Chapter 6 Wood work Flashcards
Bark
Outermost protective layer (A: dead, B: living)
Cambium Layer
Source of new wood cells
Sapwood
Living cells that store and transport nutrients
Heartwood
Dead cells that contribute to structural strength
Pith
Innermost, first year’s growth
Annual Growth Rings
Result from differences in rate of tree growth and density of cells, from spring to summer
Soft Woods
- From cone-bearing (coniferous) trees
- Generally, plain figure (pattern of grain and surface features)
- Mostly originating from North American forests
- Fast-growing, plentiful, relatively inexpensive
- Generally soft, easily worked
- Not all softwoods are soft Douglas Fir is harder some hardwoods
Softwood uses
- structural wood products
- finish trim, shingles and siding
- flooring
Hardwoods
- From broadleafed (deciduous) trees
- Often more interesting figure
- Harvested from around the world
- Slower growing, generally more expensive than softwoods
Hardwoods Softer
Denser, with greater variety of colors and figure
fine trim, paneling
flooring
fine cabinet work, furniture
Certified Wood
- Sustainable forestry management
- Protect forest ecosystem
- Maintain long term forest economic viability
- Some programs also address social responsibilities, for example, the land rights of indigenous peoples.
Forest Stewardship Council (FSC)
Only certifying organization currently recognized for LEED certification
Plain Sawn Cut
growth rings roughly parallel to wider face of board
Quarter Sawn Cut
growth rings close to perpendicular to wider face of board
Rift Sawing Cut
cuts made radially to center of tree
Plain Sawn Lumber
- Broader grain pattern on wide face
- Greater distortion during drying
- More uneven surface erosion or wear
- More efficiently sawn from log; less costly
- Also called flatsawn, flat grain
Quarter Sawn Lumber
- More narrowly spaced grain pattern on wide face
- Less distortion during drying
- More even surface erosion or wear
- More costly to saw from log
Rift Sawn
- Riftsawn (left): angle of grain falls between perfectly quarter sawn and plainsawn
- Also called edge sawn, edge grain, vertical grain
Seasoning
- After lumber is sawn, it is seasoned (dried), either in air or in kilns.
- Seasoned lumber is lighter, stronger, and stiffer than green (unseasoned) lumber.
- Decay causing fungi cannot survive in wood with a moisture content (MC) below 20%.
Equilibrium Moisture Content
Wood eventually dries to equilibrium with the surrounding air, reaching its equilibrium moisture content (EMC).
EMC for exterior uses: 15% - 19%
EMC for interior uses: 5% - 11%
Surfacing
Lumber is surfaced to make it smooth and more dimensionally precise.
- Framing lumber: usually surfaced four sides (S4S)
- Finish lumber: may be S4S, or surfaced two sides (S2S), the other sides to be sawn and surfaced by the woodworker
- Surfacing after seasoning (S-DRY): removes some drying distortions
- Surfacing before seasoning (S-GRN): sometimes more economical; best for wood species that don’t distort excessively as they dry
- Construction planking: unsurfaced, resulting in a plank that is stronger (no material has been removed) and more slip-resistant
Structural Properties of Wood
- Wood has both useful tensile and compressive strength.
- Strength varies significantly with direction of grain, species, and presence of knots or other defects.
- Defect-free wood is close to the strength of steel on a per-weight basis, but typical grades are weaker.
- Strength also varies with duration of load, moisture content, chemical treatments, temperature, size and shape of piece.
Lumber Dimensions
-Actual sizes are less than nominal size. E.g.:
-1x4 actual size is approximately ¾” x 3½”
-2x4 is 1½” x 3½”
In U.S., lumber is priced by the board foot, based on nominal, not actual dimensions:
-12 sq. in. nominal cross-section, 1 foot long = 1 board foot
Standard Wood Sizing
- As woodwork lumber is made in standard thickness, reducing waste by using standard sizing is good practice.
- Lumber for millwork is measured in ‘quarters’, which refers to ¼” increments.
