H2 Wood Framing Flashcards
True or false wood is the second most commonly used building material
True
How long does it take to grow a mature tree for suitable use as lumber
40 to 100 years
Which products have been made from the waste of lumber production or utilize smaller diameter logs?
Particle board, wafer board, dense fiberboard, laminated veneer lumber, glue laminated beams, parallel strand lumber beams, oriented strand board and plywood.
True or false, Wood ladders are used because they are poor conductors of electricity?
True
True or False, both oil and latex paint can be used on wood for interior or exterior purposes?
True
What is the relationship between wood and moisture?
All the properties of wood are affected by its MC, it can change in thickness and width due to it’s MC
How can you protect wood from decay?
Protected with chemicals or by keeping it dry and well ventilated. Below-grade wood must be treated with chemicals.
Eg paints, stains, alkaline copper quaternary and copper azole
How can wooden structures be made fire-resistant?
Using other materials over wood such as plaster or gypsumboard panels.
What are two main reasons for wood cracking?
Drying and nailing are two of many reasons wood may crack or split.
What can cause weakness in a board?
Loose knots
What kind of tree produces hardwood?
Deciduous
What kind of tree produces softwood?
Coniferous.
What is a crown?
It’s in this part of the tree that the food required for growth is manufactured. The crown may consist of the top 15% of the tree.
The more crown a tree has, the more it grows
What are roots?
The roots of the tree perform two functions, anchoring the tree in the soil and absorbing moisture and nutrients.
What is the Trunk of the tree?
The “stem” Provide structural support for the crown and transport food and moisture from the roots to the crown
Wood used for framing should have what MC?
15 percent to 19 percent
Wood used for finishing should have what MC?
8 to 11%
Where is water found within the wood?
Within the cell cavity(Free water) and in the fibres of the cell walls.(bound water)
When wood dries, when does shrinkage occur?
It does not take place until all the free water is gone from the cell cavities.
What is the density of wood?
Wood: 500 to 600 kg/M
What is the density of steel?
Steel: 8000 kg/M
What is the density of concrete?
Concrete 2400 kg/M
Why does using wood for window frames reduce condensation on the inside surfaces?
Wood is a better insulator than metal. Therefore wood is warmer, reducing the chance of warm moist air condensing on the frame.
How can wood be re-used? How do you prepare wood for reuse?
If wooden construction members are removed carefully.
Finish materials: Pull nails through the backside of materials to reduce damage to face materials.
How long does it take for wood to mature to a size that it can be harvested for lumber?
40 to 100 years
What happens when wood is exposed to atmospheric change?
Swelling or shrinkage occurs
Which hold its strength longer in fire situations, wood or steel?
Wood.
Which type of sawing produces the most “flat grain” lumber?
Plain Sawn
which type of sawing produces the most “edge grain” lumber?
Quarter sawn
What angle must the grain be to be considered edge grain?
Greater than 45 degrees
Describe “plain sawing”
Boards are cut through the full width of the log.
Which abbreviation is used for 1 x 10 re-sawn boards?
S1S2E
What does “S-GRN” stand for?
Surfaced green
Name the three main parts of a tree.
Roots»_space;> Trunk»_space;> Crown
This structure is an extremely thin region of living cells, which is responsible for the formation of the millions of new cells produced by a tree each year. The cells produced by this structure form other structures, which make up the bulk of the tree.
Cambium Layer
This region of the tree consists of light coloured, commercially valuable wood. Its function is to conduct sap upward from the roots to the crown of the tree.
Sapwood.
Consisting of dark-coloured, structurally weak material, this structure is located at the centre of the tree. First wood growth takes place around it.
Pith.
These long, narrow structures appear as fine lines on the surface of a cross section of a tree trunk or branch. Their purpose is to conduct food and moisture laterally across the trunk or branches.
Medullary Rays.
This corky material is composed entirely of dead cells. Its function is to protect the tree from pests, disease and damage.
Outer bark.
