Anatomy of Wood

• Wood is a fibrous cellular substance.

Bark

• It is the exterior covering of a tree.
• Bark contains an inner living layer called phloem.

Cambium

• A thin layer of reproductive tissue is situated between the phloem and xylem.

Phloem

• The tissue carries food from leaves to the growing parts of the tree.

Xylem

• This woody tissue supports the tree and transports food upward from the roots.

Sapwood/Alburnum

• This is the younger, softer, living part of the wood.
• It is found between the cambium and heartwood.

Heartwood/Duramen

• This is the older, harder, inactive core of the wood.
• The heartwood is darker in color.

Medullary rays/Pith rays

• Ribbons of tissue extend radially from the pith.
• They transport food horizontally.

Annual ring/Growth ring

• Concentric rings form annually within the wood.

Pith

• This is the soft central core of a tree.

Hardwood/Deciduous

• Known for broad leaves.
• Flower-bearing trees.
• Trees shed annually.

Softwood/Conifer/Evergreen

• Characterized by pine leaves.
• Cone bearing trees.
• Foliage remains year-round.

Exogenous growth

• Grows outward.
• Preferred in lumbering.

Endogenous growth

• Grows inward.
• Not preferred in lumbering.

Decay - Wood Defect

• Decomposition due to fungi.

Dry Rot - Wood Defect

• Decay of seasoned timber.

Check - Wood Defect

• Separation across the annual rings.

Shake - Wood Defect

• Separation along the grain of the wood.

Pitch Pocket - Wood Defect

• A well-defined opening between annual rings.

Split/Through Check - Wood Defect

• A check that extends completely through a veneer.

Knot - Wood Defect

• The base of a wooden branch.

Types of Knots - Wood Defect

• Sound Knot: Solid across its face and undecayed.
• Live Knot: Annual rings intergrown with wood.
• Tight Knot: Held firmly in place.
• Dead Knot: Can easily loosen or be knocked out.

Wane - Wood Defect

• The presence or absence of wood at a corner.

Skip - Wood Defect

• When missing a spot caused by the planning machine.

Machine Burn - Wood Defect

• Surface charring.

Types of Warp - Wood Defect

• Warp: Any deviation from a true plane or surface.
• Cup: Curvature across the width/face of a wood.
• Bow: Curvature along the length of a wood.
• Crook: Curvature along the edge of a wood.
• Twist: Turning edges in opposite directions.

Types of Lumber

• Lumber: Wood after being sawed/sliced into commercial boards, planks, or sticks.
• Rough Lumber: Lumber that is not surfaced.
• Dressed Lumber: Lumber that has been surfaced.
• Surfaced Green: Dressed lumber with moisture exceeding 19%.
• Surface Dry: Dressed lumber with 19% or less moisture content.

Nominal Dimension

• The dimension before drying and surfacing.

Dressed Size

• Dimensions after drying and surfacing.
• Typically 3/8 - 3/4 less than the nominal size.

Grade

• Classification of lumber regarding strength and utility.

Yard Lumber

• Hardwood lumber.
• Used for general building purposes.

Classification of Yard Lumber

• Board: Thickness <2", width >2".
• Dimension lumber: Thickness 2"-4", width 2"+.
• Timber: Thickness 5"+, width 5"+.
• Slab: Rough lumber cut tangent to annual rings.
• Plank: Thickness 2" - 5", wide.
• Flitch: A thick piece of lumber.

Dimension Lumber Sizes

• Light Framing: Non-high strength lumber with thickness 2"-4" and width 2"-4".
• Decking: Lumber loaded on the wide face, thickness 2"-4", width 4"+.
• Joists & Planks: Lumber loaded on the narrow face, thickness 2"-4", width >4".

Timber

• Beams & Stringers: Made of structural lumber (thickness 5"+, width 5"+2").
• Post & Timbers: Made of structural lumber (thickness 5", width 5", and not more than 2” greater than the thickness).

Seasoning

• Also known as conditioning or curing, is the process of removing moisture from wood.

Methods of Seasoning Lumber

• Natural Methods: Air Drying and Sun Drying.
• Artificial Methods: Kiln Drying, Pressure Drying, Vapor Drying, and Radio Frequency Dielectric Drying.

Plywood

• Made by bonding veneers under heat and pressure.
• Veneers are aligned at right angles to each other

Types of Plywood

• Ordinary, Marine, Form, Fancy, and Pre-finished Plywood Paneling.

Particle Board

• A non-veneered wood panel bonds small wood particles under heat & pressure.

Chipboard

• A class of building board made from wood and particles with veneer.
• Chipboards are bonded by phenol resin/urea formaldehyde glue.
• An improved version of particle board.

Wafer Board

• Non-veneered.
• Large thin wood flakes are bonded under heat and pressure with waterproof adhesive.
• Not structural.

Fiber Board

• Made of wood or other plant fibers compressed with a binder into rigid sheets.
• An improved version of hard board.

Hard Board

• A very dense, felted, homogenous panel made under heat & pressure.

Kinds of Hard Board

• Standard Hard Board: Flexible and easily bent.
• Tempered Hard Board: Baking and impregnating standard hard board.
• Low-Density Hard Board: Low density and lightweight.

Tempered Board

• Hardboard is impregnated & baked to improve hardness & moisture resistance.
• Treated hardboard.

Oriented Strandboard

• Non-veneered
• Commonly used for subflooring.
• Consists of 3-5 layers of long thin wood strands bonded via heat and pressure using a waterproof adhesive.
• A structural version of wafer board.

Parallel Strandboard/Lumber

• Structural lumber.
• Bonding long, narrow wood strands together under heat & pressure.
• Used as beams & columns.

Peg Board/Perforated Board

• Tempered board having regularly spaced perforations.

Straw Board

• Hardboard, compressed with wheat straw, and covered with tough kraft paper.

Grades of Strawboards

• Structural Board Grade
• Insulation Grade

Structural Glue-Laminated Timber

• An assembly of lumber laminations with grain approximately parallel longitudinally.
• Glued with adhesives.

Cork Board

• Made from cork granules mixed with synthetic resin, compressed and formed into sheets.

Asbestos Cement Board

• A dense, rigid board made from a high percentage of fibers bonded with Portland cement.
• High fire resistant, low heat flow resistance.
• Also Known as FICEM (fiber cement) board.

Gypsum Board

• A wall board having a gypsum core.

Standard Size of Boards

• SURFACE = 4’ X 8’
• THICKNESS
  • – 1/8” (3MM) - BACKING
  • – ¼” (6MM) - CEILING
  • – ½” (12MM) - WALL PARTITIONS
  • – ¾” (19MM) - CABINETRY
  • – 1” (25MM) - CABINETRY / STRUCTURAL PARTITIONS