Fresh sawed cottonwood

D6c · February 09, 2018, 03:46:48 PM

Can I get away with sawing some 2x4 lumber out of cottonwood and use it right away to build the walls of my solar kiln?
If I put sheeting on I would expect to get mold growth on the cottonwood, but if I left the sheeting off for a while for air drying could it work? (I'm probably going to build it inside my shop on skids)

Would you saw the 2x4's oversize to allow for shrinkage?....and how much?

...or would I be better of just going to the big-box store and buying lumber?

GeneWengert-WoodDoc · February 10, 2018, 11:13:09 AM

You can use the wood immediately, but because of variations in shrinkage after drying, you will likely have wavy walls, if someone looks critically at what you have. No need to increase thickness as the framing does not matter about thickness, but width should be the same and perhaps 4.00". Another concern with wet is that the nails will pop out and you also will loose strength of the fasteners. If you can air dry for 30 days, that would be better...45 warm days is even better. Then resize them to uniform width (saw or planer).

brianJ · February 10, 2018, 02:48:00 PM

Fasteners...Well if you can't wait to dry and would rather say be fast(eners) screws be better than nails. They dont pull out so easy with a wee bit of shrinkage.

GeneWengert-WoodDoc · February 11, 2018, 06:50:09 AM

When using a nail, staple, screw in wet wood that then dries, as the fibers shrink maybe 6%, they will tear around the fastener and you will lose substantial strength. In a dry piece of wood, lots of the fibers are pushed aside, compressed and give high strength.

Deere80 · February 20, 2018, 03:48:44 PM

I have used a lot of cottonwood for building projects but I just cut my thickness that I want say 2" and leave it random width what ever I can get out of the log then stack for a month to dry. Then when I'm ready to build put back on mill take a clean up cut to take any crown out of them and cut your 4" or 6" whatever you want. Works alright but a lot of times the cottonwood likes to twist.

Darrel · February 22, 2018, 07:27:53 PM

I cut some cottonwood lap siding once and put it up a week later and it twisted something aweful. I also cut some 8/4 cottonwood slabs that did everything but stay flat. That was 2 years ago. So I left it to rot but it didn't. It flattened back out.