Wood and Wood-Based Products: Lumber, Panels, and Fasteners

Plastic Lumber

  • Composed of greater than 50%50\% plastic.

  • Used in both finish and structural applications.

  • Possesses characteristics of durability, being maintenance-free, and resistance to decay.

  • Limitations: Similar to Wood Plastic Composites (WPCs), plastic lumber is more flexible than solid wood, necessitating support at more closely spaced intervals.

  • Thermal Movement: It exhibits greater expansion and contraction with temperature fluctuations, requiring increased allowances for thermal movement during installation.

Wood Panel Products

  • Standard Dimensions: Panels typically measure 4 by 8 feet (4 \text{ by } 8 \text{ feet } (1220 \text{ by } 2440 \text{ mm}).</p></li><li><p><strong>StrengthDistribution</strong>:Panelsoffermorenearlyequalstrengthintheirtwoprincipaldirectionscomparedtosolidwood,whichhasdistinctgrain−orientedstrengthdifferences.</p></li><li><p><strong>ReducedDefects</strong>:Issuessuchasshrinking,swelling,checking(smallcracks),andsplittingaresignificantlyreducedinpanelproducts.</p></li><li><p><strong>ResourceEfficiency</strong>:Theyrepresentamoreefficientuseofforestresourcesthansolidwoodproducts.</p></li><li><p><strong>CommonApplications</strong>:Widelyusedassheathingonframedwallsandroofs,andassubflooringoverfloorframing.</p></li></ul><h4id="f885d196−35b8−4ca4−86b6−e49da635ced4"data−toc−id="f885d196−35b8−4ca4−86b6−e49da635ced4"collapsed="false"seolevelmigrated="true">StructuralWoodPanels</h4><h5id="ea4434f4−eda0−43b7−bf99−7daae89ee84b"data−toc−id="ea4434f4−eda0−43b7−bf99−7daae89ee84b"collapsed="false"seolevelmigrated="true">Plywood</h5><ul><li><p><strong>Composition</strong>:Madefromlaminatedsoftwoodveneers.</p></li><li><p><strong>LayerStructure</strong>:TypicallyconsistsofmultiplelayersincludingaFACE,CROSSBANDS,CORE,CROSSBANDS,andaBACKlayer,withgrainorientationalternatinginsuccessivepliesfordimensionalstabilityandbalancedstrength.</p></li></ul><h5id="8667bd0a−7652−4f34−964c−c6939ebc4926"data−toc−id="8667bd0a−7652−4f34−964c−c6939ebc4926"collapsed="false"seolevelmigrated="true">OrientedStrandBoard(OSB)</h5><ul><li><p><strong>Composition</strong>:Fabricatedfromlongshreds(strands)ofwoodthatarecompressedandgluedtogetherintothreetofivelayers.</p></li><li><p><strong>Comparison</strong>:SimilarinconcepttoLaminatedStrandLumber(LSL)duetoitsuseofstrands.</p></li><li><p><strong>StrengthandStiffness</strong>:Duetothesubstantiallengthandcontrolledorientationofitsstrands,OSBisrecognizedasthestrongestandstiffesttypeofnon−veneeredpanelproduct.</p></li></ul><h5id="a0d42f65−8024−469f−a5f5−5d8c6e5da27f"data−toc−id="a0d42f65−8024−469f−a5f5−5d8c6e5da27f"collapsed="false"seolevelmigrated="true">Fiberboard</h5><ul><li><p><strong>Composition</strong>:Consistsofveryfine−grainedwoodparticles.</p></li><li><p><strong>Applications</strong>:Generallyrestrictedtointeriorusesduetoitscompositionandsusceptibilitytomoisture.</p></li><li><p><strong>ManufacturingProcess</strong>:Itsproductionprocessismoreintensivecomparedtothemanufactureofparticleboard.</p></li></ul><h5id="eb6f1456−6f0b−45f6−8cb2−03e57f07a910"data−toc−id="eb6f1456−6f0b−45f6−8cb2−03e57f07a910"collapsed="false"seolevelmigrated="true">OtherPanelTypes</h5><ul><li><p><strong>Compositepanels</strong>:Featurefaceveneersbondedtoasolidcorematerial.