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The Material Wood
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Design
engineered wood
Richard LuxenburgSuivre
Professor of Architecture à Anne Arundel Community CollegePublicité
The Material Wood
- “ Crisscrossing light wood frame recalls Gothic and surrounding trees while lifting the mind skyward.” E. Fay Jones and Associates. Thorncrown Chapel Eureka Springs, Arkansas 1980 WOOD
- Softwoods : Conifer Trees (pine, fir, spruce) for framing and sheathing
- Hardwoods - Deciduous trees (leaf trees) Like maple, oak ash, beech, birch Used for Flooring, moldings, furniture
- Types of Trees / Woods Oak Poplar Pine
- Typical Sawing Method
- Differential Shrinkage (between radial & tangential) during drying can cause distortions
- Spruce, Fir, or Pine Stud Surfaced Dry No 2 Lumber Kiln Dried (19% moisture)
- Structural Composite Lumber (PSL)
- 16d Galvanized 16d Sinker Deformed Shank 10d Galv. Spiral Finish Nail Roofing Nail (far right)
Notes de l'éditeur
- Bark PROTECTIVE LAYER OUTSIDE IS DEAD - INSIDE ALIVE Cambium VERY THIN CREATES NEW CELLS Sapwood STORE NUTRIENTS & TRANSMITS SAP THICK - LIVING Heartwood DEAD WOOD PROVIDES STRUCTURAL STABILITY Pith EARLY YEARS GROWTH SMALL - WEAK
- Primarily Hollow, Cylindrical Cells - “TRACHEIDS” Axis running parallel to the tree Tough Cellulose bond by Lignin IMAGINE A GROUP OF STRAWS Impact on the properties of wood PARALLEL WITH GRAIN (TUBE) STRONG PERPENDICULAR - WEAK
- Springwood (earlywood) Faster growth Cells larger and less dense Summerwood (latewood) Slower growth Cells smaller and denser APPEARS DARKER HENCE - THE RINGS
- Softwoods - Coniferous Trees “ SOFT” OR “HARD” NOT NECESSARILY LITERALLY SIMPLE MICROSTRUCTURE COARSE UNINTERESTING GRAIN PINE, SPRUCE, FIR, CEDAR MOST OF THE LUMBER USED IN BUILDING WHY??? GROWS FASTER, MORE PLENTIFUL, MORE ECONOMICAL Hardwoods - Broad leafed trees MORE COMPLEX STRUCTURE BEAUTIFUL GRAIN PATTERNS PRIMARILY - FINE CABINETRY & DOORS, TRIMS / ACCENTS OAK, POPULAR, WALNUT, MAPLE
- Structural Framing GENERALLY PINE, FIR OR SPRUCE Subfloors and Roof decking GENERALLY WOOD PANELS Siding - Structural & Exposed STRUCTURAL - OFTEN WOOD PANELS EXPOSED - NATURALLY DECAY RESISTANT OR TREATED CEDAR, CYPRESS Finish cabinetry and Trim PAINTED OR LAMINATED - PANELS OR SOFTWOODS “ EXPOSED”/ FINISHED - HARDWOODS
- 1ST CUT (LOG) AND TRANSPORT TO THE MILL Plain Sawing Maximum Yield Varying grain pattern CAUSES DRYING DISTORTIONS DIFFERENT SURFACE APPEARANCE LESS DURABILITY Most common use - Framing lumber WHY??? NOT SEEN STRUCTURAL QUALITIES ACCEPTABLE ECONOMICAL
- WHY DRY WOOD??? WATER IS 30% TO 300% OF DRY WT. Seasoned lumber @ 19% or less HEAVY, WEAKER, LESS STABLE Drying Types Air CUT & STACKED IN OPEN AIR DRIED - CAN TAKE MONTHS Kiln CUT & STACKED KILN DRIED - A MATTER OF DAYS FASTER, HIGHER QUALITY PROCESS Drying Effects Shrinkage LENGTH - NEGLIGIBLE RADIAL - MEASURABLE AMOUNT 12’ BOARD - 30% TO 15% (2% SHRINKAGE - 1/4”) TANGENTIAL - UP TO 50% > RADIAL (STRESSES INDUCED) Reduced weight Increase of strength and stiffness More dimensional stable
