Flashcards in Wood Deck (63):
how much % of world's wood comes from North America?
t or f wood takes less energy to produce than that of steel, cement, copper and aluminum
what is the most economical choice for building materials
what is wood technically?
-dead or dying cells below the cambium layer
-made of small fibres that are long and narrow
what strength is wood strong in?
what bonds the cells (cellulose) together in wood?
what % makes up wood?
-60% cellulose ; small long narrow cells
-28% lignin; glue that holds all together
-12% sugars and extracts
what are characteristics of hardwoods?
-oak, maples, birch ect
-cells thicker, denser and stronger
what are characteristics of softwoods?
-spruce pine fir and cedar
-cells are thin, less dense and weaker
what is the pith of the tree
- centre, where earliest growth occurs
what is the heartwood?
dead portion of the tree located towards the centre
-provides structural support, more resistant to rot
what is the sapwood?
-contains the living portion of the tree: sap
what is the cambium ?
growth area of the tree
what is the springwood ?
rapid growth, thin walled cells
what is the summerwood?
slow growth, thick walled cells
when does the growth year start/ stop of a tree?
-stops when tree drops leaves and goes dormant, starts when new leaf development
t or f, all trees have growth rings
-false; only occurs when climate limits growth part of the year
characteristics of cedar
-tannins, resists rot, easy to work with, food look, colour and aroma
uses of spruce ?
-farming, must have preservatives for outdoor use
uses of pine?
-needs preservatives for outdoor uses
what is the hardest softwood?
characteristics of hemlock
-good rot resistance, poor availability, hard to work with
characteristics of fir?
-even grain, needs preservatives for outdoor use
-good for structure, rot resistant, poor availability= expensive
characteristics of hardwoods?
-good for furniture, expensive, will rot and doesnt receive preservatives well
what are 4 natural destructive agents to wood?
what 4 things need to be present for decay ?
what is green wood?
-term for freshly cut or 'live' wood
-moisture content over 32%, could be as high as 100%
what is seasoning of wood?
-process of removing moisture from wood
-reduces moisture content to make stronger
what is the fibre saturation point
- as moisture content of wood is reduced from seasoning process, water removed from cell cavities and voids
-any remaining moisture is contained within cells = fibre saturation point
what is the moisture content at the fibre saturation point?
-point where cell shrinkage and reduction of wood column begins
what direction does wood shrink? by what % at the end of the seasoning process?
what varies as moisture content varies?
-ability to resist and decay
when is wood considered 'seasoned wood'
describe natural method of seasoning wood?
- undercover/ out of direct sunlight and weather
-open sides to env't
- properly / neatly stacked off the ground with spaces b/ween layers --> air flow
-takes min 1 year
what is kiln dried?
kiln dried 80- 100C for 24-48 hours
what is dressed lumber ?
-process of planing down the lumber to its finished dimension leaving it with smooth / dressed surfaces
when is the best time to dress wood?
- after the seasoning process so that most of the woods shrinking would already occurred
-accurate dimension--> wood done shrinking
what would a piece of lumber be stamped with if it was dressed after seasoning?
what would a piece of lumber be called if it was dressed on green wood?
what is the most effective way to prevent rot and decay
add preservative --> Pressure treating
describe pressure treating process
- heat up wood to allow for better penetration than inject/ spray chemical on wood at high pressure
name 2 common chemicals used in pressure treatments?
- CA (copper azole) and ACQ (sodium borate)
which chemicals should you avoid pressure treating with?
- creosote (railroad ties)
-pentachlorophenol (hudro poles)
-both petroleum based
what is the difference between wood preservatives and coatings?
- coating provide protection but don't preserve
give 3 ex of wood coatings
stain, paint, water coating
what other benefits are there for coating wood?
1. reduce effects of UV
2. retard moisture fluctuations
3. provide increased resistance to abrasion
what is grading lumber
- gov't agencies that control grades of lumber
-measurement of amount of 'clear wood' in a piece
what is 'select wood'
- no large or loose knots and no less than 85% clear wood
name 4 common grades of lumber
3. light framing
who reinforces the grading of lumber?
- National Lumber Grades Authority (NLGA)
differences between western red cedar vs eastern white cedar
red: stronger psi
-higher shipping cost
-high ability to hold fasteners
White: -smaller, lots of knots
-cheaper to ship
what are common sizes of lumber ?
1x2, 2x2, 2x4, 2x8, 2x10, 2x12
8, 10, 12, 14, and 16 lengths
what lengths do 1x 6 fence boards come in?
4, 5, 6, 8
describe how EcoVantage wood is produced?
no chemicals, wood treated with heat and steam
-processed over 400F
-eliminates sugars and starches
what are pros of ecovantage wood
- natural wood product
-free toxins and chemicals
-no resin, sugars, low moisture
-30 year warranty
key properties to EcoVantage wood
-warp. twist, expansion substantially reduced
-biological durability improved
what is pervious concrete?
-'No fines concrete'
- concrete with interconnected voids to allow water to pass through
-near 0 slump
-course aggregate, cement, admixtures and water
what date was pervious concrete invented?
1852, became popular after WW2
what are pros of pervious concrete?
- reduced upfront infrastructure cost
-reduce burden on again infrastructure
-controls flooding and erosion
-reduced ice pavement build up
how does pervious concrete improve water quality?
- removes 80% suspended solids from rainwater
-contains hydrocarbon within system
, then broken down over tiem by micro organisms
what is hydromedia technology ?
- 2nd generation High Performance Pervious concrete
-uses sufficient paste to coat and bind the aggregate particles together to create a system of highly permeable, interconnected voids that drains quickly
-doesn't require heavy compaction