thickness (1/8in. to 3/4in.)
  • Composed with odd number plies
  • Center (Middle ply)
  • Cross Bandings (Either side of center)
  • Faces & Backs (Outter plis)
• Patricle Board/ Fibreboard Core:
  • Face and back are directly placed to the particleboard.
• Composite Core:
  • The veneer core is combined with the composite crossband
  • Smooth surface of fibreboard core

Dimensional and opening restriction

• Standard thickness of 1/4” - 1 1/4”.
• Typical sheet sizes of 4’x8’ and 4’x10’.
• Other sizes are manufactured in 12” increments of 36”, 48” and 60” and in 9ft lengths.
• Openings to be framed with joists or studs depending on application.
• Sanded panels range in thickness from 1/4” to 1 1/4” or more in steps of 1/8”.
• Unsanded panels range from 5/16” to 1 1/4” or more.
• Custom shapes can be cut from standard panel sizes.

Acoustic property

• Plywood is utilized for acoustical control due to its absorptive qualities.
• Perforated or slotted plywood panels are available for increased acoustical control.

Manufacturing process and assembly

• Plywood is an engineered wood, or composite material, made from thin sheets of wood veneer or plies. Plies are stacked together with the direction of each ply’s grain differing from its neighbors’ by 90° cross banding. Plies are bonded under heat pressure with strong adhesives. It is more resistant to cracking, shrinkage, twisting/warping and in general has a higher degree of strength than plain wood.
• Trees used to manufacture plywood are smaller in diameter

• Step 1: Log processing and log conditioning
  • Log are debarked and cut into sections about 8ft-4 in (2.5m) to 8 ft-6in (2.6m) long.
  • Veneer is dried in stream or gas heated ovens for about 12 to 40 hours depending on the type of wood to soften the wood.
• Step 2: Lathing
  • At the lathe, a blade repeatedly peels the log into a long sheet of veneer
• Step 3 : Veneer application
  • The sheet of veneer is then stored or can be processed right away.
• Step 4: Veneer coating
  • Waterproof glue coats the veneers and the coated veneers are placed into sandwiches
• Step 5: Curing
  • The veneer sandwiches are exposed to heat and pressure by placing them in the hot press until the glue is cured
• Step 6: Grade Selection
  • The plywood panels are trimmed, then cut into squared and are chosen by grade

• 1/8” spacing on installed panels is recommended to allow for expanding and contracting of panels according to varying moisture and temperature conditions. This will minimalizes buckling of panels.

Environmental impact

• Production of synthetic resins used in plywood manufacture is energy consuming:
  • Energy is used in cutting and pressing the veneers.
  • Many plywoods are imported so have energy costs from transportation.
• Plywood is more efficient in use than sawn timber with some wood species yielding up to 90% usable veneers.
• Formaldeyde resins are the most common bonding agent used to produce the plywood and will offgas.
• Burning plywood may release harmful gases such as hydrogen cyanide from the resins.
• Manufacturers may adhere to Sustainable Forest Initiative (SFI), Forest Stewardship Council (FSC) and Smart Wood certified forestry, which set principles integrating perpetual growing and protection of wildlife, plants, soil and water quality.

LEED

• Plywood that is formaldehyde-free is compliant with LEED standards, helping earn one point for LEED’s EQ Credit 4.4 for Low-Emitting Materials: Composite Wood.

Health Effects

• Volatile Organic Compounds (VOC) are a variety of different chemicals and gasses emitted from different solids or liquids that can cause both long and short term health effects.
• Plywood and particle board are bounded by adhesives that have urea-formaldehyde resins.
  • This type of chemical is a colourless, pungent gas that releases over time.
• Formaldehyde is used in many household products.
• If the user is exposed to formaldehyde for a period of time, he/she may get
  • Watery eyes
  • Burning sensations in the eyes and throat
  • Nausea
  • Difficulty in breathing
  • High concentrations may trigger attacks in people with asthma
  • Cancer

Life Safety & Rating Standards

Flammability rating

• Fire retardant treatments available through coating or impregnation of material. Note that some fire retardant coated material does not meet code requirements for structural uses.
• Plywood fire retardant treated construction standards of 0-25 Flame Spread Rating, Class I.

Coefficient of friction

References

Notes

• The Engineered Wood Assoc.
• How Products Are Made
• EPA United States Environmental Protection Agency
• Fine Lumber
• Homewyse
• Canadian Plywood Association
• * Veneer Solutions. Reston, VA: Architectural Woodwork Institute, 1998.

Student contributions

• Nico Flannery, Fall 2005
• Michelle Aberbach, Spring 2008

See also

Similar materials

• Particle Board
• Fiber Board
• Palm Plywood

External links

Additional resources

• Boulter Plywood (Local Resource)

Leading manufacturers

• Rosboro
• Patriot Timber
• The Wood & Shop, Inc.
• link Clarke Veneers & Plywood