Alphabethacal Terms of The Trade ____text in bold____

Backs: The plywood side with the lower grade — which is the back.

BBOES: Stands for B-B plywood; Oiled face & Edge-Sealed edges.

B-B Plyform: Usually a sanded plywood panel with a B-grade face and back and C-grade inner plies. Used in concrete form grades where reuse is of little or no importance.

Blow: A localized delamination caused by steam pressure building up during the hot pressing operation.

Blowout: Term used when ready-mixed concrete breaks through the forming boards due to insufficient bracing, pouring too fast, or pouring too much.

Bond: To glue together—as in, veneers are bonded to form a sheet of plywood.

Bow: Distortion of a wood structural panel so that it is no longer lies flat lengthwise.

Brace / bracing: A concrete-forming accessory that acts as a temporary support for aligning vertical concrete formwork. One end of the brace attaches to the form and the other anchors to the ground.

BS1088-1 2003: Marine plywood standard.

BS5268 part 2: Load bearing standard for plywood.

Bug hole (blowhole): A small regular or irregular cavity (not exceeding 15mm in diameter) resulting from entrapment of air bubbles in the surface of formed concrete during placement and compaction.

Bundle: A unit or stack of wood panels held together with bands for shipment. (Stack size varies throughout the industry, with the average stack running about 30" to 33" high.) Cathedral Grain: A specific grain pattern found in plain-sliced or flat cut veneer characterized by a series of stacked “V” and inverted “V” shapes.

CE2+: For structural applications, ie walls ceilings, floors etc (included in CPD - EN13986)

CE4: For use in construction for NON structural applications (under above-mentioned CPD)

Center (Centers): Inner ply or plies of a plywood panel where the grain runs parallel with that of the face and back plies.

Checking: When wood exposed to alternating moist and dry conditions eventually develops open cracks or “checks.”

Class I, II: Term used to identify different group combinations of wood species in the plywood substrate of concrete-forming panels.

Core (Cores): In conventional plywood, inner plies where the grain runs perpendicular to that of the outer plies. In composite panels, a layer of reconstituted wood.

Core Gap (Center Gap): An open veneer joint extending through, or partially through, a plywood panel.

Crossbar: A defect in panel manufacturing where a piece of veneer runs perpendicular to the length of the board.

Crossband (Cores): In plywood, the veneer layers with grain direction running perpendicular to that of the face plies.

Cup: Crosswise distortion of a wood structural panel from its flat plane.

Cut: The way a log is cut. For example: rotary cut, rift cut, plain slice, quarter slice, half round slice.

Delamination: Separation between plies or within reconstituted wood due to adhesive bond failure. Separation in an area immediately over or around a permitted defect does not constitute delamination.

E1: lowest amount of formaldehyde emission from sheet material

E2: Higher formaldehyde level from sheet material.

EN 13986: EU Directive for Construction Products (CPD)

EN 636: Classification of the species of plywood under the above directive

EN 636-1: Species for interior conditions

EN 636-2: Species for humid conditions

EN 636-3: Species for exterior conditions

EN 314: Classification of the bonding/glue under EN 13986.

EN 314-1: Glue for in interior conditions

EN 314-2: Glue for humid conditions

EN 314-3: Glue for exterior conditions

Edge Seal: A coating (sealant, paint) applied to the edges of a wood structural panel to reduce its water absorption.

Face: The highest-grade side of any veneer-faced panel that has outer plies of different veneer grades. Also, either side of a panel where grading rules draw no distinction between faces. For example, the face of an A-C panel is the side with the A-grade outer ply. Both sides of an A-A or B-B panel are referred to as faces.

Face Checking: Partial separation of wood fibers parallel to the wood’s grain or a panel’s veneer surface caused chiefly by the strains of weathering and seasoning. Face Grain: Direction of the grain on the outer ply (face) of a veneer-faced panel in relation to its supports. A panel’s greatest stiffness and strength is where it runs parallel to the face grain.

Form: A temporary erected structure or mould for supporting and containing concrete during placement and while it’s setting and gaining enough strength to become self-supporting. Formwork: Temporary structures or forms made of wood, metal, or plastic used when placing concrete to ensure the slurry is shaped to its desired final form.

FSC: Forest Stewardship Council,scheme certifying sustainability and legality of Timber products.

Grade: See Below

Grain: The natural growth pattern in wood. The grain runs lengthwise in the tree and is strongest in that direction. Similarly, grain usually runs the long dimension in the face and back veneers of a plywood panel, making it stronger in that direction.

Half-Round Slicing: When a log is cut tangential to its growth rings, the result is a plain sliced or rotary grain pattern.

Hardwood: Wood of deciduous or broad-leaved trees (oak, maple, ash, walnut) as distinct from the softwood of coniferous or needle-leaved trees (pine, fir, spruce, hemlock).

HDO: See High Density Overlay.

High Density Overlay (HDO): Plywood finished with a resin-impregnated fibre overlay system with a minimum of 54% resin content on the pouring face, that provides a hard extremely smooth or uniform surface, requiring no additional finishing. HDO is highly resistant to chemicals, abrasion, and comes in varying overlay combinations: 100/30; 100/100; 120/30; 120/120. These numbers represent the combined weight of paper and resin in pounds per 1000 sq. ft. (msf). The first number corresponds to the pouring face of the panel; the second number to the panel back. A variety of combinations are offered because resin content on the pouring face directly affects the concrete surface finish, as well as the number of reuses obtained from each panel. Depending on the combination of overlays on the pouring face, one can achieve architectural concrete finish in either a semi-gloss or high-gloss finish, although some evidence of underlying grain shall be permitted.

