Chapter 3: Wood Flashcards by Amanda Selvage

Protective layer around trunk

Bark

How well did you know this?

Not at all

Perfectly

The center of the trunk, a small zone of weak wood cells, the first year’s growth

Pith

How well did you know this?

Not at all

Perfectly

Source of new cells

Cambium

How well did you know this?

Not at all

Perfectly

Dead cells that contribute to the structural strength

Heartwood

How well did you know this?

Not at all

Perfectly

The direction of the long axes of the cells - changes appearance and physical properties

Grain

How well did you know this?

Not at all

Perfectly

Cells are larger and less dense

Springwood/earlywood

How well did you know this?

Not at all

Perfectly

Concentric bands of _____ and ______ make up the annual growth rings in a trunk that can be counted t determine the age of the tree.

Springwood; summerwood

How well did you know this?

Not at all

Perfectly

Needlelike leaves that remain in cold weather, come from coniferous trees. Mostly in North America, fast growing, plentiful relatively inexpensive.

Softwoods

How well did you know this?

Not at all

Perfectly

Most drop their leaves seasonally, come from broad-leafed trees. Slower growing, more expensive.

Hardwoods

How well did you know this?

Not at all

Perfectly

Main microstructure:

tracheids: large longitudinal cells
rays: radial cells

Softwoods

How well did you know this?

Not at all

Perfectly

More complex microstructure:

fibers: longitudinal, small-diameter cells
vessels/pores: longitudinal, large-diameter

Hardwoods

How well did you know this?

Not at all

Perfectly

Most lumber for building structural frames come from _____. Furniture, cabinetry, interior paneling, flooring, and other fine woodwork are composed of _____ (and some denser _____).

Softwoods; hardwoods; softwoods

How well did you know this?

Not at all

Perfectly

Comes from forests managed according to standards for long-term sustainability, resource conservation, etc. Protects the forest ecosystem and maintains long-term forest economic viability.

Environmentally certified wood

How well did you know this?

Not at all

Perfectly

What are some wood certification programs and organizations?

The Forest Stewardship Council: certification program encompassing ecological, economic, and social purposes.
Forest Management Certification: applied to forests where trees are harvested.
Chain of Custody Certification: applied to the manufacturers and distributors that process the wood after it leaves the forest.
FSC Controlled Wood: certification that assures wood products were not illegally harvested or associated with other highly objectionable practices.
FSC Mixed Sources: label meaning the wood may include Chain of Custody, Controlled Wood, and recycled wood.

How well did you know this?

Not at all

Perfectly

Lengths of squared wood for use in construction

Lumber

How well did you know this?

Not at all

Perfectly

Logs

Roundwood

How well did you know this?

Not at all

Perfectly

A circular saw or bandsaw

Headsaw

How well did you know this?

Not at all

Perfectly

Judges how to obtain the maximum marketable wood from each log, and uses hydraulic machinery to rotate and advance the log in order to achieve the required succession of cuts

Sawyer

How well did you know this?

Not at all

Perfectly

Lumber from softwood, significant portions of the growth rings are oriented roughly flat. Greater distortion during drying, more uneven.

Plainsawn

How well did you know this?

Not at all

Perfectly

Lumber from softwood, the growth rings are consistently aligned at ~45 degrees or steeper. Less distortion during drying.

Quartersawn

How well did you know this?

Not at all

Perfectly

When the cut produces an appearance where the rays appear prominently as contrasting elements.

Flecks/flakes

How well did you know this?

Not at all

Perfectly

Lumber with growth rings that align roughly 30-60 degrees to the boards broader face

Riftsawn

How well did you know this?

Not at all

Perfectly

The weight of the water in the wood as a percentage of the weight of the dry wood.

Moisture content

How well did you know this?

Not at all

Perfectly

Water stored in the cell cavities

Free water

How well did you know this?

