Canadian Wood-Frame House Construction
provides both metric (SI) and imperial units. The National Building Code of Canada
uses metric units and these govern whenever strict interpretations of Code requirements are required. Imperial units of measure
(feet and inches) are still commonly used for wood-framing materials and house construction technology.
Imperial sizes for lumber are
nominal sizes (the rough sawn sizes before planing and dimensional changes resulting from drying). For example, a wood member with a nominal size of 2 × 4 in. has a finished size of about
11⁄2 × 31⁄2 in. The metric dimensions for lumber are
actual sizes (for example, 38 × 89 mm).
Every reasonable effort has been made to provide accurate conversions of metric dimensions to imperial equivalents; however, it remains the responsibility of designers
and builders to comply with building code requirements.
As an example of the national building code, here is a excerpt from the code.
To agree with the National Building Code,
the metric spacing of wood framing members
is expressed as ‘soft’ conversions from the actual imperial dimensions. For example, spacing of
12, 16 and 24 inches on centre are converted
to 300, 400 and 600 mm on centre, respectively. In order to suit the imperial sizes of common 1220 × 2440 mm (4 × 8 ft.) panel products, such as gypsum board, OSB and plywood, the actual spacing of framing members has been adjusted
to approximately 305, 406 and 610 mm on centre, respectively.
Canada is metric. All stength testing and certification of lumber fabricated and sold in Canada is done using metric units. Try to find a 3/4" thick of plywood made in Canada. Impossible. They are fabricated using metric sizes.
I think Festool is making a big mistake.
Canadian Wood Council
I remember when I did my thesis for my Structural Engineering degree, 25+ years ago, that all lumber, trusses, gusset plates etc, were metric and all findings were published in metric.
I could go on for ever on this topic but I wouldn't. Festool please re-think your decision for Canada. We are not the US.
My 2 cents worth.
Cheers
JC