I-Joist: An engineered wooden joist that is a product designed to eliminate problems that occur with conventional Timber joists. Invented in 1969 and used widely through out the world, the I-joist is an engineered wood product that has great strength in relation to its size and weight, holes for plumbing services and Wiring ect. It can be drilled where required via the Web section of the joist and is an excellent alternative to 9x2 softwood timber joists and lighter than Metal web configurations.

Inner Plies: All plies of a plywood panel except the face and back.

Kerf: A slot made by a saw. Also denotes the width of a saw cut. Knot: Natural growth characteristic of wood caused by a branch base imbedded in the tree trunk.

Knothole: Void produced when a knot drops out of veneer.

Layer: In plywood, a layer consists of one or more adjacent plies having the wood grain in the same direction.

Lay-Up: In manufacturing wood structural panels, the stage when veneers or reconstituted wood layers are “stacked” in preparation for pressing into complete panels.

Marine Plywood: Good-quality, hardwood plywood made with waterproof glue and not treated with chemicals. Higher grades are lightweight, strong, and free of defects. A popular choice for building boats and boat parts.

Medium Density Fiberboard (MDF): A highly versatile wood flour material consisting of highly compressed pressure-cooked wooden fibers combined with a synthetic resin or other bonding systems. A product valued for the quality of its cut edges, it can be used to form a decorative surface ready for painting.

MDO: See Medium Density Overlay. Medium Density Overlay (MDO): Plywood finished with an opaque resin-treated fiber overlay with a minimum of 35% resin content by % of weight of paper and resin in pounds per 1000 sq. ft. (msf). It provides a smooth matte finish, uniformly textured surface, and reasonable reuse. Concrete finish will be of the non-architectural variety because the overlay will transmit moderate grain/patch transference to the concrete surface.

Metal Web Joist (open web joist): It is termed as a light weight timber & steel truss that consists of a triangulated web system and parallel chords, proportioned to span amid bearing points. They are also commmonly know as Space Joist, Posi joist (or Pozi Joists) , Easi joist or Eco Joist. Not to be confused with their generally more cost effective substitute, I-Joist.

O & ES: Oiled and edge-sealed.

Overlaid Plywood: Plywood panels with factory-applied, resin-treated fiber faces on one or both sides.

Oxidation: The result of exposure to the elements which is usually yellowing, browning, or greying discolorations of timber.

P & TS: Plugged and touch-sanded. Usually noted more simply as PTS.

Patch: A wooden insert filling a defect in veneer. Boat patches are oval shaped with sides tapering to points or small rounded ends. Router patches have parallel sides and rounded ends. Sled patches are rectangular with feathered ends.

PEFC: Programme for Endorsement of Forest Certification (scheme certifying sustainability and legality similar to FSC above)

Plug: A circular or dog-bone shaped wood patch or a synthetic filler of fiber and resin used to fill openings and provide a smooth, level, durable surface.

Ply: A single veneer in a panel.

Plyform: Also see B-B Plyform. Plyform is an APA – The Engineered Wood Association designation and includes MDO and HDO.

Release agent: Material used to prevent bonding of concrete to a surface, such as to forms.

Repairs: Any patch, plug or shim in a veneer.

Scarf (Scarf Joint): An angled or bevelled joint in plywood or veneer used to splice pieces together. The length of the scarf is 8 times the thickness.

SE: Square edged, as in the finish at the edge of the Board.

Shim: A long narrow wooden or synthetic repair not more than d/bg" wide.

Softwood: Wood of coniferous or needle-leaved trees (pine, fir, spruce, hemlock) as distinct from the hardwood of deciduous or broad-leaved trees (oak, ash, maple, walnut).

Stickers: Wood strips, also called dunnage, placed under units of plyform to elevate them off the ground. Stickers should be kept in line when stacking units vertically. Using three evenly spaced stickers is recommended.

T + G: Tongue and groove, as in the finish at the edge of the Board.

TRP: Tropical Replacement Plywood.

Veneer: A thin sheet of wood laminated with others under heat and pressure to form plywood. Also called ply.

Veneer Grade: The standard grade designations of softwood veneer used in panel manufacture. The six grades are:

N: Special order “natural finish” veneer. Select all heartwood or all sapwood. Free of open defects. Some repairs permitted.

A: Smooth and paintable. Neatly made repairs permitted. Also used for a natural finish in less demanding applications.

B: Solid surface veneer. Router or sled repairs and tight knots permitted.

C plugged: An improved C veneer, with splits limited to b/i" in width and knotholes and borer holes limited to W" by V".

C: Knotholes up to 1" in diameter. Occasional knotholes V" larger permitted—but only if the total width of all knots and knotholes within a specified section do not exceed certain limits. Limited splits permitted. Minimum veneer grade permitted in exterior plywood.

D: Knots and knotholes up to 3" in width, and up to V" larger under certain specified limits. Limited splits permitted.

Void: See Core gap.