This part of the tree wood is darker than other structures. Composed of dead cells with natural tannins and resins, it’s more durable and less susceptible to decay than other wood structures. Its main function is to give the tree structural support.
Heartwood.
This region of the tree transports sugars from the leaves down to mix with water and nutrients from the roots.
Inner Bark.
These structures consist of concentric cirlces or rings, which are visible on a cross sectional cut of a new trunk or branch. They can be used to determine the age of a tree and eventually they form the wood grain pattern when a log is sawn into boards.
Annual growth rings.
True or False, Tropical woods tend to have an obscure grain, while most woods native to North America tend to have an obvious grain?
True
What is water in a cell wall called?
Bound water
At what stage of drying does wood begin to shrink?
Once all of the free water is gone from the cell cavity and bound water starts to leave cell walls
Where does the greatest shrinkage take place in a piece of wood?
Width and thickness
A cup is formed when what kind of grain board dries out?
Flat grain dries out, a cup is formed
Which is the heaviest speices of softwood?
Western larch.
Which is the lightest species of softwood?
Western Red Cedar
Which of the three species are considered to be the strongest of the softwoods?
Douglas Fir, Larch, Hemlock.
Which species of wood is considered to be free from resins?
Western Hemlock
Which species of wood is best suited for manufacturing ladders?
Sitka spruce
Name four species of wood that have very little or no taste or odour?
Spruce, some species of pine, balsam fir and alpine fir.
What species of wood is considered to be free from resins?
Western hemlock
Which species of wood is best suited for manufacturing ladders?
Sitka Spruce
Name four species of wood that have very little or no taste or odour?
Spruce, some species of pine, balsam fir and alpine fir
Which species of wood has a deep, warm brown colour?
Western red cedar
Before harvest logs are milled, what happens to them?
They are washed with high-pressure jets and then de-barked.
Which grain of wood will shrink more along it’s width, Edge Grain or Flat Grain?
Edge grain will resist wear better.
How can you tell visually that a board is Edge grain?
The grain pattern on the face of the board appears as relatively straight lines that are paralell to the edge of the board.
The angle formed by the annular growth rings and the face of the board is less than 45 degrees for which board?
Flat grain
Which produces more flat grain boards, Plain or Quarter Sawn?
Plain Sawn
Which produces more edge grain boards? Quarter or Plain sawn lumber?
Quarter
What % of Moisture does BC code allow for Framing Lumber?
19% max
Either Kiln dries or air dried.
What is the difference between surfaced green(s-grn) and surfaced-dry(s-dry) lumber?
S-dry lumber is surfaced AFTER being dried, less shrinkage.
S-grn lumber is surfaced BEFORE being dried, more shrinkage.
Which sides of rough lumber are surfaced?
They are machined on all 4 sides at once with a planer.
What does “S4S” mean?
Surfaced 4 sides (in the milling process)
What is a resawn board?
Example:
Plank is cut in half across their width with a bandsaw. This changes a S4S plank to two S1S2 boards.
How is lumber treated at the mill?
Due to tight packaging and moisture present, lumber is often surface treated at the mil to give cosmetic protection from mold and sap stains.
What is pressure-treated lumber?
Lumber treated with Alkaline Coper Quaternary(ACQ), to protect against fungi that cause rot and against wood-eating insects such as termites.
An S-GRN board of 2-4” has an actual dimension how much smaller?
7/16”
An S-GRN board of 6” has an actual dimension of how much less?
3/8
An S-Dry board of 8, 10 of 12 has an actual size how much less?
3/4”
An S-GRN board of 8, 10 or 12 has an actual size of how much?
1/2” less
What angle must the grain be to be considered edge grain?
Greater than 45 degrees
Describe “Plain sawing”
When the boards are cut through the FULL width of the log.
WHat abbreviation is used for 1x10 re-sawn boards?
S1S2E
What does S-GRN stand for?
Surface Green
What is machine stress-rated lumber?
Lumber that is passed through a device that measures how much the actual piece of lumber will bend or flex under a given load.
Where is machine stress-rated lumber used?
