Soft Maple lumber

[Faron]

I have to rebuild my sawmill building.  The replacement will be a pole barn structure. I expect my supply of yellow poplar won't do the complete job.  I have a fair amount of soft maple still on the stump.  Does anyone know a reason not to use it for nailers and purlins?  I've used some in the past, and it seems to be as strong as poplar, and holds nails well.

[Ron Wenrich]

Everything I've seen on the mechanicanl properties shows that red maple is a little stronger than yellow poplar.  I wouldn't see why it isn't a good alternative.

Pennsylvania is putting a push on using red maple as an alternative to other woods for construction.  The new forest resources building at Penn State is using laminated red maple beams in the construction.  They are also using it for bridge deckings in the state parks.

[beenthere]

Red maple is in the 'soft' maple group, and difficult to separate out unless the tree is identified before processing. There are other soft maples in that group that are not as strong as the red maple, and not as strong as the yellow poplar, I believe. In the north (northeast and northern WI, etc), there is more red maple found. Not sure what is found in the soft maple group in Indiana - silver maple?. Still I'd think soft maple could be used for nailers, but be careful with it as purlins, IMO. Even regular stud grade can be a lousy purlin.

[Faron]

Thanks, guys.  We have red and silver maple here as well.  I think what I have to cut is red maple, but I better double check, as it has been a while since I saw them.  Most soft maple here goes whnd, so using it in my building makes sense economically.  I'm going to use 2 x 8 trusses on 6 foot centers. I aim for this roof to stay put.

[Furby]

Are those prebuilt trusses???
What's the span and pitch???

[Faron]

Furby, As of right now, we intend to build the trusses.  45 or 48 foot span, and figuring on a 4-12 pitch.  We used to build lots of pole barn trusses, back when I carpentered.  We toenail them together, then glue and nail plywood plates on the joints.  Technically, they don't have the engineering stamp of approval, but are stronger than the enginered ones with the metal cleats.  When I built my addition, the expert from that other site told me the powers that be would NEVER let me build my own trusses.  I'm sitting under them now typing this. ;D ;D

[Furby]

That's cool!
6' just kinda sounds a bit much for the spacing, that's why I asked.
Ya doing a metal roof?

[Faron]

Furby, Yep, metal roof probably with insulation under it.  By a bit much, do you mean too close or far apart?

[Larry]

Faron,
Call that whnd maple by a different name and ya might find a buyer or two. ;D  Saw one on the hunt down in the wanted section week ago but think he found a supplier.

[Faron]

Those worm holes ARE kind of attractive, aren't they?  Really they ought to command a little premium. :D

[Larry]

If you want to keep any you better hide it in your attic so that dang Curly Woods guy won't find out about it. :D :D :D

And yes I find it quite attractive.

[Furby]

Well I was thinking to far apart.
I tend to overbuild things a little. :
With metal roofing, 6' may indeed be fine, never done it so I won't judge it. For shingles, it would be to far due to the increased weight and cost of needing much heavier roof sheathing.

I try to stay open to new ideas, but when people start talking about roofs.....................I tend to be cautious, ya gotta remember the "possible" snow load, and wind load. Roofs add a tremendous amount of strength and stability to a building.

[Faron]

Furby, Indeed we would decrease the spacing if we were putting a shingle roof up.  Our crew always used 2 x 4 trusses on 16" spacing on houses.  Some builders used 2' spacing, but we considered those poorly built, unless they used heavier plywood than normal.  
Most post buildings in our area have trusses on about 7 1/2' spacing.  The 2x4 purlins on those are nailed on edge with pole barn nails.  By pulling in to 6' spacing, we will be able to put the purlins down flat.  I wonder if you guys in the frozen north have to build stronger due to increased snow?
The building that collapsed was kind of a unique building.  It was built in the early 50's for the farm equipment side of an automobile dealership.  They built trusses and poles out of 7/8" and 1" oilfield suck rod.  The purlins were 2x6 oak. It was an open sided building. until we put two sides on one end .  Found we couldn't stand the wind blowing through there. ;) The only problem was they put poles and trusses on 13' centers.  When the late departed storm dumped about 3' of snow on the roof, that was all she wrote.  I knew the trusses were awfully far apart, but since it had been there 50 years already, I figured it had already been tested.  That's what I get for figuring.

