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Author Topic: Starting to build the solar kiln  (Read 221 times)

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Offline btulloh

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Starting to build the solar kiln
« on: May 31, 2017, 05:14:28 pm »
I can't get the list whittled down to where the solar kiln is at the top, so I'm getting starting anyway.  DanG the torpedoes! Full speed ahead!

It seems like some of this has been covered more than once, but I can't find it searching the forum, so I'm gonna ask:

- Is OSB ok to skin inside?  Someone said it won't hold up in the heat, but that didn't seem to be the consensus.  Would CDX work better?

- Same question for flooring.  OSB, CDX? Skin under the joists with CDX or is PT plywood a must?

- I'm planning to do lap siding on the outside and no sheathing, but put tyvek wrap under the siding.  OK?  Not Ok? 

- I'll be using fiberglass bat for both walls and floor insulation.

This thing is going to be 12'x5' inside.  That should be an appropriate size for now.  I'm trying to keep the costs down, but I don't want to compromise the function too much.  Thanks in advance for any input.

BT



HM126

Offline ChugiakTinkerer

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Re: Starting to build the solar kiln
« Reply #1 on: May 31, 2017, 06:20:27 pm »
The VT design document recommends plywood such as CDX for the flooring, but only specs PT for the floor joists and blocking.  I doubt there would be any difference between OSB and plywood for sheathing at the anticipated temperatures.  I did find a study that compares the strengths of both after prolonged exposure to heat (ie a house fire) and OSB fares slightly better (see here).  Figure 4 shows the strength vs temp curve.  Of course the material used in that study may not be the same as you can buy today.  I'd probably go with OSB and make sure to coat it well with the rubberized paint.
Woodland Mills HM130

Offline Tree Dan

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Re: Starting to build the solar kiln
« Reply #2 on: May 31, 2017, 06:52:39 pm »
I used OSB on the inside, and its working just fine.
I would go wider than 5' though...If your stack is 4' wide i would build it min. 6'wide inside.
Have fun with the build!
Wood Mizer LT40HD, Kubota KX71, New Holland LS150, Case TR270
6400 John Deere/with loader,General 20" planer, Stihl 880, Stihl 361, Dolmar 460, Husqvarna 50  and a few shovels,
60" and 30" Log Rite cant hooks, 2 home built Tree Spades, Homemade log splitter

Offline btulloh

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Re: Starting to build the solar kiln
« Reply #3 on: May 31, 2017, 08:23:45 pm »
Thanks for the reply.  OSB would certainly be cheaper as long as the glue doesn't fail, the plywood probably uses the same glue, so . . .

I may decide to go wider than five feet, because it doesn't add much material and gives me more flexibility.  I use 32" packs mostly, because it works for me and my equipment and I'm low volume.  Wider still sounds better though and gives me some future options. 

Generally I will be drying stuff that's 8'6 or 10'6 so that's where I came up with the 12 foot length for the kiln.  I have a tendency to over-do the while-your-at-it's on my plans, and that can lead me to building something the size of a gymnasium if I'm not careful.  (While I'm at it, why not make it big enough for 16' lumber?  Gosh, 20' might be nice sometime.  Maybe I should go for 1500 bd ft?)  So that's how it goes.  Just trying to keep this smaller for now.

Thanks. And keep 'em coming.
HM126

Offline jaciausa

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Re: Starting to build the solar kiln
« Reply #4 on: May 31, 2017, 09:59:35 pm »
I believe pressure treated cdx was used in the Virginia Tech Kiln Plans. Moisture is not good on OSB over a period of time.

Offline GeneWengert-WoodDoc

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Re: Starting to build the solar kiln
« Reply #5 on: June 01, 2017, 06:51:17 am »
Use CD-x if possible.  No need to use pressure treated sheet goods.  The plastic goes on the inside with the insulation being to the outside of the plastic.  Keeps the moisture inside from getting into the walls.  OSB will work ok but might not last as long.  The bottom of the joists can use hardware cloth to hold the insulation and keep most critters out.  Ventilate under the kiln and then PT plywood or framing is not required.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Offline btulloh

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Re: Starting to build the solar kiln
« Reply #6 on: June 01, 2017, 07:01:58 am »
Thanks Gene.  Good info.

I'll be keeping an eye out for upcoming classes in my neck of the woods.  (Mid-Atlantic)
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Offline Tree Dan

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Re: Starting to build the solar kiln
« Reply #7 on: June 01, 2017, 07:48:02 pm »
For some reason i thought we were talking about the inside interior walls.
Thats where i used the OSB.
There is normaly a marking showing the Outside of the sheet, i would keep that side facing in.
As for the exterior walls I used RS pine - 1x8 , if i ever build another solar kiln I would use plywood with good paint.
Have fun with the build!
Wood Mizer LT40HD, Kubota KX71, New Holland LS150, Case TR270
6400 John Deere/with loader,General 20" planer, Stihl 880, Stihl 361, Dolmar 460, Husqvarna 50  and a few shovels,
60" and 30" Log Rite cant hooks, 2 home built Tree Spades, Homemade log splitter

Offline btulloh

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Re: Starting to build the solar kiln
« Reply #8 on: June 01, 2017, 08:13:18 pm »
Definitely talking about the inside walls.  Sounds like cdx is a better choice for inside.  Easier to paint too, although I'm hoping to find a way to spray whatever I put on the inside.  Planning to use SYP lap siding on the exterior.
HM126