1 wood and plastics. 2 major topics classification of wood  hardwood  softwood growth of wood...

Download 1 Wood and Plastics. 2 Major Topics Classification of Wood  Hardwood  Softwood Growth of Wood Wood Defects Wood (Lumber)  Seasoning/Kiln Drying  Moisture

Post on 11-Jan-2016




1 download

Embed Size (px)


  • Wood and Plastics

  • Major TopicsClassification of WoodHardwoodSoftwoodGrowth of WoodWood DefectsWood (Lumber)Seasoning/Kiln DryingMoisture ContentCutting

  • Major Topics contWood (Lumber)Decay/InsectsGradingSizing (Nominal vs. Actual)JointsFastenersPrefabricated Wood (Glue-laminated)

  • Major Topics contPlywoodOther PanelsWaferboardCompositeParticleboardOSB (Oriented Strand Board)Plastics

  • Classification of WoodHardwood trees which are deciduous (shed broad shaped leaves annually) ex: Birch, Ash, Maple, OakUses: flooring, interior paneling, cabinets & furniture

    Softwood trees which are evergreen (needle-like leaves) ex: Southern Pine, Fir, Spruce, Redwood75% of lumber produced is made of softwoodUses: structural framing lumber, sheathing, roofing, and exterior siding

  • Growth of WoodGrowth is formed from core (pith) in rings. The # of rings and spacing between rings show age and growing conditions of tree.Wood is made of hollow tubular cells running parallel to the long axis of the tree.

  • Wood DefectsCommon defects include: knots, stain, pitch pockets, decay, and cracks.These defects will impact the visual grading of wood products

  • Examples of DefectsKnotWane irregular rounding caused by cutting too close to outside of logResin Pocket

  • LumberBroad term that applies to all finished or semi-finished wood shaped with parallel longitudinal surfacesNominal piece sizing includes:Board -- 11/2 or less thick and 2 or more wideDimension 2 to 5 thick and >2 wideTimbers -- 5 or more thick and wide

  • Lumber Measured in Board Feethttp://www.woodzone.com/tips/board_feet/board_feet.htmSee page 330 Section for explanation on how to calculate board feet

  • Pop Quiz provide answers to the following:What is the standard unit of measure for lumber?Calculate the board feet in a 2 x 4 stud 8-0 long Find the board feet in 60 pieces of 2 x 10 joists 14 feet long.

  • Pop Quiz Answers1.Board feet

    2.(Thickness [in] x Width [in] x Length [in])/144 = Board Feet (2 x 4 x [8 x 12])/144 = Board feet(8 x 96)/144 = Board feet(768)/144 = Board feet5.3 Board feet (rounded off)ORThickness (in) x Width (ft) x Length (ft) = Board Feet2 x 4/12 x 8 = Board feet2 x .333 x 8 = Board feet5.3 Board Feet (rounded off)

    3.Number of pieces x Thickness (in) x Width (ft) x Length (ft) = Board Feet60 x 2 x 10/12 x 14 = Board feet60 x 2 x .833333 x 14 = Board feet1400 = Board feetOften written as 1.4 MBM [1.4 Thousand Board Measure]

  • Seasoning/Kiln DryingSeasoning- the process of reducing moisture until a suitable level is achieved (causes shrinking in lumber size)May be seasoned in the air (2-6 months for softwood and may take 4 years for some hardwoods) or by using a kilnA chemical (hygroscopic) may be applied to the wood to keep surface moist to reduce shrinkage cracks (checks)

  • Moisture ContentThe strength of wood increases as the moisture content (m.c.) decreasesM.C. varies depending on the conditions (geographical region & indoor/outdoor) in which the lumber will be usedTypically, m.c. does not exceed 19%

  • CuttingPlain-sawed (flat sawed) lumber which is cut in parallel slides [less waste & cheaper; warps & splits]Edge-sawed lumber which is cut perpendicular to the exterior of the treeQuarter-sawed lumber in which the log is 1st cut into quarters and then cut on the diagonal [produces the most attractive wood grains]

  • Decay-InsectsTermites destroy wood by chewing it (chemical or physical barriers should be used to deter them)Fungi feed on wood fibers leaving wood weakened with rottingAvoid placing untreated wood directly in contact with concrete

  • Pressure-Treated LumberMust meet all EPA (Environmental Protection Agency) requirementsCCA (Chromated Copper Arsenate) was the most widely used until Dec. 2003 no longer produced because of environmental concernsThe current wood preservatives include:ACQ (alkaline copper quat)Copper Azole (CA types A & B)Sodium Borate (SBX)**** Main concern with new products are that they increase the deterioration of fasteners drastically more than CCA did reduce the life expectancy of a structure by a factor of fourSource: CSI March 2004 publication of The Construction Specifier