- Example: 5/4 lumber is nominally 1-1/4” thick
Plywood
Panel product made from an odd number of layers of thin veneer glued together under heat and pressure
- Each layer is laid perpendicular to the previous one, providing much greater strength than a solid wood piece of similar dimension - Commonly used in finish carpentry, sometimes in millwork construction - Graded based on quality of face veneer - Grades N, A, & B used in interior construction, only N is suitable for natural finishes; A is used for painted finishes, and B is used for utility work, etc. - Composite and laminated wood products are much more dimensionally stable than solid wood
Molding
- Trim used for decorative or functional purposes
- Hundreds of profiles available, Fig. 6.1 shows some common shapes
Gluing for Width
- Gluing for width requires either a ‘tongue and groove’ (shown) or a ‘spline joint
- ‘reveal’ detail is incorporated into design. This is common practice, as it reduces splitting of the corner fibers of the pieces, and allows for minor alignment imperfections
Veneer
- Thin slice of wood, glued to backing material; particleboard, MDF, and plywood used to hold it flat, provide solid substrate
Flitch
individual veneers that come from the same piece of a log.
Methods of Cutting Veneer
- Rotatry Slicing
- Plain Slicing
- Quarter Slicing
- Half-Round Slicing
- Rift Cut
Rotary Slicing
log is spun on lathe, very pronounced grain, least waste
Plain Slicing
growth rings roughly parallel to wider face of board
Quarter Slicing
growth rings close to perpendicular to wider face of board
Half- Round Slicing
: similar to rotary slicing, log is cut in half; characteristics similar to rotary, plain-sliced veneers
Rift Cut
: log is quartered, then sliced at slight angle to growth rings; accentuates growth rings, vertical grain
Cabinetwork
Includes custom-manufactured built-in base and upper cabinets, freestanding fixtures, custom shelving
Many types of joints used for millwork construction to increase strength, improve appearance
In most cases, it is possible to eliminate mechanical fasteners (nails, screws) with good joinery design
Countertop Construction
- Each layer is laid perpendicular to the previous one, providing much greater strength than a solid wood piece of similar dimension
- Commonly used in finish carpentry, sometimes in millwork construction
- Graded based on quality of face veneer
- Grades N, A, & B used in interior construction, only N is suitable for natural finishes; A is used for painted finishes, and B is used for utility work, etc.
- Composite and laminated wood products are much more dimensionally stable than solid wood
Drawer and Door Front Construction
Hundreds of profiles available, Fig. 6.1 shows some common shapes
Flush Construction
drawer/door face installed flush with face frame; requires extra care in construction, should be installed with adjustable hinges, drawer glides
Flush Overlay Construction
fronts of doors/drawers overlap face frame of cabinet; only doors and drawers are visible, all are flush with each other. Should be installed with adjustable hinges, drawer glides
Reveal Overlay Construction
door/drawer fronts separated to reveal face frame behind; reveal varies per design preference. Less expensive, typical of ‘off the shelf’ residential cabinets
Upper Cabinet Construction
- Not as deep as base cabinets
- Underside must be considered as it is visible
- Residential construction with wood construction allows screws through cabinet back into studs; metal stud systems common to commercial construction require blocking between studs, before framing is covered with gypsum board
- Top of cabinet may be detailed against ceiling, dropped soffit, or space may be left above cabinet
- Doors may extend below bottom, to allow finger pull, or to conceal reinforcing member/light fixture concealment trim below cabinet
Shelving
- May be mounted on adjustable metal standards, attached to floor mounted cases, or built into wall-hung cases; can also be fitted with doors
- Many options for edge treatment possible
- Fixed shelving attached with stop dadoes or concealed, interlocking fastening devices in Premium and Custom grade shelving
- Economy grade shelving uses through dadoes for fixed shelves
Panel Types
- Flush Panels
- Stile and Rail Construction
How are panels generally attached ?