Critical members are engineered using wood-trusses.
List the four grades used with lumber classified as “light framing”
Construction, standard, utility and economy.
List the four grades used with lumber classified as “structural joists and planks”
Select Structural, #1, #2 and #3.
What are the actual dimensions of a 2x6 that’s surfaced dry
1 1/2 x 5 1/2
What are the actual dimensions of a 2x8 that’s surfaced green?
1 9/16 x 7 1/2
What is the density of western red cedar?
310 to 340 kg/m cubed
What is the density, relative to water, for a hemlock log that sinks to the bottom of a lake?
Greater than 1.0 kg/M cubed
How is a KInk defect caused in a length of wood?
The deviation of straightness os caused by a large knot in the length of the wood
When is a crown defect in a joist desirable?
Installation of joists to counteract live and dead loads.
What happens in a diamonding defect?
The sides of timber are no longer square to each other.
In a stack of lumber, which boards are less likely to be warped?
Boards at the bottom of the stack, under weight of the other boards.
What is a split?
Separation of wood which happens when wood cells tear apart.
What is a shake?
A lengthwise separation of wood. Usually occurs between or through the rings of annual growth. Shake can be caused in standing trees when there is alarge amount of movement caused by wind.
What is a check?
A separation of the wood, which normally occurs across or through the rings of annual growth. It’s usually the result of seasoning when there is uneven shrinkage.
What is a pith shake?
A pith shake extends through the growth rings from or through the pith towards surface of a piece.
Pith shake, heart shake, star shake or heart check.
What is a ring shake or cup shake?
Occurs between the growth rings and partially or wholly encircles the pith.
What is wane?
MIssing piece of wood on the edge corner of a board.
What is a pitch?
A pitch is the accumulation of resinous material. It usually collects when wood in the tree is damaged by wind or lighting.
What is a pitch streak?
A well-defined accumulation of pitch in the wood cells, in a more or less regular streak. It should not be confused with dark grain.
What is it when a wood is “stained”
A marked variation from the natural colour.
How does decay occur? (rot)
All decay results from the invasion of a single class of plant called Fungi. Once MC% is less than 20, no further rot occurs but the wood will remain damaged.
True or False: Sap-Stain fungus will reduce the structural strength of lumber.
False
True or False: Rot Fungus fungus causes the wood to deteriorate.
True.
Does Brown Rot occur after the wood has been dried?
Most does not.
How does dry rot begin to occur?
Lack of ventilation, high moisture content, heat (aboe 15 celsius)
What are three common types of rot?
White Rot, Brown rot, and dry rot
List three precautions that should be taken to prevent rot?
1) MC % less than 20%
2) Wood in service is properly ventilated
3) Treat wood to prevent fungus attack when placed in areas of high MC %
Name the three causes of manufacturing defects in lumber
1) Improper season techniques
2) Improper handling
3) Improper storage
What causes a board to warp?
Incorrect seasoning or naturally due to grain
Which insect leaves piles of sawdust and makes a rustling sound in walls?
Carpenter ants
Which insect travels in specially constructed mud tunnels?
Western subterranean termite
Which insect bores small round holes in wood?
Powder-post beetle
Which type of defect occurs when particles of wood are broken below the line of cut?
Chipped grain
What is machine burn?
Darkening of the wood due to machine knives or rollers getting overheated when pieces are stopped in the machine.
What causes chip marks?
Occur when dressing - when shavings or chips become embedded in the material.
A sheet of T&G plywood is how wide?
There is a reduction of width. 47 1/2.
What is cross banding?
In the process of making plywood - layers of veneer are laid at right angles to one another
For maximum strength, how should plywood be installed?
Installed with the length of the sheet (face grain) - across its supports.
What does painted edge on OSB do?
Protect from moisture.
Which kind of OSB grade is used for framing?
OSB 0-2 is equivalent to plywood. OSB 0-1 is equivalent to a wafer board.
True or False: OSB T&G will cover a full 4-foot width.
True
What is Waferboard?