  • GradingDepends on the appearance ( # of defects) and strengthLumber pieces are marked with a grade stampTypical stamp includesGrading body (WWP Western Wood ProductsMill identificationGrade name (Const construction)Moisture contentType of wood (D-Fir Douglas Fir)See Figs. 6.2-20,-21, and -22 on pages 335-36 for examples of grade marks

  • Sizing (Nominal vs. Actual)Lumber is referred to by nominal size but the actual size is less (see lumber sizes handout)2x4 actually measures 1-1/2 x 3-1 x 8 actually measures x 7-1/4

  • Joints

  • FastenersNails, screws, bolts, staples, anchors, and joist hangers are common fastenersSizes, styles, and finishes (coatings) depend on the intended applicationLength of nails designated in pennies [d]

  • Nails**** There are a variety of nailing methods used: Toe nailing, end nailing, face nailing, blind nailing**** Standard sizes of common wire nailsSee page 361 for Figures 6.6-2and 6.6-3

  • Prefabricated WoodBecause of the limitations of size of sawn wood the gluing of smaller pieces together will enable structural members of virtually any length, cross-section, and desired curves to be madeGlu-lam members are widely used in areas of construction using arches (must comply with ANSI 190.1)

  • GlueLams [Laminated Timbers] See page 405Individual laminations are placed so that:Weak spots are separated from each other to avoid concentration of weaknessAppearance flaws in wood are hidden within the memberEnd joints between lams are separated from each other to avoid a plane of weaknessThe strongest wood is placed where stresses are highest

  • Species of Lumber Used for GlueLamDouglas FirAlaska CedarSpruce-Pine FirSouthern Pine

  • PlywoodPlywood is a type of glued, laminated wood. Thin wood layers of laminations are arranged with the grains of each layer perpendicular to the adjacent one.Veneers the actual laminations consisting of face & back, crossbands, and the inner (core) Usually an odd number of veneers (3-5; may be up to 11)Thickness may range from 1

  • Advantages of Plywood vs. Sawn LumberHas great transverse strength which aids in strengthening/bracing entire structure when used over studs, joists, and rafters for wood frame constructionLess warping and change due to moisture changesIs more easily bent to form curves for concrete forms or curved wood constructionFabricated in large sheets (4x8, typical) which covers larger areas more quicklyCan be worked closer to the edges without splittingDesired appearance can be obtained by using thin veneers of high quality wood where they are visible

  • Grades/Types of Plywood5 basic grades from best to less desirable finished appearance: A, B, C, C plugged, & D [see figs 6.3-5;6 and 6.3-6 on pages 340-2 for grades]5 species groups (according to stiffness and strength): Group 1 is the strongest/stiffestTypes of plywood: interior and exteriorInterior- made with glue suitable for indoor use; available in any gradeExterior made with hot, phenolic resin glue which is unaffected by water & resists weathering; no veneers below C grade used

  • APA Engineered Wood ProductsAPA American Plywood Association key organization for plywood informationWebsite link:http://www.apawood.org/

  • Other PanelsWaferboardCompositeParticleboardOSB (Oriented Strand Board)

  • PlasticsUsually contain synthetic resins. May also contain plasticizers, fillers, and colorants2 basic classes of plastics; thermoplastics (no chemical change during heating/cooling) & thermosetting plastics (change chemically when heated and solidify while still hot)Plastic products are strong, light in weight, formable, and resistant to corrosion

  • Thermoplastics

  • Thermosetting

  • ReferencesConstruction Materials and Processes, 3rd Edition. Watson, Don A.. McGraw-Hill, 1986. Imprint 2000. ISBN: 0-07-068476-6Construction Principles, Materials, and Methods, Seventh Edition. H. Leslie Simmons, John Wiley and Sons, Inc., 2001.Olins Construction Principles, Materials, and Methods, Eighth Edition. H. Leslie Simmons, John Wiley and Sons, Inc., 2007Architectural Materials for Construction, Rosen, Harold J. and Heineman, Tom. McGraw-Hill, 1996. ISBN: 0-07-053741-0Basic Construction Materials, 6th Edition. Marotta, Theodore W. Prentice Hall, 2002. ISBN: 0-13-089625-XBuilding Construction: Materials and Types of Construction, 6th Edition, Ellison, Donald C., Huntington, W.C., Mickadeit, Robert E.. John Wiley & Sons. ISBN: 0-13-090952-1.Architectural Graphic Standards: Student Edition, Abridgment of 9th Edition. The American Institute of Architects. John Wiley & Sons. ISBN: 0-471-34817-1


View more >