3. WOOD
• Poor heat-conducting properties does not
remove heat from the hand warm to the touch
• Cold: metals, plastics, stone, concrete
• Excellent material for doors, door & window frames,
flooring, trim
5. GROWTH OF TREES
• Wood consists of long,
narrow, hollow cells called
fibers
• Cambium: thin growing
layer
• Sapwood: fibers are active
in the life processes of the
tree but do not grow
• Heartwood: center, consists
of dead fibers, shade darker
because of resins, gums,
minerals
• Pith: thin veil of soft tissue in
the center, no strength
• Bark
6. GROWTH OF TREES
• Fibers
• Cellulose (70% of the
volume)
• paper
• Lignin (the glue, 25%
of the volume)
• Age of the tree
• Determined by
number of rings
7. GROWTH OF TREES
• A pack of drinking
straws held
together w/ rubber
bands
approximates the
fibrous structure of
wood
• Checks: shrinkage
in wood when
water inside it
evaporates
8. GROWTH OF TREES
• Grain: stripes when
wood is sawed
parallel to the
length of the tree
14. LUMBER PRODUCTION
• Lumber finishing
• Rough lumber
• Sawed on all 4 sides
• Dressed lumber/surfaced lumber
• Planed or surfaced on at least one face
• S1S surfaced on 1 side
• S1E surfaced on 1 edge
• S2S, S2E, S1S2E, S2S1E, S4S
• Worked lumber
• Dressed and also worked to provide tongue-and-groove or shiplap
joints
• Seasoning
• Process of reducing the moisture until a suitable moisture level
is reached
16. LUMBER PRODUCTION
• Foot board measure (fbm)
• 1 board foot = 1 sq ft x 1 in. thick
• Ex.
• Calculate the number of board feet in 36 2x4s which are 8 ft
long
• Board feet = (number of pcs x thickness in inches x width in
inches x length in feet) / 12
• Board feet = (36 x 2 x 4 x 8)/12 = 192 bf
17. SEASONING
• Green wood
• Moisture content
• Ways to season
• Air: 4 years for hardwoods
• Kiln
• Subjected to warm, moist air or steams
19. STRENGTH
• Important stresses & corresponding strengths of wood
are divided into 6 types:
• Modulus of elasticity (E)
• Measure of stiffness or resistance to deflection
• Extreme fiber stress in bending (Fb)
• The stress (compression at the top, tension at the bottom) that must
be resisted in a beam undergoing bending
• Tension parallel to grain (Ft)
• Stress induced by pulling apart in a longitudinal direction
• Compression parallel to grain (Fc)
• Stress induced by pressing together longitudinally
• Compression perpendicular to grain
• Stress induced by pressing together in a transverse direction
• Horizontal shear (Fv)
• Stress induced by the tendency for upper fibers to slide over lower
fibers as a beam bends
20. LUMBER CLASSIFICATION
• Grading
• Lumber
• Term including all finished or semifinished wood shaped with
parallel longitudinal surfaces
• Boards
• Pieces 1 ½ in. or less in thickness and 2 in. or more in width
• Dimension lumber
• Pieces at least 2 in. thick and less than 5 in. thick and 2 in. or more
wide
• Timbers
• Pieces 5 in. or more in thickness and width
21. LUMBER CLASSIFICATION
• Factory and shop lumber
• Pieces to be used in making sash, doors, jambs, sills and
other millwork items
• Yard lumber
• Used structurally and includes most of that used in
construction
• Divided according to size and shape into boards,dimension
lumber and timbers
• Boards: roofs, floors, siding, paneling and trim
• Dimension lumber: joists, studs, rafters
• Timbers: infrequently used as part of a structure
• Shoring earthwork or mine tunnels, bracing for concrete forms
23. LUMBER CLASSIFICATION
• Stress-graded
• Each piece is assigned
to a grade depending
on its strength
• Characteristics
• Natural marks resulting
in tree’s growth or from
seasoning, and
manufacturing
inspections resulting
from sawing, planing,
or other manufacturing
operations
24. LUMBER CLASSIFICATION
• Stress-graded
• Each piece is assigned
to a grade depending
on its strength
• Characteristics
• Natural marks resulting
in tree’s growth or from
seasoning, and
manufacturing
inspections resulting
from sawing, planing,
or other manufacturing
operations
26. DETERIORATION OF WOOD
• 4 major enemies of wood:
• Insect, marine borers, fungi, fire
• Insects
• Termites
• Provide physical barrier or a chemical barrier to keep them from reaching the
wood
• Physical barrier: concrete or steel supports that provide a space between the
ground and the wood
• Chemical barrier: saturating the soil adjacent to the structure with poison
• Marine borers
• Mollusks & crustaceans
• Docks
• Creosote oil or creosote-coal tar solution
• Encasement of the wood within concrete
• Fungi
• Rotten wood
• Chemicals
27. PRESERVATION OF WOOD
• Treating with poison so that fungi and insects do not
consume it
• Typical treated wood products:
• Dimension lumber, heavy timbers, round stock, plywood,
specialty items
• Finishes
• Paint
• Enamel
• Varnish
• Sealer
• Semi-transparent stain
• Opaque stain
• Polyurethane varnish