Waferboard looks similar
used for floor, wall and roof sheathing, but not as strong as OSB 0-2
How strong is particleboard?
It’s one of the weakest composition boards
What is MDF mainly used for?
Stronger and denser than particle board
Used to make many interior mouldings
What is hardboard?
Denser than MDF, made from exploded wood fibers that are glued together
Used for clipboards, pegboards and drawer bottoms
What is a cross laminated timber?
Engineered panel made similar to veneers in plywood. often an architectural feature
What is Glue lam?
Structural, beams or columbs.
What is laminated Veneer Lumber?
LVL looks like plywood beams, except all the plies have the grain running in the same direction. Made of multiple layers of thin veneer, this lumber is very strong and stable and can span farther than sawn timbers. LVLs can be used for rafters, headers, beams, joists, rim boards, studs and columns.
Similar to LVL, except instead of full sheets of veneer, strands of veneer are laid in parallel formation and glued together. Same use as LVL.
What is Parallel Strand lumber?
Structural Insulated Panels, what are they?
SIP consist of insides and outside panels with rigid insulation between. They are often plywood or OSB. Panels can be splined together to create walls, floors and roofs.
Name Two kind of Sheathing Panel
Plywood and OSB
Why is it easy to make a 4’ x 12 ‘ sheet of OSB but difficult to make it from plywood?
OSB is manufactured in very large sheets over 12 ‘ x 12 ‘ whereas logs for plywood are cut just over 8’
What 2 features do T&G have to help them resist water damage?
Painted edges, drainage holes along the tongue
grade plywood is used for sheathing? Is it Sanded?
Not for sheathing grade.
What must fasteners resist?
Both withdrawal and shear forces
What is withdrawal strenfth of a fastener?
It’s ability to resist being pulled out.
To increase: anglng nails in opposing direction
Stagger nails.
Ring Nails, spiral(ardox), and galvanized increase withdrawal compared to bright nails.
What is shear strength in a nail?
The ability to resist lateral movement.
Ex a ledger which supports a deck joist must be able to resist.
EX Hangar nails with thick shank
Bright finished nails are used for what?
GC, including framing and sheathing. Rust in weather.
Galvanized nails are used for?
Exterior use, resist rust and corrosion. Thick coating of zink produces very rough surface which increases nail’s holding power.
Electro-plated galvanized nails are used for?
Not as resistant to rusting and are designed to be used where they will not be directly exposed to the weather.(Roofing and drywall)
What qualities does a phoscoated nail have?
Dark or black, better resistance to moisture and withdrawal than bright finish nails.
“Phoscoates nails are also made specially for spf application”
What qualities does a phoscoated nail have?
Dark or black, better resistance moisture to moisture and withdrawal than bright finish nails.
Mainly use for drywallor SPF lumber.
What is a heat-treated nail used for?
Treated to make them stronger and stiffer. They may also have a higher carbon content. For hard surfaces such as concrete.
Describe a hanger nail
Stuff and short common nail, offer maximum resistance to shear when used with joist hangers. bright or galvanized.
What is the advantage of an ardox nail?
Strong holding power (50 to 200 % greater than smooth-shank) but shear resistance is lower
What are box nails used for?
Thin wood to prevent splitting. Not normally for framing.
What kind of nail would you use in marine construction, or when maximum corrosion resistance is required?
Stainless Steel Nails
How much longer than the thickness of the deck subfloor should a deck screw be?
1 and 1/4”
Two reasons to use a coated nail are:
1) Prevents corrosion 2) better holding power
What type of nail is best suited for exposure to the weather?
1) Stainless steel
2) Hot-dipped galvanized
Name three types of nails that have a better withdrawal resistance than a bright common nail?
1) Ardox 2) Ring 3) Galvanized
What special safety concerns are there for driving concrete nails?
Wear safety glasses.
When using construction adhesive, you must completely nail the sheathing before:
The adhesive sets up.
What kind of fastener must be used with ACQ-treated lumber?