</p></li><li><p><strong>Particleboard</strong>:Composedofgluedparticles;theseparticlesaresmallerthanthestrandsfoundinOSBbutlargerthanthefineparticlesusedinfiberboard.</p></li></ul><h4id="ac08a51d−b0f9−4907−90ab−dddbea4d5916"data−toc−id="ac08a51d−b0f9−4907−90ab−dddbea4d5916"collapsed="false"seolevelmigrated="true">SpecifyingStructuralPanels</h4><h5id="4b844a56−8dd9−4c50−9009−764ea1cd2cee"data−toc−id="4b844a56−8dd9−4c50−9009−764ea1cd2cee"collapsed="false"seolevelmigrated="true">SpanRating</h5><ul><li><p><strong>Definition</strong>:Anumericaldesignationindicatingapanel′ssuitabilityforspecificframingspanswhenusedasroofsheathingorsubflooring.</p></li><li><p><strong>Example</strong>:Apanelwithaspanratingof).</p></li><li><p><strong>Strength Distribution</strong>: Panels offer more nearly equal strength in their two principal directions compared to solid wood, which has distinct grain-oriented strength differences.</p></li><li><p><strong>Reduced Defects</strong>: Issues such as shrinking, swelling, checking (small cracks), and splitting are significantly reduced in panel products.</p></li><li><p><strong>Resource Efficiency</strong>: They represent a more efficient use of forest resources than solid wood products.</p></li><li><p><strong>Common Applications</strong>: Widely used as sheathing on framed walls and roofs, and as subflooring over floor framing.</p></li></ul><h4 id="f885d196-35b8-4ca4-86b6-e49da635ced4" data-toc-id="f885d196-35b8-4ca4-86b6-e49da635ced4" collapsed="false" seolevelmigrated="true">Structural Wood Panels</h4><h5 id="ea4434f4-eda0-43b7-bf99-7daae89ee84b" data-toc-id="ea4434f4-eda0-43b7-bf99-7daae89ee84b" collapsed="false" seolevelmigrated="true">Plywood</h5><ul><li><p><strong>Composition</strong>: Made from laminated softwood veneers.</p></li><li><p><strong>Layer Structure</strong>: Typically consists of multiple layers including a FACE, CROSSBANDS, CORE, CROSSBANDS, and a BACK layer, with grain orientation alternating in successive plies for dimensional stability and balanced strength.</p></li></ul><h5 id="8667bd0a-7652-4f34-964c-c6939ebc4926" data-toc-id="8667bd0a-7652-4f34-964c-c6939ebc4926" collapsed="false" seolevelmigrated="true">Oriented Strand Board (OSB)</h5><ul><li><p><strong>Composition</strong>: Fabricated from long shreds (strands) of wood that are compressed and glued together into three to five layers.</p></li><li><p><strong>Comparison</strong>: Similar in concept to Laminated Strand Lumber (LSL) due to its use of strands.</p></li><li><p><strong>Strength and Stiffness</strong>: Due to the substantial length and controlled orientation of its strands, OSB is recognized as the strongest and stiffest type of non-veneered panel product.</p></li></ul><h5 id="a0d42f65-8024-469f-a5f5-5d8c6e5da27f" data-toc-id="a0d42f65-8024-469f-a5f5-5d8c6e5da27f" collapsed="false" seolevelmigrated="true">Fiberboard</h5><ul><li><p><strong>Composition</strong>: Consists of very fine-grained wood particles.</p></li><li><p><strong>Applications</strong>: Generally restricted to interior uses due to its composition and susceptibility to moisture.</p></li><li><p><strong>Manufacturing Process</strong>: Its production process is more intensive compared to the manufacture of particleboard.</p></li></ul><h5 id="eb6f1456-6f0b-45f6-8cb2-03e57f07a910" data-toc-id="eb6f1456-6f0b-45f6-8cb2-03e57f07a910" collapsed="false" seolevelmigrated="true">Other Panel Types</h5><ul><li><p><strong>Composite panels</strong>: Feature face veneers bonded to a solid core material.