Chapter 7 Wood Construction Flashcards
Types of wood used in construction are typically __________ including
Soft woods
Pine
Fir
Spruce
Intrinsic defects of wood include
Knot Knotholes Decay Splits Warping
Solid lumber includes
Dimensional lumber , boards , Timbers
What is dimensional lumber
Lumber with standard nominal measurements fore use of construction
Dimensional lumber is available in what lengths
8 to 24 feet
What is nominal dimension lumber
Actual dimensions of processed lumber do not match the nominal dimensions within defined parameters
What’s the difference between nominal lumber and dimensional
The process of cutting a log into a rough lumber , smoothing it , shrinkage while drying
Dimensions of a piece of lumber will reduce in size to standard size in the finishing process
Solid wood has a useful to stem strength comparable to some types of ______ basis of strength to unit weight
Steel
What in wood greatly reduces its strength
Defects in wood
Tensile strength of wood is considered
About 700 psi
_________ is a significant factor In wood strength, as this leaves wood after the tree is cut the wood begins to shrink in size and increase in strength
Moisture content
Structural lumber has what moisture content
19%
Moisture is expressed in the tens of
Specific gravity
Wood is stronger _______ to the grain than against the grain
Parallel
What’s the allowable compressive strength parallel to the grain is from
325 to 1700 psi
When loaded in the direction of the grain wood strength is comparable to
Steel
Components are produced from a combination of wood particles and a bonding agent
Engineered wood
Engineered wood products provide the advantage of
Strength and cost efficiency
The disadvantage of engineered wood products include
Quick and unpredictable failure under fire conditions
What is grain
Direction of growth of a tree
Construction using only engineering materials is called
Engineered structural system
Material made of wood strips and resin shaped and bonded with heat and pressure
Laminated wood
Wooden structural members composed of many relatively short pieces of lumber glued together and pressure to form a extremely long strong beam
Glue laminated beam
Easy to produce but can not be used where tensile stresses will be transmitted along the length of the beam
Butt joint
Scarf or finger joints can be used to transmit
Tensile stresses
Thickness , depths , lengths of finished beams
Thickness - 3/4 to 2 inches
Depths - 3-75 inches
Lengths - up to 100 ft
Laminated components may have comparable structural integrity to solid wood components under fire conditions when
Protected
Glulam beams are used frequently in
Heaven timber construction where greater lengths are required
Laminated veneer lumber used sheets of veneer peeled from the
Outer portion of the log
LVL is used in I joist and beams sections that are
1 3/4 to 3 1/2 inches thick
Parallel strand lumber produced in standard size ranges of
2 to 8 ft
Laminated strand lumber is made of long strands of wood up to _________ in lengths and are typically used for _______ beams and columns
12 inches
Short span beams and columns
Thermoplastic composite lumber is wood like product made of what, and is not intended to be used in ________ flog a building
Polyvinyl chloride (PVC)
Polyethylene
Not intended to be structure framing
Thermoplastic composite lumber is primarily used in
Outside decks and railing because of the resistance to weather
What is the flame spread of thermal plastic composite lumber
Flame spread is 80 and fire conditions will melt like plastic and burn black smoke , sooty unlike wood
Nonveenered components of panels should not be trusted to maintain _________ if exposed to fire conditions
Structural integrity
Plywood is produced in standard sheets of what size and the direction of the grain is aligned at _______ angles of each other
4ft by 8ft
Right angles
Plywood panels are used mainly for
Structural purposes including sheathing over a wood frame building
_________ panels are made of engineered wood formed into sheets using resin, heat, pressure they are what type of boards
Nonveenered panels
Oriented strand board
Particle board
Waferboard
Uses long strand like wood particles compressed and glued into 3-5 layers, strands are presented in the same direction in each layer
Oriented strand board
Not generally used for structural applications although is may be used in lateral force testifying diaphragms
May be single or multi layer
Particle board
What board is similar to particle board but uses wafer like pieces of wood
Waferboard
SIPs are are as stable as the _________ for structural collapse
The glues that hold them together
Serve several functions including insulation and structural support
Composite panels
One type of composite panel consists of outer wood panels (osb) with a plastic foam core between the panels, the foam between is usually polyurethane
Structural insulated panels (SIPs)
Polyurethane increase fire resistants compared to
Polystyrene
SIPs can be used to increase energy efficiency and the inner core can be up to 1 ft thick for large ____________
R values
What’s is R value
