Timber Flashcards
Anatomy of wood
- 60% carbon
- 40% oxgyen
- 6% hydrogen
is also made up of pigments, oils, resins which the n determines smell and colour
Describe Hardwood including properties
20 % decidous tress Oak, Teak, Mahogany ecpensive good fire resiatnce tight grain darker
Describe softwood including properties
80% Coniferous trees Pine, spruce, fir unexpensive lighter looser grain
Which way is wood strongest?
parralel to the grain
What does Anisotropic mean?
different properties in different directions
Process of milling timber
de-bark log
rounded side are send to a chipper
sections are used from the outside has fewer knots
What can logs be turned into?
sawing - timber
peeling - verneer
stranding - strands
Moisture in wood - types
green
semi-dry
dry
laminated timber
lay the same way
longer spans
heavier loads
more complex shapes
Cross laminated timber
each layer is laid an opposite way
Veneer
cut into slieces
can be either soft or hard wood
Laminated venner lumber (LVL)
resin and same oreientation
Timber grades
machine strength grading
bending strength and stiffness
density
visual strength grading (distortion, wane, shakes, fissures , knots)
Benefits of timber
versatile durable strength thermal insulation acoustic insulation tensile strength ease of manufacture resistance to high temperatures natural appearance cost health benefits
Environmental impact of timber
climate - mitigrating properties lowest carbon footprint energy -are sent no waste / by product renewable
origins of softwood
38 % UK produced
62% imported
origins of hardwood
7% UK produced
93% imported
origins of particle board
68 % UK produced
32% imported
origins of plywood
0 % of UK produced
100% imported
origins of fibreboard
43% UK produced
57% imported
Trade-off of using timber
shrinkage and swelling
deterioration
- biotic agents = decay (fungi, bacteria, insects)
- Abiotic agents = weathering (sun, wind, water, certain chemicals)
lock of components
length of spans ‘limited’