- Wood cleats or Z-clips
- Occasionally, screwed to wall, if trim elements cover fasteners, or if exposed fastener system designed as integral to composition
- At ceilings, sufficient space for installation over cleat or Z-clip is necessary; usually 3/4” depending on clip size – can be filled or covered with trim if desired
Panel Construction
- Flush Panels: smooth surfaces with little trim
- Edges between panels can be treated as flush joints, which are joined with splines, or with reveals between panels
- Tight joints should have V-joints or reveals cut into panels to make cracks, movement less noticeable; in humid environments, joint should have gap to allow for expansion/contraction
Stile and Rail Construction
- Consists of a frame of solid wood that contains individual panels
- Traditionally, each panel was made from solid wood; now, most panels veneered
- Attachment to wall similar to flush panels; sometimes screwed to wall, with molding covering screws, with panels doweled or splined together.
Stiles
Vertical frame pieces
Rails
horizontal pieces
Sticking
Panels are held in place with grooves cut into frame sides, or with individual molding pieces
Book Matching
most common; as veneers sliced off log, every other piece is turned over, so adjacent leaves form symmetrical pattern
Slip Matching
consecutive pieces placed side by side with same face sides being exposed
Random Matching
veneers placed in random sequence, veneers from different flitches may be used
Runnning Match
alternates pieces regardless of width
Warehouse matching
- least expensive
- assembled from a single flith that yields 6 to 12 panels
- field cut to fit around the doors, windows . and other obstructions, resulting in some loss gain continuity
- doors and cabinets cannot e matched with paneling
Sequence match
- uniform width manufactured for a specfic job and job with the veneers arranged in sequence
- trimmed to fit around doors and other obstructions, there is moderate loss of gain continuity
- doors and cabinets cannot be matched with the paneling
blueprint matching
- most expensive
- fit the room precisely and to line up with every obstruction so the grain continuiy is uninterrupted
- veneers from the same flitch are matched over door doors, cabinets and others veneer-covered items
High- Pressure Decorative Laminates (HPDL)
- often called ‘plastic laminate’
- Commonly uses MDF substrate; flatter, more expensive than particleboard. MDF is dimensionally stable. Specify formaldehyde-free MDF whenever possible.
Laminate Type
General purpose (GP50) General purpose for vertical surfaces (GP28) Postforming (PF30, PF 42) Cabinet liner (CL20) Backing Sheet (BK20)
Specialty Laminates
Specialty laminates Colorthrough laminates Fire-Rated laminates Static dissipative laminates And many others
Special Woodwork Items
- Doors
- Upholestered Wall Systems
- Solid Surface Materials
Doors
Custom doors, exotic veneers, blueprint matching, specially designed doors commonly constructed by millworkers
Upholestered Wall Systems
Acoustic fabric-wrapped panels often fabricated, installed by woodwork contractor
Solid Surface Materials
- Homogeneous, polymer-based surface material; made of filler & clear resin binder
- Commonly used for kitchen sinks, countertops, places where plastic laminate used
- Expensive, but quite durable, easy for millworkers to fabricate with same tools as woodwork
Finishes
- Opaque Finishes
- Transparent Finishes
Opaque Finishes
- Laquer
- Varnish
- Polyurethane
- Polyester
Lacquer
- high nitrocellulose content, modified with resins
- easy application, low cost
Varnish
resinous material dissolved in volatile liquid
- easy application, low cost
Polyurethane
synthetic finish, very hard, but difficult to repair
- most durable finishes; most expensive; dull to full gloss available in polyurethane
Polyester
synthetic finish, hardest, most durable finish, difficult to repair
-most durable finishes; most expensive
; polyester is full gloss only
Transparent finish
- Lacquer and varnish
- Vinyl
- Oils
- Polyurethane and Polyester
- Stains
Oils
- traditional method, easy to apply, darken with age, require periodic re-oiling
Vinyl
- more chemical resistance than lacquer & varnish; scratch/abrasion resistant
Stains
- applied prior to final finish to change color, appearance of wood; water & solvent based stains available
Millwork
Finished carpentry components, such as moldings, doors, cabinets, stairs, etc. manufactured off-site
