Simple span table

[John Raabe]

Here is a recent span table from JLC.



This from: http://www.jlconline.com/jlcupdate/2010/1008/1008fg.html

[MountainDon]

Comparing 2x10 between the above chart and the AWC calculator confirms the Canadian lumber better ratings.

In the AWC calculator the Canadian lumber is designated by
north' as in SPF (north), Doug Fir- Larch (north), Hem-Fir (north)

I guess by definition, there's not much SYP in Canada.  

[John Raabe]

Those northern guys can grow sturdier trees!

While the charts don't show the select structural grade, I notice a number 1 SYP can also work for the 20' wide cottages (at 16" centers, almost any 2x12 will work at 12" o/c).

[MountainDon]

Those northern guys can grow sturdier trees!

I wonder if that is because the growth is slower, the yearly rings narrower, because of the cold and longer winter?

If so my sloooow growing ponderosa's and firs ought to be stiffer than lower elevations. 

[Don_P]

tread carefully, or at least lightly, with that logic 
Density and percentage of latewood are better strength indicators in softwoods, not rings per inch... and in hardwoods it gets real counterintuitive. Ring porous woods like oaks, hickories, etc are actually stronger if faster grown.

Came out of the woods after dark this evening, walked with some foresters through a grove of 3-400 year old white oak, talk about tight rings  .

[MountainDon]

Interesting to know it's a bit of a mystery.     Not to worry. None of the trees I would cut are big enough for much. The ones that are big enough for beams and good size planks are simply too beautiful to be cut for timber. When it takes 90 years to get a nine inch tree you can imagine how old the few 20 to 24 inchers we have must be.

[Don_P]

Wow that is slow growth. There are lots of variables is probably the most mysterious thing.

We visited 2 other stands this evening, both white pines. The first was some of the tallest white pines I had seen. They were planted 70 years ago on a very tight (by modern standards) spacing of about 3x3'. The trees really had to stretch for daylight and has made relatively small diameter but very tall pines. They are about 120' tall by 16" diameter, tight rings. Wind got into the stand about 3 weeks ago and tore a swath. They are tall enough and spindly enough that the entire stand needs to be clearcut before they all windthrow.

The second white pine stand was planted about 50 years ago, has approximately equal volume but was stocked at about half the rate of the tall trees. It had been thinned 3 years ago to help regenerate some seedlings in the understory. It suffered zero loss in the wind even with some pockets for the wind to grab. Shorter, stouter, wider ringed trees.

What I loosely quoted in my previous post is from forestry texts, Peter Koch has probably done the most writing and research on it. Basically from about 6-40 rings per inch pines should be judged more by percentage of latewood than anything else. You can have a tight ringed or a open grained piece with roughly equal percentages of dense latewood...or you can have a very tight ringed stick that has paper thin latewood and is "unusually light", a polite term for #3.