- Purpose; Smooth Dimensional precision Designations; S2S, S4S FRAMING - S4S SOME HARDWOODS - S2S Performed primarily after drying WHY??? “ SHRINAGE DURING DRYING
- Growth defects Knots & knot holes LIMBS / BRANCHES Decay and/or insect damage MOIST CONDITIONS, BORES Manufacturing Defects Splits & checks Crook, bow, cup, and/or twist WHAT CAUSES THESE DEFECTS??? DIFFERENTIAL SHRINKAGE
- Strength & Stiffness, or STRUCTURAL OR FRAMING LUMBER VARIES - SPECIES AND IMPERFECTIONS Appearance NON-STRUCTURAL OR FINISH LUMBER Effect on price Grade HIGHER GRADE HIGHER ALLOWABLE STRESSES HIGHER PRICE #1 SELECT - DIFFICULT TO FIND #2 &3 MOST COMMON FOR FRAMING Appearance BETTER APPEARANCE HIGHER PRICE EXAMPLE; 1 x 12 (priced in 2001) # 3 $1 / BF #2 TWICE (2) THE PRICE OF #3 #1 FIVE (5) TIMES PRICE OF #3
- Thickness - “Nominal” < 2 inches - Boards FRAMING LUMBER - MOST 2 to 4 inches - Dimension Lumber = to or > 5 inches - Timbers Widths - “Nominal” Framing Lumber - 2, 4, 6, 8, 10, 12 inches WHY NOT Typically WIDER??? Finish /lumber - 1 inch (typ.)
- Nominal not equal to “Actual” dimensions LUMBER “SAWN” Close to Nominal Then dried and surfaced Up to 6 inches - actual is 1/2 inch less Greater than 6 inches - actual is 3/4 inch less WHY THE “BREAK AT 6”??? MORE DISTORTION & SHRINKAGE TO ACCOMMODATE DURING SURFACING
- Typically; Two (2) foot increments Sizes; 8’, 10’, 12’, 14’, & 16’ WHY NOT Typically LONGER??? Exceptions; 93 inch studs WHY 93 INCHES??? Special order lengths
- FACTORS YOU MUST DECIDE ON WHY DOES SIZE AFFECT COST / BF???
- Lamination Process SELECT LUMBER, GRADE JOINTS - FINGER OR SCARF ADHESIVES BASED ON EXPECTED MOISTURE Why Laminate? Create a size not available naturally Create Shapes ARCHES, CURVES, ETC. Improved Quality PROCESS CONTROLLED DEFECTS REMOVED / CONSIDERED GRAIN DIRECTION CONTROLLED USES CHURCHES LARGE RESIDENTIAL LODGES, RESTAURANTS
- Why Panelize? More “controlled” product (strength, shrinkage, etc.) Efficient use of forest products Increase labor productivity Types Plywood Composite panels Veneered panels
- Thin layers of veneer glued together VENEERS - ROTARY CUT Odd number of veneers Alternating direction of veneers Face veneers parallel USES SAME AS OSB EXPOSED/PAINTED SURFACES FORMWORK COST MORE THAN OSB
- Based on the smoothness & integrity of the veneers Classifications; A, B, C (plugged), C, D B and better sanded smooth Price Variances (2001) 23/32 Exterior A/C = $31 per panel 23/32 Exterior B/C = $20 per panel MOST FORMWORK B/C FINISH AREAS MAY REQUIRE “A”
- INTRODUCED IN THE EARLY 80’s GETTING WIDESPREAD USE Long strand like wood particles Alternate grain orientation (3-5 layers) Compressed / glued Strongest of the Non-veneered WHY IS IT THE STRONGEST??? ORIENTATION OF STANDS Generally more economical than Plywood Uses; Sheathing for floor, roofs, & siding WHY IS IT GETTING WIDESPREAD USE??? STRUCTURALLY SOUND ECONOMICAL - SUBBSTITUTE FOR PLYWOOD NEW GROWTH TREES
- Established by American Plywood Association (APA) Standards based on; Structural adequacy Dimensional Stability UNDER VARYING MOISTURE CONDITIONS Durability of Adhesive
- Panel Grade Span Rating IN INCHES PERPENDICULAR TO SUPPORT LARGER # - ROOF SPAN SMALLER # - FLOOR SPAN