</p></li><li><p><strong>Particleboard</strong>: Composed of glued particles; these particles are smaller than the strands found in OSB but larger than the fine particles used in fiberboard.</p></li></ul><h4 id="ac08a51d-b0f9-4907-90ab-dddbea4d5916" data-toc-id="ac08a51d-b0f9-4907-90ab-dddbea4d5916" collapsed="false" seolevelmigrated="true">Specifying Structural Panels</h4><h5 id="4b844a56-8dd9-4c50-9009-764ea1cd2cee" data-toc-id="4b844a56-8dd9-4c50-9009-764ea1cd2cee" collapsed="false" seolevelmigrated="true">Span Rating</h5><ul><li><p><strong>Definition</strong>: A numerical designation indicating a panel's suitability for specific framing spans when used as roof sheathing or subflooring.</p></li><li><p><strong>Example</strong>: A panel with a span rating of32/16meansitcanbeutilizedasroofsheathingoverraftersspacedmeans it can be utilized as roof sheathing over rafters spaced32 \text{ inches } (813 mm813 \text{ mm}) apart, or as subflooring over joists spaced 16 inches (16 \text{ inches } (406 \text{ mm})apart.</p></li></ul><h5id="0e4ae4dc−b237−4115−b60b−216454c33b78"data−toc−id="0e4ae4dc−b237−4115−b60b−216454c33b78"collapsed="false"seolevelmigrated="true">BondClassifications</h5><ul><li><p><strong>ExteriororExposure1</strong>:Thisisthemostcommonclassification.</p><ul><li><p><strong>ExposureDurabilityClassification</strong>:DesignatedasExposure1.</p></li><li><p><strong>AdhesiveType</strong>:Utilizesexteriorglue,providingenhancedresistancetomoisture.</p></li><li><p><strong>VeneerQuality</strong>:Typicallymadewithmediumqualityveneers.</p></li><li><p><strong>IntendedUse</strong>:Primarilyforinteriorapplications.</p></li><li><p><strong>MoistureTolerance</strong>:Allowsforprolongedexposuretomoistureduringtheconstructionphasewithoutcompromisingstructuralintegrity.</p></li></ul></li></ul><h4id="88a63766−e6e6−4ffc−bc09−421f7a31e3b9"data−toc−id="88a63766−e6e6−4ffc−bc09−421f7a31e3b9"collapsed="false"seolevelmigrated="true">PlywoodVeneerGrades</h4><ul><li><p><strong>GeneralPrinciple</strong>:Lowergrades(e.g.,D)inherentlyexhibitmoredefectsthanhighergrades.</p></li><li><p><strong>GradeA</strong>:Smoothandpaintablesurface.Permitsnomorethan) apart.</p></li></ul><h5 id="0e4ae4dc-b237-4115-b60b-216454c33b78" data-toc-id="0e4ae4dc-b237-4115-b60b-216454c33b78" collapsed="false" seolevelmigrated="true">Bond Classifications</h5><ul><li><p><strong>Exterior or Exposure 1</strong>: This is the most common classification.</p><ul><li><p><strong>Exposure Durability Classification</strong>: Designated as Exposure 1.</p></li><li><p><strong>Adhesive Type</strong>: Utilizes exterior glue, providing enhanced resistance to moisture.</p></li><li><p><strong>Veneer Quality</strong>: Typically made with medium quality veneers.</p></li><li><p><strong>Intended Use</strong>: Primarily for interior applications.</p></li><li><p><strong>Moisture Tolerance</strong>: Allows for prolonged exposure to moisture during the construction phase without compromising structural integrity.</p></li></ul></li></ul><h4 id="88a63766-e6e6-4ffc-bc09-421f7a31e3b9" data-toc-id="88a63766-e6e6-4ffc-bc09-421f7a31e3b9" collapsed="false" seolevelmigrated="true">Plywood Veneer Grades</h4><ul><li><p><strong>General Principle</strong>: Lower grades (e.g., D) inherently exhibit more defects than higher grades.