Roof Issues


Designer100
 Share

Recommended Posts

Interestingly, I believe the only countries in the world that haven't adopted the metric system are Myanmar, Liberia and....oh yes...the USA.

 

Besides Imperial has a nice ring to it.

 

 

Rich,

In the US, I think Imperial is the incorrect term - they should probably be referred to as the Customary System - but who really cares!

Link to comment
Share on other sites

Where I've done plans in metric (Central America) wood is simply not a building material, so these material considerations are mostly mute. I would be interested in knowing though where it is still used, how they dimension their wood materials. Is a 2x4 (nominally 1.5" x 3.5") called a 50.8 x 101.6 (38.1 x 88.9)? Not really sure, but wood is not a common material in most parts of the world, we just happen to have %^&$ loads of it here.

Link to comment
Share on other sites

It actually would not be that hard really. From a design perspective, our 'putters don't much care if we enter metric or imperial units, so no issue there. From a products standpoint, virtually all manufacturers are also using CAD-CAM so it would be a simple matter to change the CAD to cut, as desired. Really not that big an issue, other than afraid of the "unknown" factor. I would though miss going to the lumber yard and sorting through the 23/32 plywood as my tape measure, given an electron-microscope is toted around with me, is easily determined. It is so simple as is. 

 

Come on, even our nominal lumber is "called" wrong these days. 2x4, etc. has not been a 2x4 for a very long time. Didn't hear about too many issues when they lost that half inch all the way around.  

Link to comment
Share on other sites

Joe,

 

I was unaware that it was incremental, as aside from the nominal dimensions of today, I have frequently found the old 2x4's in renovations. Can't recall much in-between, but can recall the 2x? were closer to __ 5/8", so make sense.  

 

It could be worse though, as we could be using barleycorns and rods, whereas a 2x4 would be a 6x12 barleycorn, nominally 4.5x10.5 barleycorns? Is that right? Not too fluent in my barleycorns. I blame all of this on the British, to which Glenn is a descendant of, thus this is all Glenn's fault. :) 

Link to comment
Share on other sites

Keith,

 

I'm also a descendant of the British.  My ancestry goes back to the Rhode Island Colony in 1626.  ;)

 

IAE, the 2x_ was originally 2" rough cut lumber

 

Then at some point in time (early 1900's I think) they started planing them to make them smooth so that splinters were less likely.  Hence the 1-3/4" size.

 

About 1950-1960 they reduced it to 1-5/8".  I'm not sure exactly how that came about but I believe it was about shrinkage as the lumber was dried after milling.

 

In the 1960-1970 time frame they reduced it to 1-1/2" - probably just to save material (more yield per log).

Link to comment
Share on other sites

Interesting Joe, and was not aware, and really had not thought about it much. One thing for sure, the overall quality has gone down hill. I find old actual rough sawn 2x4's still in great shape. Some in the hundred year old ball park.

Link to comment
Share on other sites

Fyi: Here is a link to the current lumber size rules for the WCLIB which was the certification authority I used when I was certified to grade lumber back in the late 80's and 90's

 

http://www.wclib.org/r17-pdf-online/wclib/pdfs/l_WCLIB_2004_RulesBook_9.pdf

 

Note the green vs. dry surface sizes as well as the Standard Sawn (Rough Green) sizes.

Link to comment
Share on other sites

This really points out why dimensions from floor to floor can't be relied on when using Lumber for Floor Joists.  Green vs Dry can be 1/4" different.

 

But if you think that's bad - Log Construction typically must allow for at least 2" shrinkage per Story/Floor and the Door and Window Openings need to allow for a minimum 1-1/2" shrinkage.

Link to comment
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
 Share