Not at all

Perfectly

Water held more tightly within the cellulose of the cell walls

Bound water

Moisture condition, averages around 30%

Fiber saturation point

Final moisture condition

Equilibrium moisture content

The extent of drying

Seasoning

As wood dries below 30% moisture content, it shrinks mostly in _____, and only slightly in _____ (radial).

Cross-section; length

_____ lumber is lighter, stronger, and stiffer than _____ (or ______) lumber.

Seasoned; green, unseasoned

Faster than seasoning, requires more energy

Kiln drying

Moisture shrinkage along the length of the log - negligible

Longitudinal shrinkage

Shrinkage radially, many times larger by comparison

Radial shrinkage

Shrinkage around the circumference

Tangential shrinkage

Smoothed, more dimensionally precise, and safer to handle

Surfaced

High speed automatic machines for surfacing

Planes

Most lumber surfaced on four sides, for framing lumber

Surfaced four sides (S4S)

Often hardwoods are left with two rougher edges to be finished by the finish woodworkers, for finish lumber.

Surfaced two sides (S2S)

After seasoning, removes some drying distortions

Surfacing after seasoning (S-DRY)

Before seasoning, sometimes more economical. Best for wood species that don't distort excessively as they dry.

Surfacing before seasoning (S-GRN)

What are the different types of growth characteristics?

Knots: in structure of tree; branches are joined at the trunk Knotholes: holes left by loose knots dropping out of the wood Decay Insect damage

What are the different types of manufacturing characteristics?

Splits and checks: caused by shrinking stresses Crooking, bowing, twisting, cupping: occur from non-uniform shrinkage Wane: irregular rounding of edges of faces caused by sawing pieces too close to the perimeter of the log

Used to rare strength and stiffness properties of a piece of lumber, done visually or by machine

Structural grading

Inspectors examine, judge, and stamp each piece

Visually grading

An automatic device accesses the structural properties of the wood ad stamps a grade on the piece

Machine grading

Resistance to bending

Machine stress-rated

Rating by collections of individual wood species that are sufficiently similar in their properties that they may be used interchangeably

Species group/species combination

Ranking of visual qualities of lumber intended for flooring, trim, cabinetry, and other finish, nonstructural uses

Appearance grading

How are board feet measured (actual or nominal)?

Nominal

Wood produced in very thick sheets (~1/8-3mm in thickness or less)

Veneer

Produced by inserting a log into a large lathe and spinning the log knife edge

Rotary-cut/rotary-sliced veneer

Produced by pressing a log against a knife, without rotating the log

Sliced veneer

The log from which veneer is taken

Flitch

Arranged in the finished work in the same order in which they came from the log, so that grain patterns on adjacent pieces match as closely as possible

Sequenced

Large wood structural beams produced by joining many smaller strips of wood together with glue

Glue-laminated wood (glulam)

End joints between individual joints

Finger-jointed/scarf-jointed

Where would you find cross-laminated timber?

Walls, floors, roofs

Substitute composite laminated veneer lumber for the usually solid wood top and bottom laminations in the beam

Hybrid glulam beams

I-joists can span further than _____ _____.

Solid lumber

Structural panels laminated from solid lumber, which the orientation of members in each layer alternating from those above and below; the resulting panels are suitable for use as structural wall, floor, or roof components

Cross-laminated timbers (CLTs)

Greater than 50% plastic, durable, maintenance-free, decay-resistant, finish and structural

Plastic lumber

What are the advantages of cross-laminated timber?

- structural components can be produced in shapes and sizes not otherwise available - quality can be carefully controlled - lightweight - structurally efficient - high degree of prefabrication and rapid on-site assembly

Substitutes for solid lumber and are made from wood veneers or wood fiber strands and glue

Structural composite lumber (or engineered lumber)

Made from shredded wood strands, coated with adhesives pressed into a rectangular cross section, and cured under heat and pressure

Laminated strand lumber (LSL) and oriented strand lumber (OSL)

Made from thin wood veneer sheets; are as wide as the member is deep; glued and laminated into thicket members

Laminated veneer lumber (LVL)

Made from long, thin strips of wood veneer glued and pressed in a process similar to that for LSL and OSL, but wit the veneer strips arranged more uniformly parallel than the strands in those other products

Parallel strand lumber (PSL)

Manufactured wood members used for framing of both roofs and floors; I-shaped

I-joists

Made from blends of plastic with wood or agricultural fibers, usually in roughly equal proportions; may be prefinished

Wood-plastic composite (WPC)

What is an example of wood plastic composites?

