20 Foot 2 X 12's

[Greg Cook]

Hey Y'all!   Once again seeking to take a "dipper-full" from the pool of knowledge here.

I'm sawing poplar for my barn, and just starting on some 20 foot logs for long 2X12's . As I squared up the 3rd side, it occurred to me I might gain some strength by leaving the "live edge" on that 4th side.  I will have to notch the ends, leaving a 12" wide tail to sit across my beams, so that the tops are uniform for the floor of the loft. That would leave the rest of the joist 14" to 18" deep. 

My questions:
1. Will notching the ends to 2X12 dimensions void the strength I'm hoping to gain by leaving the added wood in the middle?

2. How will this affect the drying (air drying)? Will I have more pronounced bow from leaving this edge? Maybe less?  Which way would it tend to bow? Toward the bark edge or sawn edge?  (Toward the sawn edge would be ok, since that side would be crowned up.)

3. Would leaving the sapwood cause me problems, like insects, which would have been sawn away? I am peeling the bark off the logs before I start to saw them, so it won't cause problems.

4. Any other things you can think of?

   While leaving the edge would save a little time, I'm mostly looking at the added strength, if any.  This is such a long span, I want all I can get.  Your opinions are most appreciated.

Thanks,
Greg

[Tom]

my opinion:

1= no

2= sawn lumber generally moves toward the bark. (not always, it may depend on the bow in the tree.) The bark side will usually be crowned.

3= Not so much, but the bark would.  Generally sapwood is more affected by insects but the bark and sweet cambium actually attracts them.  The heartwood is naturally more rot resistant than sapwood.

4= The added inches of wood in the timber will add beam strength, but diminishes clearance and may be difficult to add to later.  Other than that, it's just more wood.

[thedeeredude]

As far as I know(not a lot ;D), leaving the natural edge increases strength because the grain cant run out.  Like a riven piece of wood is stronger than a sawn piece of wood.  The barn at work has beams for the 2nd floor that are hewn only on the side that the second floor lays on.  The other potential 3 sides were stripped of bark and left natural.  The only interruption is support posts which were notched into the beams.

[solidwoods]

If your worried about exceeding span limits, check a carpentry span table and see if your design is within span/weight limits.
jim

[bandmiller2]

Greg, it depends if you want the rustic look.I don't think the little stregnth you will gain is worth the probible insect invasion,and problems if you ever decide to do something with the celing.Notching the ends is fine I would avoid sharp corners and round the transition points.Frank C.

[Greg Cook]

After I went to bed last night, I must have been sawin' some logs, 'cause I woke up with the thought that I could just saw these logs through-and-through, leaving the live edge on BOTH sides until they've dried somewhat.  Putting them back on the mill to edge later will be a pain, but hopefully I can gain a little strength.  The span tables show that I'm OK on the span rating for poplar, but not by much.  I want all I can get. I am sawing them a full 2x12, which I don't think the tables take into consideration.  I can also decrease my spacing, but good clear logs this long were tough to come by (read COSTLY) in my area. 

Thanks for the input so far....

Greg

PS to Jim: I'm probably sending you some blades before long, if you aren't covered up with sharpening.

[Fla._Deadheader]

If you saw the logs through and through, some of the lumber will be quarter sawn, and that would not be the strongest grain orientation for rafters. I would think turning the logs to get the best grain orientation would be better ???

  Also, when you cut the notch, that will be the weakest or actually, the strongest place in the rafters, ESPECIALLY if quarter sawn by sawing straight through the logs. The grain could start to separate by cutting the notch, and not having grain running across the header plate.

[backwoods sawyer]

Leaving a live edge will not weaken your joist, and taking the bark off will leave you with a board that will not increase your bug issue. Notching them at 12" will not weaken them beyond a normal 12" as long as you do not cut deeper then the notch on the cross grain. You will gain minimal strength, and loose a flat surface.

When my customers need more strength, they start with the strongest local species (Doug-fir) and sort out top quality logs to use. Cut thicker then needed 2"-2 ½" and place them closer together. 16" max spacing, 12" and even 8" spacing for heavy loads.

Just be sure that the rest of the supports can handle the load as well and that the weight is transferred down thru the wood, rather then relying on light duty joist hangers. (Put headers on top of the posts, rather then mounting to the side of the posts)

[mike_van]

Greg, if your 2x12's are just making the span, cut 2x14's if you can ?  Just me, but I wouldn't leave the live edge - You may find someday you want to put a ceiling in for??  whatever reason - They'd be a real bugger to snap lines on & rip after they're installed -

[Greg Cook]

Thanks Guys!

I already thought about the future ceiling issue, but that would only happen in the shop area, and I could do a grid ceiling and transfer a good bit of the wieght to the walls, plus it's lighter than drywall.

There are no Fir in this area, and large pines are about 80 miles away, and not cheap to haul.  My poplars are 20" diameter and up (small end), so once I choose an opening face, that's how the rest of the boards are oriented. I'm being VERY cautious on that first-cut decision! Most of the logs are good and clear, some will have a few knots/spikes. What can't be trimmed away will go in the top edge. There will have to be some of them quartersawn, the ones boxing the heart. I'm sawing those thicker (3X12 min.) to help compensate for the grain orientation.  I'm also saving the boards that are almost 12 inches wide, just to have some to double up if needed. 

I am leaving both edges on for now, to help them dry a little straighter (I hope :-\  )  I do have two logs that have a lot of sweep (almost 4" in the middle). I know all of that 4" isn't sweep, some is the taper, but not much. I think when installation time comes, I'll notch those, with the crown up of course, and let them settle for a while before chalking a line for the top edge and hewing it flat on top.  Well, not flat, but with a little crown to match the surrounding joists.

I thought standing up those 25 foot poles by myself was bad enough, but these green boards are HEAVY.  Think I need a set of forks...  :

Greg