</p></li><li><p><strong>Grade A</strong>: Smooth and paintable surface. Permits no more than18neatlymaderepairs(suchasboat,sled,orrouter−type)whichmustbeparalleltothegrain.Bothwoodorsyntheticrepairsareallowed.Canbeusedfornaturalfinishesinlessdemandingapplications.</p></li><li><p><strong>GradeB</strong>:Solidsurface.Allowsforshims,sledorrouterrepairs,andtightknotsuptoneatly made repairs (such as boat, sled, or router-type) which must be parallel to the grain. Both wood or synthetic repairs are allowed. Can be used for natural finishes in less demanding applications.</p></li><li><p><strong>Grade B</strong>: Solid surface. Allows for shims, sled or router repairs, and tight knots up to1 \text{ inch}acrossthegrain.Woodorsyntheticrepairsarepermitted.Someminorsplitsmaybepresent.</p></li><li><p><strong>GradeCPlugged</strong>:AnimprovedCveneergrade.Splitsarelimitedtoacross the grain. Wood or synthetic repairs are permitted. Some minor splits may be present.</p></li><li><p><strong>Grade C Plugged</strong>: An improved C veneer grade. Splits are limited to1/8 ext{-inch}width,andknotholesorotheropendefectsarerestrictedtowidth, and knotholes or other open defects are restricted to1/4 \text{ x } 1/2 \text{ inch}.Woodorsyntheticrepairsareallowed.Itadmitssomebrokengrain.</p></li><li><p><strong>GradeC</strong>:Featurestightknotsupto. Wood or synthetic repairs are allowed. It admits some broken grain.</p></li><li><p><strong>Grade C</strong>: Features tight knots up to1-1/2 \text{ inch}.Knotholesarepermittedupto. Knotholes are permitted up to1 \text{ inch}acrossthegrain,withsomealloweduptoacross the grain, with some allowed up to1-1/2 \text{ inch}ifthetotalwidthofknotsandknotholesremainswithinspecifiedlimits.Syntheticorwoodrepairsarepermitted.Discolorationandsandingdefectsthatdonotimpairstrengthareacceptable.Limitedsplitsandstitchingareallowed.</p></li><li><p><strong>GradeD</strong>:Allowsforknotsandknotholesuptoif the total width of knots and knotholes remains within specified limits. Synthetic or wood repairs are permitted. Discoloration and sanding defects that do not impair strength are acceptable. Limited splits and stitching are allowed.</p></li><li><p><strong>Grade D</strong>: Allows for knots and knotholes up to2-1/2 ext{-inch}widthacrossthegrain,andwidth across the grain, and1/2 \text{ inch}$$ larger within specified limits. Limited splits and stitching are permitted. This grade is typically restricted to Exposure 1 or Interior panels due to its higher defect allowance.

Wood Chemical Treatments

Fire-Retardant Treated Wood

  • Process: Wood is pressure-impregnated with chemical salts.

  • Purpose: These chemicals are designed to reduce the wood's combustibility.

  • Application: Primarily used in construction scenarios where building codes impose restrictions on the use of combustible materials.

Preservative-Treated Wood

  • Purpose: To safeguard wood against decay from fungi and insect attack.

  • Application: Essential for wood components exposed to the weather, in direct contact with the ground, or situated in areas identified with a high risk of termite infestations.

Types of Preservative-Treated Wood

  • Process: Pressure impregnation is the method used, which effectively drives the preservative chemicals deeply into the wood fibers, resulting in what is commonly known as