Timber Flashcards
Timber in construction is used for 2 things which are;
1) Structural use
2) Non structural use
Examples of structural use for timber in construction are; (4)
Frames
Joists
Trusses
Bridge
Examples of non structural use of timber in construction; (3)
Window frames
Doors
Furniture
There are 2 main types of timber which are;
1) Softwood
2) Hardwood
The properties of softwood are; (3)
1) Grown quicker / easier therefore more economical
2) Low density
3) Easily worked with
The properties of hardwood are; (4)
1) Harder than softwood
2) Stronger than softwood
3) Durable
4) Higher resistance to insect attacked and rot
Advantages of timber are; (8)
1) Wide range of timbers with various densities, strengths, colours, grain patterns etc.
2) Easy to work with
3) Resistant to mild chemicals
4) Readily available (if managed correctly)
5) Insulates against electricity and heat
6) Sustainable and environmentally friendly (if managed correctly)
7) Can be relatively cheap compared to other materials
8) Strong
Disadvantages of timber are; (5)
1) Combustable material
2) Susceptible to insect attack
3) Hygroscopic material - absorbs and expels moisture - shrinks and swells with humidity and moisture content changes
4) Strength not the same in all directions
5) Cannot be manufactured to a particular spec like concrete?
Some reasons for selecting timber as a material in construction are; (3)
1) Availability - easy to access large quantities
2) Easy to handle - lighter than other materials, can be cut into smaller sections and re-assembled
3) Durability - if well preserved
Hardwoods come from trunks of trees which have ________ leaves
Broad
Softwoods come from trunks of trees which have ________ leaves
Needle
Examples of hardwood trees are; (4)
1) Ash
2) Oak
3) Teak
4) Iroko
Examples of softwood trees are; (4)
1) Pine
2) Fir
3) Larch
4) Spruce
Differences between hardwood and softwood are; (6)
1) Cost - hardwood is more expensive
2) Time to grow - hardwoods take longer - softwoods quicker and easier
3) Density - hardwoods are denser
4) Strength - hardwoods are stronger
5) Durability - hardwoods are more durable
6) Sustainability - softwoods are more economical
3 parts to structure of tree are;
1) Root
2) Trunk
3) Crown
The root of the tree; (2)
1) Absorbs mini raps and water from soil
2) Acts as anchor to resist wind loads
Trunk and branches of a tree; (3)
1) Transports minerals and water from root to crown
2) Provides strength / height
3) Provides timber products
Crown of a tree; (3)
1) Provides cover
2) Absorbs light and rain water
3) Allows photosynthesis to take place
Hardwoods come from _______ leaved trees, most of which are ___________
Chudley (2011)
Broad
Deciduous (meaning = shedding its leaves annually)
Hardwoods are generally used for; (2)
1) Furniture
2) Fixtures
Softwoods are from __________ trees with _______ shaped or ________ like leaves
Coniferous
Needle
Scale
Softwood is commonly used for; (2)
1) Construction elements
2) Framing
The 4 stages of the manufacturing process associated with timber are; (4)
Sawing
Seasoning
Chemical Treatment
Packing
Seasoning is the process of;
Intentionally reducing the moisture content of timber
The purpose of seasoning is; (3)
1) Reduce moisture content
2) Prevent from fungal attack
3) Make the timber stronger and easier to use, transport, glue, paint and preserve
The two types of timber seasoning are; (2)
1) Air seasoning
2) Kiln seasoning
Air seasoning is the process of;
Stacking the timber in the open air for drying naturally
Air seasoned stacks of timber are stacked in the following manner (6 points)
1) Separated with horizontal spacers to allow full circulation flow of air around stack
2) Stacked and a safe and stable manner
3) Ends of boards are sealed to prevent too rapid drying out via end grain
4) Stacks are raised well clear of ground(free of rising damp, vegetation etc.)
5) With overhead cover to protect from direct sunlight and driving weather
6) In UK further seasoning done inside in heated and ventilated buildings (as can only reduce moisture to about 16-17% naturally)
Kiln seasoning is the process of
Artificially drying timber in a controlled environment
An advantage to air seasoning is;
Cheaper than kiln drying as no energy used, less labour time