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Timber is used in many situations. It
is used extensively in the construction and furniture industries.
Mainly it is used for:
(1) joinery.: windows and doors
(2) furniture: tables, chairs, presses, cabinets etc.
(3) structural timbers: that is, timbers which must take a load,
e.g. rafters, joists and flooring
Structural timber must be graded so that architects,
engineers and builders can be sure that the timber they are using
will carry the loads designed for it. There are 2 methods of
grading:
Visual Grading
Specially trained people check for defects in each piece of timber,
such as large knots, splits, shakes and checks.
Machine Grading
The lengths of timber are fed into a stress-grading machine.
Rollers automatically apply a load to the piece of timber and
the machine then measures how much the timber bows or deflects.
The more the timber deflects the weaker the wood. The end of
each plank is marked according to its stress-grade. There are
2 stress grades:
(1) General Structural (CS)
(2) Special Structural (SS) |
