On Sep 3, 8:16 am, dpb wrote:
DanG wrote:
Bob,

I see this so often, an old place with 2x4 rafters spanning 12' or
more . Many times there are 2 and 3 roof layers and the rafters
are not noticeably bowed, stressed, or broken. The roof tends to
feel rock solid when walking on top.

These things can't make current code, yet they stand just fine.
Are codes over built? Was the old lumber that much better?

...

Some of both...

Much of older lumber was "old forest" growth which is typically tighter
grain that the "plantation grown" present construction lumber. Also, if
it is roughly 50s or earlier, dimension lumber was somewhat larger in
cross section (the 1-5/8 finished vs 1-1/2 for 2x stuff) and if it was
earlier even larger or occasionally roughsawn was nearly full dimension.

--

You are also much more likely to see doug fir 2x in old houses--
something you rarely see except in 2x10's and 12's in lumberyards
where I live these days. Most 2x4's I see are spf (spruce-pine-fir).
I was looking at a unit of 2x4's the other day where every single one
had at least part of the pith of the tree--meaning that they are
cutting them out of very small trees. I don't think they are
necessarily second growth trees, because the growth rings are pretty
tight. A lot of spruce, jackpine, and true fir from canada. 50 years
ago, I think that noone in their right mind would have dreamed of
making framing lumber out of those kind of trees.

At any rate, I think carpenters were also much more likely to push the
envelope in the old days--sometimes it worked, and sometimes it
didn't--look how many old roofs sag. I'll bet you our modern roof
framing is going to last a long time, if moisture doesn't get it
first. I'm working on a 90 year old house at the moment, and the old
saw "they don't make them like they used to" isn't always true.