More Questions about the Metric System - House Construction

Maybe this could have gone into the other thread, but I’ll start it as a new one.

An older complaint that I heard about the metric system was that when the US would finally go in for more complete conversion, there might be various incidental PITA issues coming out of the, er, woodwork. Wood frame construction is very common in the US, particularly here in the west. Typical stud spacing for walls is 16 inches; I’m aware that it can go up to 24 inches in many circumstances.

Plywood and gypsum wallboard sheets come in various compositions and thicknesses, but a very common sheet size is 48 inches by 96 inches, or 4 feet by 8 feet. This fits quite well with the common stud spacing, don’t you know.

Many of you know where this is going. When the US goes more completely metric*, stud spacing will likely change to 400 to 600 mm. Four studs at 400 mm will then be 1200 mm outer to outer stud center, or about 47-1/4 inches.

Will that cause issues with getting the current common size of plywood and wallboard sheets to ‘fit’ properly? If the plywood sheets are likewise reduced in size, won’t that cause a problem in retrofitting the older homes with the slightly greater spacing?

Or is this just something that carpenters would just work around?

How do you deal with this in Canada?
*Well, for one thing, we are partly there, what with soda and liquor sold by the liter, and metric auto wrenches, and 5 k runs, and such. That, and I think that someday we’ll finally get tired of hassling with 5,280 feet per mile and 43,560 square feet in an acre, and all that.

Here in Canada, where our largest trading partner for many commodities including softwood lumber uses feet and inches, we still measure most building materials in feet and inches.

Well, no, I’m not surprised.

Things like the 2x4 are universal across many “metric” countries. Which of course is nominal, they’re something like 1.5 x 3.5. The US could easily still make 16" studs forever, but call them 41 cm or whatever. Canada still gets by using Letter sized paper instead of A4.

Not construction, but I think monitors are inches pretty much everywhere. Also the other thread is too long for me to ready, and probably IMHO, but I’d think miles are the last thing to go. The vast number of road signs and mile markers are a daunting thing to replace.

I was wondering the same thing a while ago, and asked an English tourist. He said they still use the same physical sizes, but describe them using the metric system, so for instance they would still build using an 8 foot long board but would call it a 2.4 (or whatever) meter board.

It would probably be called a 2400mm board, which is more confusing because it implies a level of precision that it doesn’t have.

As if calling a 1.5" x 3.5" piece of wood a “2x4” isn’t also confusing…

Our plywood still comes in 4x8 sheets (well,2440mmx1220mm), and we are in all ways completely Metric. However, we don’t really use frame construction much, here in South Africa.

It has taken a long time for wood sises to be metricated here. Back in the 80s I was buying 5 metre long 2"x4"s.

Part of the problem of changing these things is that the machinery used in timber yards and workshops lasts a long time and is calibrated in inches. If I go to the DIY store to buy a sheet of ply or wallboard it will be marked up as 2440 x 1220, which is a straight conversion from 8’x4’.

Shipping pallets here come in two sizes: Euros which are 800 x 1200 or the old standard UK size which was 48"x36" and is now 1200 x 1000 mm.

Metrication started seriously here way back in the 60s; joining what was then The Common Market gave it a boost since much of the ‘common’ legislation was in metric units. It still has some way to go yet and I think it will take a couple of generations before Imperial units go the way of rods poles and perches.

Australian building, which also involves lots of timber construction went metric and the world did not end and the cows kept giving milk.

It feels like people are lining up excuses and are well down on page 2, and they’re getting pretty flimsy. I suspect its not long before we hear about the potential dangers of hitting an inch nail with a metric hammer.

Stud sizes stay the same, but eventually building standards are documented differently. The first step is translating the numbers. the second step normallising the ranges, so a 12" spacing becomes “between 300 and 310 mm” instead of “292 to 318”. The third step is when you decide to actually change something for some other reason “we don’t actually need 12” there, we could make it cheaper at 18", and it would work just as well." At that point your new standard is 450mm +/- 10mm

Aus metricated years ago, and it wasn’t the second coming of Christ: it fundamentally didn’t make anything easier or better. It marked an intended trade re-alignment, from Britain to the EU, with dog-whistles of anti-Americanism, but that was more political than practical: it’s not like Britain or the EU noticed.

Construction industry in Pakistan is still mostly in imperial units.

In Thailand, wood boards are measured with inches for thickness, feet for width, and meters for length. We’re read fo everything! :smack:

As MrDibble says we don’t go for frame construction. We use brick, but still in odd sizes when given in millimetres. The standard brick is the South African Imperial measuring 222mm [l] x 106mm [w] x 73mm [h]. Based, as its name suggests, on some colonial era UK standard.

Home construction is the last bastion of the inch system. It is the only place I know that uses feet, inches and fractions of an inch. Commercial construction uses inches and decimal inches as does all machining.


Certainly in Canada wood is still sold by the inch and foot. A 2 by 4 is still whatever it is (1.5" by 3.25" IIRC). But I have an amusing story to tell you about Europe. A friend of mine is from Northfield, Minnesota where everyone speaks Norwegian (supposedly, but he does anyway) and lived for a couple years in Oslo. He needed a 2 by 4 and went to a lumber yard and ordered a 5 by 10 cm length of wood at the order desk. The clerk picked up the phone and asked for a 2 by 4 to be brought up from the depot.

Practically everything else here is metric. Road distances and signs, temperature, milk containers, you name. One big exception is people’s weights and measures. My doctor’s scale still weighs in pounds and the height scale is in inches. I expect that will take a good long time to change. His practice started after Canada went metric.

Not only monitors: screens, but (at least in the EU) they give the diagonal in inches and also the diagonal, width and height in mm.

NZ home construction is predominantly wood frame based so similar to the US. Construction timber is pretty much sold in all metric units, so 100 x 50 studs, but many people still refer to them as 4 x 2. Dry wall sheets are in 1200 x 2400 or 2700 sizes, as are plywood sheets. Stud spacing normally at 400 centres. Note that dimensions are given in millimetres and lumber lengths are in metres.

… in other words, from what the majority of these posts have said, change is minimized by declaring metric standards that are magically more or less compatible with the old standards, and everyone carries on.

What you might call “radical metric” construction - changing the dimensions of a 2x4, changing the dimensions of a sheet of plywood - isn’t necessary.
(I’m all for “radical metric” on the paper sizes though - that one really does help, especially with photocopies.)

The 1:sqrt(2) ever repeating rectangle is pretty cool, unfortunately two different committees produced two paper sizes in the US at the same time and the German DIN standard wasn’t defined until a couple of years Later. I doubt that the US would have adopted a German standard at that time in history anyway.

Of course everyone still does inch based margins, and point sizes are way more painful in multiple ways due to multiple reasons, but it would have been nice to have a paper size where the actual aspect ratio was considered and not just trimming waste costs.