Greenhouse wall - How to avoid rot

Eleven years ago, I built a greenhouse with a 2' high pony wall. That wall is "L"-shaped, 36 feet long on one side and 18' on the other. The wall was framed with 2X4 rough cedar. On the inside is poly (polyethylene, not urethane) (visqueen, Keith) and 1/2" plywood. Fiberglass insulation between the studs, and 1/2" plywood sheathing on the outside. The sheathing is (was) covered with 2" expanded (white bead) Styrofoam, and with cement board (i.e. the modern equivalent to asbestos board). The top 12" had vertical cedar siding and the bottom was dirt, as there is a 32" wide irrigated raised garden bed on the *outside*. (Inside greenhouse beds are plywood boxes, so dirt does not touch the wall there.)
So, I recently had all the dirt removed in the raised bed so I could check out the condition of the wall. Removed the siding and the Styrofoam (the cement board had practically disintegrated). The plywood sheathing had considerable rot. The wall framing is in pretty good shape, the sills have no rot that I can detect, and only three of the studs have rot on them. The interior plywood sheathing looks like it's got rot in quite a few places, i.e. it looks black behind the polythene. But I'll fix that once I've solved the problem I'm asking for your ideas on; namely:
What do I do now? Bear in mind that one side (inside greenhouse) is hot and damp, and the other side is cool and wet (dirt in raised bed). Things I have thought of:
Use galvanized sheet metal as sheathing (this would isolate the wall from the dirt). Pour concrete between the studs (hard to do & I would lose the insulation value which is important as we start using the greenhouse in March, which is still winter here in the Yukon) Remove the raised bed (Not acceptable to the LOML - she'd rather dig out the bed every ten years)
What would you do? Any brilliant ideas?
Luigi Replace "no" with "yk" twice in reply address for real email address
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Thu, Jul 24, 2003, 11:00pm (EDT-3) snipped-for-privacy@nonet.no.ca (LuigiZanasi) was allowed a crayon and scrawled: <snip> What would you do? Right now, I'm thinking seriously about making a cup of green tea, and a sandwich. Oh, I suppose you mean in your case. OK, YOU have a sandwich and a cup of tea too.
Any brilliant ideas?
Loads of them. However, about your problem, no. LOL
But, GitRot might be a viabe solution. Not tried it yet myself, but have heard good reports. That was the first thing that came to mind, and the only thing that seems appropriate, unless you want to replace everything.
Whoops, on the other hand, maybe not. Says here the wood is supposed to be dry. http://www.starmarinedepot.com/detail.asp?product_id=BL8024&p=Boat+Life+Git-Rot +
Somewhere tho, I have read about a similar treatment, that can be used on damp wood (probably not wet). Can't remember just where, but might have something stuck away somewhere. I'll only charge half rate for looking, and a small additional fee if I find it. Then just another small fee to let you know what it is. LMAO
JOAT Always put off until tomorrow something which, tomorrow, you could put off until, let's say, next year. - Lady Myria LeJean.
Life just ain't life without good music. - JOAT Web Page Update 23 Jul 2003. Some tunes I like. http://community-2.webtv.net/Jakofalltrades/JOATorJackOfAll/page4.html
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Thu, Jul 24, 2003, 11:00pm (EDT-3) snipped-for-privacy@nonet.no.ca (LuigiZanasi) found out they still won't trust him with anything sharper than a wooden spoon (there's your wood connection - LOL):
OK, found it. You can send a small sacrifice for the Woodworking Gods, that will cover it. I didn't read it all, but does have something on wet wood. http://home.att.net/~DaveCarnell/rot.html
JOAT Always put off until tomorrow something which, tomorrow, you could put off until, let's say, next year. - Lady Myria LeJean.
Life just ain't life without good music. - JOAT Web Page Update 23 Jul 2003. Some tunes I like. http://community-2.webtv.net/Jakofalltrades/JOATorJackOfAll/page4.html
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On 25 Jul 2003 07:18:25 -0700, snipped-for-privacy@mc.duke.edu (tim collins) responded:

I refuse to have Chromated Copper Arsenate anywhere near my food. When I worked for the Yukon Housing Corporation in the late 80s and early 90s, I argued against using PWF (Preserved Wood Foundations). Everybody thought it was just a function of my non-ethnic background (FYI, IGWOS ethnic is anyone or anything that is not Italian, of course - You all know how to stop an Italian wedding, right?) Now things are coming to roost, with your EPA banning the stuff and a subsequent ban likely in Kanuckistan also. I digress.
Problem with vents is that it would considerably reduce the insulation value of the wall - I start up the greenhouse in March when temperatures can go to -20 Celsius.

