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Cotonwood as Posts and Timbers

Started by clif, December 26, 2007, 10:19:41 PM

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clif

I have a friend who has several large (28") Cottonwood trees that we bored to see if and how much center rot there is and it appears it is minimal and only very close to the center of the tree if any.  My question is if I were to saw 8-10" timbers/posts and not box the heart/rot would they be fairly dimensionally stable  as they dried in place or would I have a "can of worms"  so to speak?  I am adding a 20'x24' TF livingroom/artic entry to an existing building and I really like the looks of cottonwood.  Clif
Mighty Myte Mark IV Band Saw Mill .  " Don't let the past hold you back"

BandsawWarrior

Sometimes what we do is cut timbers one to two inches oversize, sticker them, forget about them, and then resaw them after a hot summer.  We're produced some of our nicest wood this way.  Now I've never tried it with Cottenwood, but if you have time maybe it's worth a try. 

 

 
Tyler Hart
T&N Custom Sawmill

iffy

This is second-hand info, but a local sawyer says when local farmers want to build a pole barn and bring him cottonwood to make the dimension lumber out of, he waits to saw it until they have the poles in the ground and are ready for it. He claims if he cuts it any earlier, it will try to tie itself in a knot. He tells his customers to take it home and nail it up immediately, and it will dry straight enough for a pole barn. A lot of old barns in the area are built with cottonwood, and old timers say after it gets completely dry it turns really hard. Don't know any of this for a fact, just repeating what I've heard.
Can put you in touch with a local guy who milled square beams and built a dovetail log home. He hasn't mentioned any problems with excess warpage, but I think he stacked it green.

Gary_C

Cottonwood logs start to rot before they hit the ground. Overall very poor rot resistance.

It will stink when you saw it and will stink any time it is rewetted after drying.

If you keep the heart centered in the boards or timbers and sticker it immediately after sawing, warpage is not that big a problem. However some boards will warp no matter what you do.

It has very poor nail holding abilities. Reason is because it is very prone to collapse in the wood around the nail or bolt and then the nail will fall out or the hole will enlarge around a bolt. That problem is especially bad where the wood is subject to wide temperature variations and the resulting condensation on metal parts.

So cottonwood needs to be dry before using. Do not use it anywhere next to the ground and only use it for non structural uses. I would not use it anywhere it could not be easily replaced or use it only for short life applications.

Other than that, it will work good.   ;D ;D
Never take life seriously. Nobody gets out alive anyway.

Justin L

I can't say about the timbers, but I have 500' of 4/4 Cottonwood kiln dried & still on sticks. from what I can see, it looks OK with minimal warping. I'm going to plane it & finish the inside of my kiln office with it. If it's good enough for a pole barn, it's good enough for my office :) It is a pole barn, actually...
I know you believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant! :)

JGroebner

I personally would NEVER use cottonwood for Anything structural.  It's light, not very dense and therefore WEAK.  Bugs LOVE it because it's easy chewing.  It has a lot of the same properties of drift wood.

Jared

Furby

Driftwood can be most any kind of wood, and is not a species. ;)

clif

Not looking very good for the cottonwod is it?  I was thinking that cottonwood had similar strength properties as spruce.  I guess I will look it up again, although  I don't remember where I found it last time.  O well, back to the drawing board.
Mighty Myte Mark IV Band Saw Mill .  " Don't let the past hold you back"

beenthere

You can find clear-wood strength values in the Wood Handbook, and get an idea what the relative differences are between species, assuming the quality of the beams/posts are similar.

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm

Go to Chapter 4
Cottonwood is about 10% lower than Sitka spruce...but may yield higher quality.

Have no idea what driftwood properties are... ::) ::) ??? ??? :)

south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Thehardway

The properties of driftwood are as follows:

Strong enough to bust your bottom unit or prop.
Burns well in beach fires, good for hot dog roasting an d marshmallow toasting
Holds sand and gravel well
Difficult to finish and machine, with a tendency to splinter
Dulls tools quickly

Range is widespread along coastal areas
Availability is good especially after storms, flooding or hurricanes

Uses:

Popular for landscape, yard and wall decoration
burled peices can sometimes be turned into bowls

Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

submarinesailor

Hey Hardhead... OH, I mean HardWay – is this saltwater or fresh water drift wood??? ;D ;D ;D :D :D

Furby

Yep, those are two different species aren't they Sailor. ;)

Jim_Rogers

Check out my new post about driftwood......
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

HOOF-ER

I asked a relative of mine about cottonwood and building with. He said come here want to show you something. Took me to the basement pointed at the floor joists in his house and said that they were all cottonwood. What I know is keep it  DRY. Rots quickly when wet. Doesn't hold a nail as well as other woods. Crappy studs from the lumber yard don't hold a nail well either!  ;D   IMHO cottonwood would be as good nailing as that stuff they call pine studs.
Home built swing mill, 27hp Kawasaki

JGroebner

WoW I didn't think a reference to driftwood wood be so "colorful".  Our neighbors to the west in S.D. are plagued with cottonwood, it's light, it's molecules when viewed through a microscope almost seem misplaced.  It's like driftwood because it's brittle, it's light, it's lost it's identity ;D

Jared

tsodak

I don't know, may be in the process of learning a hard lesson, but no sign of it yet.

The one wood we have in mass quantities is cottonwood here in SD. I asked many of the same questions a year ago, and got just as variable of answers, so I just did it. 

Cut posts 8x8 and 6x6, happy with both. The building I am using them in has no floor, so generally easy to replace if they rot off, I put them wrapped in plastic into very sandy dry solid and built a 12x36  lean to barn out of 100% cottonwood. Rafters, purlins, board and batten siding, trim, everything. I am almost finished with the siding, but need to put the battens on. All in all it was the funnest building project I have ever had.  I thought it worked well, and I will treat it with spray on sealer or more likely just used oil mix sprayed on. It does have a steel roof, so every piece that is exposed to weather is vertical. I figure worst case if the posts rot off, I can dig and pour a concrete base to bolt the pole to, and if the walls don't last I can always pop it off and put steel on the walls.

I am happy enough that I am making plans and gathering logs to move on to the 40X40 stick framed garage and shop I  have always wanted. Plan to start digging footings in June. Going to mainly saw it as I build it. But will precut, sticker and stack a bunch of 2x6's for the walls in the spring. I just overbuild it all. If I could get by with a 2x4 I use a full dimension 2x6. Size everything up.

Go for it.

Tom

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