So if you’re in the building industry in Australia you’ve probably noticed by now that the sizing and spacing of structural members isn’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 to 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100 I think we’ll make it easier for ourselves, use our modern materials more efficiently and finally close the door on outdated imperial standards.
Join Matt Cornell as he checks the drawings for a single storey concrete masonry (bessa block) home to be built in a cyclone region. He goes through the process of checking a set of structural engineering drawings with some tips for checking and good construction.
Today we’re going to go through the process that I normally follow when I’m checking a set of engineering plans.
So a job comes into – a set of plans come into the office and they’ve asked us to do the engineering.
One of my engineers has done up some engineering drawings.
Here you can see the engineering, the AutoCAD file here. They’ve set up a form 15 ready for me to fill in. I’m doing the checking.
So a lot of the works already been done. There’s a checking folder already as you can see, so first thing I’m going to do is is check to see what the client has actually asked for.
G’day. This is Matt Cornell from Cornell Engineers. This is a waffle slab inspection that we did a little while ago and I wanted to go through and put some words to it to let you know what we’re looking at during this inspection.
So here we go coming in from the front I’ll just pause it there and explain some of these things.
The white things that you can see are the polystyrene waffle pods they come in about a metre by metre squares they’re sort of semi- hollow underneath. They’re not solid polystyrene but on top they’re solid. The space between waffle pods is about 110mm wide.
Is it because your house has cracks in it? Is it because your neighbour had their house underpinned? Is it because you don’t have time and you need your house fixed NOW? Is it because some random salesperson said you do?
Have you even had your house assessed by an engineer yet?