So if you’re in the building industry in Australia you’ve probably noticed by now that the sizing and spacing of structural members aren’t exactly metric. I mean, we’re working in millimetres and all but have you noticed we still bow to imperial measurements in nearly all structural framing?
Here is how pervasive the imperial system is in our construction industry:
- 75mm x 50mm studs are really 3 inch x 2 inch studs in imperial
- (70mm x 45mm studs are just the seasoned timber equivalent of 75 x 50)
- Roof frames are at 900mm (3 feet) or 600mm (2 feet) centres
- Studs are at 450mm (1.5 feet) or 600mm (2 feet) centres
- Residential wall heights are commonly 2.4m (8 feet), 2.7m (9 feet) or 3.0m (10 feet)
- Windows are 900mm (3 feet), 1200mm (4 feet), 1500mm (5 feet) etc wide
The list goes on.
Why are we hanging on to these old imperial dimensions when we turned metric many, many years ago? Wouldn’t it be easier for set out, planning and ordering to be working in metric?
Our materials are made better and are stronger and more consistently than ‘the old days’ when these systems were first put in place.
- Why can’t studs be placed at 500mm centres instead of 450mm centres?
- Why don’t we have trusses at 1000mm (1 metre) centres?
- Why don’t we have wall heights at 2.5 metres and 3.0m standard?
- Why don’t windows come in 500mm width increments to suit metric stud centres?
So I’m calling out to industry, to suppliers, to product technical advisors and other structural engineers. Let’s make the move to metric in the construction industry. It doesn’t have to be overnight, but when we learn to work in metric numbers, in easy multiples of 10, 50 and 100 I think we’ll make it easier for ourselves, use our modern materials more efficiently and finally close the door on outdated imperial standards.