WOOD Flashcards
Wood
A commonly used construction material due to its reasonable cost—ease of working—and durability.
Types of wood
Hardwood from deciduous trees (angiosperms)—and softwood from coniferous trees (gymnosperms).
Reasons for using wood in construction
It is affordable—easy to work with—visually appealing—and durable when properly maintained.
Hardwood examples
Oak—mahogany—teak—maple—walnut—and cherry.
Softwood examples
Pine—cedar—spruce—fir—and redwood.
Uses of hardwood
Commonly used for furniture—flooring—tool handles—and high-strength applications.
Uses of softwood
Used for framing—plywood—doors—and general construction.
Mechanical properties of wood
Strength—hardness—stiffness—toughness—warping—nail-holding resistance—and workability.
Strength of wood
The ability to resist breaking when used in beams and columns—influenced by species—moisture—and density.
Factors affecting wood strength
Moisture content (MC)—knots—checks—splits—and irregular grain patterns.
Effects of high moisture content
Weakens wood and makes it prone to warping and decay.
Knots in wood
Circular—hard portions caused by branches that may weaken the structure and affect workability.
Checks and splits in wood
Cracks in wood that develop due to drying stress—reducing its strength.
Irregular grain patterns
Occur when wood fibers grow in different directions—making it harder to cut and shape.
Hardness of wood
Resistance to denting and wear—important for flooring—tool handles—and surfaces requiring durability.
Hardness testing method
Janka Hardness Test developed by Gabriel Janka—using a steel ball to measure resistance.
Janka test process
Measures the force needed to embed an 11.28mm steel ball halfway into a wood sample.
Common uses of hardwoods
Used in flooring—furniture—tool handles—and areas with high wear resistance.
Softwood hardness
Generally softer than hardwoods—making them easier to cut—shape—and finish.
Stiff woods
Resist bending or deflection under load—but may break suddenly if overloaded.
Tough woods
Can absorb shock and resist sudden forces without breaking easily.
Examples of tough woods
Hickory—ash—and oak—which resist impacts and sudden loads.
Warping
The twisting—bending—or bowing of wood due to uneven moisture content changes.
Causes of warping
Uneven drying—improper storage—and variations in temperature and humidity.
Ways to prevent warping
Store wood properly—seal it—and control moisture exposure.
Nail-holding resistance
The ability of wood to hold nails securely—pre-boring holes reduces splitting.
Best woods for nail-holding
Oak—pine—and fir—which provide a strong grip for fasteners.
Workability of wood
How easily wood can be cut—shaped—and finished—softwoods are easier to work with than hardwoods.
Best woods for workability
Pine—cedar—and poplar—which are easier to cut and shape.
Difficult woods to work with
Teak—mahogany—and ebony—which are dense and require specialized tools.
Natural decay resistance
The ability of wood to resist fungi—bacteria—and insects—affecting its durability.
Decay-resistant woods
Cedar—redwood—and teak—which naturally repel moisture and pests.
Ways to increase wood durability
Chemical treatments—painting—sealing—and proper ventilation.
Paint-holding capacity
The ability of wood to retain paint without peeling—cracking—or flaking over time.
Best woods for painting
Pine—fir—and poplar—which absorb paint evenly.
Worst woods for painting
Oily woods like teak and mahogany—which resist paint adhesion.
Physical properties of wood
Color—luster/grain—texture—and density.
Wood color
Ranges from light (softwoods) to dark (hardwoods)—affected by age—sunlight—and stains.
Luster/grain
Describes wood’s surface reflectivity and the natural pattern formed by its fibers.
Texture of wood
Can be smooth—rough—or figured—depending on grain pattern and density.
Wood density
The mass per unit volume—denser woods are heavier—harder—and more durable.
Density classifications
Very light (<0.36 g/cm³)—light (0.36 g/cm³)—moderately heavy (0.36–0.5 g/cm³)—heavy (>0.5 g/cm³).
Effects of high-density wood
Harder to cut and shape—but stronger and more durable.
Effects of low-density wood
Easier to work with—but less durable and more prone to dents.
Construction material selection
Depends on cost—durability—availability—labor—transportation—and compatibility with other materials.
Economic considerations in material selection
Balancing initial investment—maintenance costs—and long-term durability.
Transportation cost factor
Heavy materials like oak and mahogany increase shipping expenses.
Cultural acceptability in wood selection
Some regions prefer locally available or traditional woods for cultural—or environmental reasons.