- Thickness Exposure Durability Exterior - siding or continuous exposure Exposure I; Waterproof glue - but veneers are not as high of quality as exterior grade (subfloors, sheathing) - most common rating Exposure II; Minimum wetting
- Combustibility FIRE RETARTANT IMPREGNATED UNDER PRESSURE Decay & Insect PRESSURE IMPREGNATED UP TO 30 YEAR LIFE TYPES CREOSOTE PENTACHOROPHENOL - OILY, CAN’T PAINT WATERBORNE SALTS - GREENISH - CAN PAINT Chromated Copper Arsenate (CCA) being phased out HIGH MOISTURE USES – WHY NOT USE DECAY RESISTANT WOODS??? (CEDAR, REDWOOD, CYPRESS) COST & STRENGTH
- Common flat heads, used mostly for structural connections Finish Nails virtually headless, finish woodwork Common - Used for Framing, Large Shank & Head Box - Smaller Shank, less chance for splitting wood, Used Shingles, Rough Casings Casing, Finish, Brad - Finish Components, Sink Head Deformed Shank - Very Hard to Remove, DW & Flr. Concrete - Masonry & Concrete Cut - Finish Flooring - SQ Head Reduces Cracking Roofing - One of Many, Some Have lead/Rubber Washers
- Size - Measured in “pennies” (Price of 100 nails long ago) Corresponding Lengths Same for Common & Finish Most Common Light Frame Nails - 16d for 2”, 10D AND 8D Coatings Bright/ Plain uncoated steel MOST COMMON USED - NON CORROSIVE OR CONCEALED CONDITION Corrosion-resistant “ EXPOSED TO WEATHER RUST OR STAIN LUMBER GALVANIZED, ALUM., SS Resin/Vinyl Decrease Drive & Increase Holding This nail has a smaller shaft – commonly called a ‘sinker’
- Anchorage Face - Perpendicular to Grain End - Parallel Toe - Angle to Grain Which Has the Most Holding Power??? Which is most common???
- APPLICATIONS FRAMING SHEATHING ROOFING
- “ Head” type PHILLIPS SLOTTED SQUARE HEAD PAN, FLAT, ROUND, ETC. Sizing - Gauge & Length WIRE GAUGE (SAMPLES #8 & #10) LENGTH IN INCHES (AND FACTIONS) Installation HAND SCREW DRIVER “ SCREW GUN”, OR DRILL HOLDING POWER TIGHTER, STRONGER THAN NAILS CAN BE “BACKED” OUT, & REINSERTED Uses CABINETWORK SOME FRAMING APPLICATIONS DECKING - BETTER HOLD - LESS SQUECK
- Lag Screws Large screws Very LARGE Screws, Wrench, ¼ “@ 2-6 in., ½ to 10” FOR HEAVIER STRUCTURAL CONNECTIONS Square or octagonal head Installed w/ wrench Drywall screws Used to attach drywall Drywall Screws (Size, 1 ¼, 1 5/8, 2 “, Screw Gun - Fast, Wood or Metal,
- Heavier structural connections COMMONLY USED W/ TIMBER CONSTRUCTION Sizes 1/4 inch to 1 inch+ LENGTH; ABOUT ANY (PRACTICALLY 10-12”) Types Machine SQUARE OR OCTAGONAL HEAD USED WITH WASHER Carriage ROUND BUTTON HEAD SQUARE SHANK INHIBITS TURNING Washers DISTRIBUTE THE COMPRESSIVE FORCE
- NUMEROUS TYPES AND SHAPES MOST COMMON - JOIST HANGER LIGHT WOOD FRAMING - ATTACHED WITH SCREWS OR NAILS HEAVY TIMBER - ATTACHED WITH BOLTS / LAGS
- ON SITE LESS USES BECAUSE OF NEED TO CLAMP USES FLOOR SHEATHING BASE (SOLE) PLATES WALL PANELS PANELING (WHERE THERE IS A NEED FOR CONCEALED FASTENERS) INCREASE STIFFNESS, ELIMINATE “SQUEAK”
- Uses FLOORS & ROOFS Sizes Typically, 9-1/2” TO 24 “ DEEP LENGTH UP TO 40 FEET+ Composition & cost TOP & BOTTOM - LUMBER OR Laminated WEB - OSB, PLYWOOD COST - COMPARABLE TO 2x
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