Exterior decking, wood trim

Lumberlike products made entirely or mostly from plastic resins

Plastic lumber

Lumberlike products manufactured from recycled plastics

Recycled plastic lumber (RPL)

What is the most common material used in the manufacture of plastic lumber?

High-density polyethylene (HDPE): obtained from recycling postconsumer waste (milk jugs, detergent bottles, etc.).

Most commonly made from high-density polyethylene reinforced with glass fibers; can be formulated to be as strong as conventional solid wood, although less stiff and more prone to long-term creep under permanent loads.

Structural-grade plastic lumber (SGPL)

What are the three types of structural wood panels?

1. Oriented strand board 2. Particleboard 3. Fiberboard

What are structural panel types (oriented strand board, particleboard and fiberboard) used for?

Sheathing on framed walls and roofs, and subflooring over floor framing

What are the differences in the three types of structural wood panels?

Oriented strand board: long shreds (strands) of wood compressed and glued into 3-5 layers. They are oriented in the same manner each layer. Strongest and stiffest. Particleboard: different ranges of smaller wood particles than OSB that are compressed and bonded into panels. It is a base material for wood veneer and plastic laminate, or used as an underlayment panel, a smooth base for resilient flooring application. Fiberboard: very fine-grained board made of wood fibers and sentencing resin binders. Mostly interior uses. More dimensionally stable and stiffer, and able to hold fasteners better. Most common type is medium-density fiberboard (MDF) used for cabinets, furniture, moldings, paneling, and many other manufactured products.

Chemical treatments are used to counteract two major weaknesses of wood:

Combustibility and susceptibility to attack by decay and insects

Placing lumber in a vessel and impregnating it under pressure with certain chemical salts that greatly reduce its combustibility; expensive; used in roof sheathing in attached houses and framing for nonstructural partitions, and other interior components.

Fire-retardant treatment

Used where decay or insect resistance is required, like with wood that is used in or near the ground; exposed to moisture; fences, decks, and marine docks; high termite risk areas.

Preservative-treated wood (also called pressure-treated wood)

What are the different types of wood fasteners?

``` Nails Screws Bolts Timber connectors Toothed Plates Sheet Metal and Metal Plate Framing Devices Wood Adhesives ```

What are the differences between nails, and screws and bolts?

Nails: inexpensive, fast and easy to install; may be driven by hand or nail gun; sized in pennies (d) such as 16d=3-1/2"; plain, uncoated steel (bright), galvanized (zinc, corrosion resistant) stainless steel, aluminum and copper Screws and bolts: threaded fasteners; greater holding power than nails; bolts require pre-drilled holes; some screws require pilot holes, while some are self-drilling

Used in factory-produce lightweight roof and floor trusses; driven into wood with hydraulic presses, pneumatic (air) presses, or mechanical rollers; act as splice plates with a very large number of built-in nails.

Toothed plates

Manufactured for joining wood members or strengthening their joints; most common is joist hanger.

Sheet Metal and Metal Plate Framing Devices

Type of timber connector inserted in matching circular grooves to mate pieces of wood clamped together with a central bolt, providing greater capacity by spreading the load across a larger area of wood than can be done with one or a few bolts.

Split-ring connector

What are the different types of prefabricated wood components?

Trusses Prefabricated panels Factory-built housing

What are trusses?

Light wood members (2x4, 2x6) joined with toothed plates; have a long-span capability, and are rapidly erected on site.

What is factory-built housing?

Modular construction: constructed to local building code requirements, but factory-built and trucked to construction site.