Corrosive resistant
What is the first step when choosing framing hardware?
To determine the type of material being used.
IN what locations is column anchorage especially important?
Locatiosn where high winds can create extreme up-lifting forces.
IN what locations is column anchorage especially important?
Locations where high winds can create extreme up-lifting forces.
What should be done when installing joist hangers for an engineered floor?
Double-check joist hardware is used according to the engineering drawings.
What is a structural strap used for?
Wall bracing
What is a connector plate used for?
To reinforce joints or to splice beams.
How are seismic hold downs extended?
Threaded rods and coupling nuts
What quality must framing hardware have when used with preservative treated lumber?
Corrosion resistant.
What are the qualities of Springwood? (early wood)
Is formed in the early part of the growing season when growth takes plus rapidly.
Characterized by large, thin-walled cells and the material is more porous and weaker than wood formed later.
RAPID GROWTH = WEAKER and THINNER
What are the qualities of Summerwood? (aka latewood)
Produced late summer, fall and winter. Consists of small, thick-walled cells and is greater in density and strength than springwood.
When a new layer of wood is added to the diameter of the tree every season, they are called?
Annual growth rings.
How many annual rings per inch should structural lumber have?
6 rings per inch.
How much MC % should lumber used for framing have?
15 - 19 %
Water in the cell cavity is called bound water or free water?
Water in the cell cavity is called “Free water”
Water in the fibres of cell walls is called free water or bound water?
Bound water
When a dry piece of wood is exposed to moisture, the cell walls absorb moisture until they become totally saturated and can hold no more. What is this called?
Fiber Saturation Point, or FSP.
Once FSP is reached, additional moisture accumulates in the cell cavities as free water.
FSP is reached at mc % of 25% to 30%
When wood dries, shrinkage does not take place until when?
All the FREE water is gone from the cells.
Wood used in construction must be uniform in size and grade, who regulates the sizes and grades?
NLGA - National Lumber Grade Authority
Nominal sizes are done when?
After rough cutting
Actual sizes are done when?
After re-surfacing
What is a dead knot?
Forms after a branch dies. Happens in lower branches that have been deprived of light by dense foliage around them.
What is Sap-strain dungus?
Stap stain fungus causes wood to turn blue but has no effect on structural strength.
Feeds on the contents of the wood cells without damaging.
What is Rot Fongus?
It feeds on both the contents of the cells AND the cell wall themsleves.
What is brown rot?
Brown rot attacks the cellulose that makes up the walls of the wood cell.
Reduces wood to brittle, brownish material.
Not persists after wood dies
What is white rot?
Attacks cellulose and cell walls and the lignin that binds the cells.
White rot is also called white speck, which is the initial stage of white rot.
Infection shows as a soft, pulpy mass of whitish material, which has no structural strength.
What is dry rot?
Dry rot infects trees after they are felled and can continue to thrive after the lumber-drying process. Dry rot often turns up after wood is put into service in poorly ventilated areas such as cavities beneath floors.
What is dry rot?
Dry rot infects trees after they are felled and can continue to thrive after the lumber-drying process. Dry rot often turns up after wood is put into service in poorly ventilated areas such as cavities beneath floors.
What is a western subterranean termite?
Feeds on wood and consequently can be very destructive to wooden structures.
Live in wood in contact with the soil but will travel inside spec mud tube to feed on the wood above the soil. Mostly damaging basements at ground level.
What is a pacific damp wood thermite?
What is pacific damp wood thermite?
Pacific damp wood thermite attacks wood with a high MC %.
Produces long flat tunnels in wood. The entire inside of infested wood is eaten, leaving only a thin outer shell of wood.
What is a powder-post beetle?
Powder post beetle bore small round holes 2-3 mm in diameter throughout the wood. These are the exit holes of the adult beetle.
Inside the tunnels are filled with sawdust and excement. Fine powder may be observed coming out of the holes, or in piles under the holes.
What is a toeredo worm?
Destructive pest of submerged timber. Softwood can become riddled with tunnels within months of being in salt water