A measure of the ability of a material to insulate, used in structural engineering and construction , with higher R value are more effective
This prevents rapid speed of fire through concealed spaces within combustible construction
Fire stopping or fire blocking
2 inch nominal lumber
Gypsum board
The placement of fire stopping is specified in
Codes
In platform frame building the _______ installed in the top of the studs provides a fire stop that will block the spread of fire between floors within the walls
Plates installed
Ballon frame construction firestoppers must be provided addition to the
Structural members
Building codes require _________ i attic spaces with combustible construction
Draftstopping
The usual requirement for draftsoppers is for the attic space to be subdivided into areas of
3,000 sqft
What is sheathing
Layer of material installed outside of the studs to provide structural stability, insulation, and under layer for siding
A layer of _________ between the sheathing and the siding acting as a vapor barrier
Building wrap
Modern synthetic wrap has more fire resistant than felt or tar paper
Foam insulation is combustible and because flame spreads rapidly over its surface , _______ impose stringent regulations on its use
Building codes - require that the foam insulation include a face of that serves as a thermal barrier such as gypsum board to prevent or slow surface ignition of foam
___________ covered with either paper or foil are commonly used to provide insulation in stud spaces
Fiberglass batts
__________ is the exterior finish or skin
Cladding
___________ insulation are applied as soft foam that hardens after application, treated with flame retardants before application
Solid fill foam
What are the two types of solid fill foam insulation
Urea formaldehyde
Polyurethane
The combustibility of a siding material can affect fire behavior by allowing
Exterior fire travel or ignition due to an exposure fire
Overhaul of this product needs to let environmental officials notified per AHJ
Asbestos (commonly used from 1930s til 1970s )
A wood frame building provided with an exterior brick or stone is called what
Veneer
Veneers must be tied to the wood frame wall at intervals of
16 inches ( veneers add little structural support)
Interior walls of wood framed buildings can be left exposed with not interior finishes such as garages and sheds is classified as what
Type V-B ( wood frame , unprotected)
Wood frame building including the floor and roof construction is provided with protection to achieve a 1 hour fire resistance is classified as
Type V-A (wood frame , protected)
Of a wood frame building is equipped with an automatic sprinkler system codes may permit the elimination of the
1 hour structural fire resistance
A code may permit the elimination of structural fire resistance for roof member located more than ________ above the floor level
More than 20 feet
________ and ________ are commonly used where a specified degree of fire resistance Is required
Gypsum board
Plaster
Prefabricated and shipped to the construction site and common materials used
Manufactured components
Adhesives
Dimensional lumber
Metal fasteners
Panels
Control on variables of wood, lumber can be graded (evaluated) for both
Structural strength and appearance
Wood panel products are graded for their structural use and their
Exposure durability
One serious and fundamental drawback to wood as a building material is it’s
Combustibility
Wood construction has long been known to present a fire hazard because the support system itself
Contributes to the fire load
Ignition of wood occurs when an ________ of sufficient intensity is applied to the wood
Ignition source
The ignition source such as flame must produce enough heat to raise the temperature of the wood to a point where _______ begins
Pyrolysis
What is thermal decomposition of wood and begins at a temperature somewhere below approx 392 Degrees
Pyrolysis
The heat of combustion is measured in
British thermal units BTU
Relationships between the available surface area of the fuel and the mass of the fuel, used to product the rate of fire consumption of combustible material
Surface to mass ratio
What are the 2 methods of fire retardant treatment are
Surface coating
Pressure impregnation
Charring of wood reduces the formation of _________ in the wood and slows flaming combustion
Volatile Gases
Fire retardant treatments reduces
Wood strength allowable stresses must be matched to the values indicated after treatment
The fire resistance of heavy timber column and beams has been tested with the standard
Astm e 119
Wood framing systems most frequently encounter can be broadly classified into two basic types
Light wood framing
Heavy timber framing
The exterior wall studs are continuous from foundation to the roof and vertical combustion spaces between the studs provide a channel for the rapid travel of fire between levels
Ballon frame construction
Shrinkage in lumber occurs to a greater degree in the cross sectional dimensions than in its
Length
Exterior wall vertical studs are not continuous to the second floor and vertical studs are erected and constructed to the floor
Platform framing
Platform framing is more prone to shrinkage than
Ballon framing
