Purpose
ensures uniform loading over ground
eliminates capillary void for damp
enables fill to required level
clean dry and level working surface
Includes…
brick/tile, clinker, gravel, quarry
waste, shale
Must not include…
plaster, timber, thermal block
General insulation for walls or roofs can come in a variety of formats…
Loose Fill is made up of polystyrene beads or cellulose fibre and can be poured into spaces such as cavities.
Bat insulation is a semi-rigid insulation board often made up from compressed cellulose fibre, mineral wool or glass fibre.
Blanket insulation is [...]
Plywood is constructed using thin (above 2mm) veneers of wood sawn off logs. A sheet is laid flat, covered with adhesive and then another sheet is placed with the grains at right angles. This process can then be repeated to get 3, 5, 7 or more plywood, with all thicknesses in odd numbers as the [...]
Advantages
Very strong in tension
Considerable compressive strength although box section is strongest
Tension and compression act on only top and bottom of ‘I’ section so holes can be drilled through to reduce weight and provide utility access
Speed of erection
Disadvantages
Time to site – slow
Cost
Loss of strength in fire although it can be protected by intumescent paint or foam
Corrosion
Skilled [...]
Bricks generally conform to very standard dimensions of…
Length – 225mm inc 10mm horizontal joint
Height – 75mm inc 10mm vertical joint
Width – 100mm
However, some bricks are of a different size. During the metric-imperial change over 300mm bricks were produced yet it was discovered they proved difficult to practically use for builders.
A – Stretcher
B – Header
C – [...]
Advantages
Good compressive strength
Short lead in time
Disadvantages
Bulky
Curing time
Cancer, carbonation, corrosion, acid rain
Accurate set out needed
Skilled labour for shuttering
Workmanship risks
Early Egyptians and Greeks had only stone lintels, which had a limited tensile strength so distances spanned could only be relatively small. The Romans developed the semi-circular arch. Load is transferred down through constant columns to ground. As the arch is loaded, the stone will tighten up and bear greater load.
Advantages
Good tensile strength (also compressive along grain, eg end loaded)
Short lead in time
Familiar material to workforce
Flexible in construction
Disadvantages
Limit to sizes available
Not stable
Beetle, decay and fire?
Vulnerable to poor workmanship
Too easy to adapt
Maintenance cost
Strongest woods (hardwoods) also slowest to grow
Concrete is strong in compression, however is generally weak in tension. Therefore when a load is placed upon it it may bend. To make sure this doesn’t happen, steel reinforcement is put in on the tensile face, normally the bottom edge if a floor or beam.
Tension can also occur outwards, so for example a basement [...]
Advantages
Good compressive strength
Familiar material to workforce
Ethnic – of the locality
Disadvantages
Poor tensile strength
Some stones decay
Need for skilled workforce
Maintenance cost – discolouration/cleaning
Sedimentary stone is not formed under pressure but in layers and can split off if vertically loaded. This can, however, be useful – eg slate
Some stone, such as marble, is too expensive for construction although may [...]