[Furby]

Just off the top of my head I don't belive there is that much difference in our requirements. The difference comes in the fact that we get the snow load every year, sometimes for weeks at a time. You guys don't get it as offten. I think that's why a lot of people overlook the "possible" snow load part, it just don't happen as offten.

We use standard factory prebuilt trusses on 2' centers, per manufacture's instructions. Some people go ahead and put them 16" o.c. anyways.Can't blame them for that.
Every situation is different and sometimes 2' don't work when the roof structure has been modified beyond the design specs. It happens.
A big thing I've seen a lot of is people using 2x4 or 2x6 rafters over long spans. They don't realize that rafter s totally different then a truss, and there can be some big problems there.

May I ask what the posts were made of on the building that you are replacing, and their size?

[Faron]

Weeeeell, Furby, don't laugh, but the poles were four 1" suck rods spaced about 12" square and tied together every 16" or so.  They resembled a four legged home tv tower, and lots of people thought that was what they were.  When the trusses gave way,some of the "poles" bent over.  I always figured wind would be the demise of the building, not snow.

[Furby]

Yep, open walled buildings are VERY easily taken down with wind if not correctly built!

I would guess, and this is just a guess, that the posts are what actually failed first.
Without the strength of walls or wall sheathing, and even in some cases with that strength, the roof load including the snow load in this case, causes the structure to twist and flex.
The posts were probly more then enough (although the spacing sounds a bit much), for a straight on, downward load.
Take some 6"x1/4" square sticks, or something close. Stand them on end on a board or piece of cardboard with a little hot glue. Then lay a piece of stiff cardboard on top. Gently place your finger on it and try and make it move a little. Now if you were to brace your little structure with a couple of books or boxes, you can add a fair amount of weight. Carefully pull the books away, and add some more weight or wind, IF it's still standing. While not exactly the same as in a building, the general idea is there. Adding braces helps, as does adding wall sheathing. It makes the whole building much more stable. The materials use do play a big part in all this. Steel posts, with steel trusses welded together with some braces, will take less to strengthen then wood held together with nails and glue.
The added snow load, simply gave enough weight to allow the building to shift enough to overcome the strength of the posts.

Now if all your posts are still standing and the trusses simply spilt and fell inward, it was simply truss failure.
Did it all fall toward the middle, or is it off to one side or corner?

[Faron]

This puppy buckled down about 12' in on the east side.  Looked like a giant had karate chopped the roof right over my saw.  The south gable pulled north, north gable went south, the eastern poles nearest the point of failure bent west.  I've got pictures, but so far haven't been smart enough to get them posted.

[Furby]

Sounds like truss failure after all.

Uploading pics is easy. There are some really good instructions on the upload page, but if ya still need some help........toss me an IM, I'll walk ya through it!

[Don P]

On soft maple being useable for lumber;
The Forest Products Labs has done some research and the results were quite good from everything I read. They have made and tested glu-lam beams and trusses. I talked to one of the technicians at the Logging Congress a few years ago who worked on that research . He said that normally when they stress test a spf truss the failure is when the gang nail plates pull out of the wood. With red maple the failure was when the gang nail plates tore in half  .

Here's their techline on that research;
http://www.fpl.fs.fed.us/documnts/techline/vi-16.pdf

There's quite a bit of research on maple for structural uses over there.

[Faron]

Thanks for the info, Don P and everybody else!  Looks like my sow's ear might have a little silk purse in it after all! 8)

[devo]

Can wormy soft maple be used in load bearing parts?

[Don P]

Hmm,
I guess that would depend on grade, A quick read of the Nelma rules I only saw "limited pin holes"
http://www.nelma.org/graderule.asp
I have certainly gotten structural wood on the job that had been ambrosia chewed...but I couldn't say it was supposed to have gotten thru. It would all depend on degree, I have plenty that has just a few holes and would have no problem using. There's some in our bathroom cabinets that was just too wormy and pretty to go for framing.

On a kind of related topic, our local state delegate is interested in the trouble we are having getting locally produced structural lumber graded. He has responded to a letter where I requested that they consider offering grader training at the community college level for small time producers...off the soapbox

[Furby]

That's a pretty good idea Don!
Thanks, you may have just made it a bit easier for the rest of us. ;)