Now, cinder blocks is an idea. I need to figure it out a little more (e.g. foundation, etc.)
Luigi Replace "no" with "yk" twice in reply address for real email address
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Sat, Jul 26, 2003, 9:43am (EDT-3) snipped-for-privacy@nonet.no.ca (LuigiZanasi) quizzes the group with: <snip> You all know how to stop an Italian wedding, right?) <snip> Tell the groom the bride's not really pregnant.
Tell the groom he's not the father.
Tell the groom the bride's going to stop working afte the wedding.
Tell the groom he's going to have to get a job after the wedding.
Tell the groom the gun's not really loaded.
All tried and true answers. Change to fit appropriate ethnic/regional group as required.
JOAT Always put off until tomorrow something which, tomorrow, you could put off until, let's say, next year. - Lady Myria LeJean.
Life just ain't life without good music. - JOAT Web Page Update 23 Jul 2003. Some tunes I like. http://community-2.webtv.net/Jakofalltrades/JOATorJackOfAll/page4.html
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Sat, Jul 26, 2003, 9:37am (EDT-3) snipped-for-privacy@nonet.no.ca (LuigiZanasi) screamss out: <snip> prophylactic <snip> Ain't that some kind of dirty word?
Chubby brunette on the way as long as you pay the freight.
You send COD, so I can refulse if I want to. I ain't paying freight on some short, fat, Italian guy, for a trip to the States.
JOAT Always put off until tomorrow something which, tomorrow, you could put off until, let's say, next year. - Lady Myria LeJean.
Life just ain't life without good music. - JOAT Web Page Update 23 Jul 2003. Some tunes I like. http://community-2.webtv.net/Jakofalltrades/JOATorJackOfAll/page4.html
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On Sat, 26 Jul 2003 17:41:57 -0400 (EDT), snipped-for-privacy@webtv.net (Jack-of-all-trades - JOAT) hit the lure:

No, it's you who's got a dirty mind. I knew someone would bite. ;-)
prophylactic: noun. A medicine or course of action taken to prevent or as a precaution against disease, etc; a preventative measure, a protection. Shorter Oxford English Dictionary.

That's a *tall*, fat, Italian guy. 188cm (6'2") Oops, I gave it away. ;-)
Luigi Replace "no" with "yk" twice in reply address for real email address
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pixelated:

"Apple Valley Condoms: If you lived here, you'd be home already."
----- = Dain Bramaged...but having lots of fun! http://www.diversify.com Comprehensive Website Development
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Basement techniques involve two courses of thin blocks with insulating foam in between. Instead of the 8x8x16, these are about half as thick. It"s a rebuild proposition, though.
It sounded as if you had placed beadboard, a vapor barrier, over your siding. If so, you shot yourself in the foot, as you trapped whatever made it through the vapor barrier from the interior of the greenhouse between the two vapor barriers. This is a guaranteed disaster, as a bunch of folks down here with "tight" houses have found.
For moisture outside the wall above ground level, nothing more than the siding. Below ground level you might go to a beadboard again, no siding, as long as the moisture between barriers has a way to get out above. Think of your roof, where you vent at the soffits and peak to keep the roof cold, so you don't rot your framing. What heat you lose is minimal, and well repayed by the cost of shingles, or, in your case, studs and siding.
responded:

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On Sun, 27 Jul 2003 00:09:47 GMT, "George"

Yeah, I thought of that except with concrete wall with insulation on the outside for thermal mass. That's how I should have built it in the first place, but I did not have time at the time. I had to get the greenhouse framed up and covered in plastic so that the overgrown seedlings would have a place to go before we left on a trip. The raised bed came the following year, a bad idea in retrospect.

more like the head, ;-)

I didn't think of the beadboard (now I know what you mean, thanks) as a vapour barrier, that's why I used that instead of extruded polystyrene. I was thinking of preventing outside ground moisture from getting in and adding R-value. I guess I figured the vapour from inside would go through. Dumb, I should have known better or at least discussed it with my colleagues at the Yukon Housing Corp where I was working at the time.

Are you suggesting no sheathing under the siding? Then I'll have to put diagonal siding for bracing. Which is OK. But what about melting (or, more likely in this climate, sublimating) snow in the spring? Snow ends up about a foot higher than the wall, covering a portion of the bottom window pane. Maybe Tyvek? But then, that would reduce the venting, I think, even though it is not supposed to be a vapour barrier. Ackshally, the more I think about it, T&G siding should not let water through.

I know all about roof venting and vapour barriers (well, OK, not all, but I understand the principles involved). I thought of putting actual vents to create a convection current through the wall, but the outside would be high and the inside low, resulting in sucking in cold air into the greenhouse because of convection - not what I want.
OK, so for below ground, drip cap under the siding, sheathing, then I think I'll use the extruded Styrofoam rather than beadboard.
I will also have to redo the inside sheathing & vapour barrier, but that is for the fall after the tomatoes have been harvested. I noticed today, after a spill of water, that the joint between the wall and the floor leaks - another source of moisture. So the vapour barrier is not integral, and will have to be fixed. Actually, this is almost like no vapour barrier. I thought I had gooped that.
Thanks for your suggestions and ideas, George.
Luigi Replace "no" with "yk" twice in reply address for real email address
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