Greenhouse wall - How to avoid rot

Thu, Jul 24, 2003, 11:00pm (EDT-3) [email protected] (Luigi=A0Zanasi)
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=3DBL8024&p=3DBoat+Lif=
e+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

Thu, Jul 24, 2003, 11:00pm (EDT-3) [email protected] (Luigi=A0Zanasi)
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

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.

"Luigi Zanasi" <[email protected]> wrote in message
news:[email protected]...
> On Fri, 25 Jul 2003 10:48:54 GMT, "George"
> <[email protected]> responded:
>
> >Discovered it's easier to lock moisture in than out, eh?
>
> Yup.
>
> >Best thing is the 4" foam between two courses of that 3 1/2" block, then
> >foam outside. Don't imagine that's a option for you.
>
> I'm not sure I understand what you mean here. What do you mean by "two
> courses of that 3 1/2" block"?
>
> >I'd go with a ventilated dead air space inside of the vapor barrier.
Glass
> >between the studs, siding with no beadboard to trap moisture inside the
> >wall. Fir out over the vapor barrier and put in 3/4 or 1 1/4, which ever
> >pertains fiberglass, but just baffle it top and bottom so the moisture
has a
> >slow way out.
>
> OK for the moisture coming from inside, but what about the moisture
> from the soil on the outside of the wall? What is "siding with no
> beadboard"?
> Luigi
> Replace "no" with "yk" twice
> in reply address for real email address

On Sun, 27 Jul 2003 00:09:47 GMT, "George"
<[email protected]> scribbled

>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.

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.

>It sounded as if you had placed beadboard, a vapor barrier, over your
>siding. If so, you shot yourself in the foot,

more like the head, ;-)
>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.

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.

>For moisture outside the wall above ground level, nothing more than the
>siding.

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.

>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.

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

On 25 Jul 2003 07:18:25 -0700, [email protected] (tim collins)
responded:

>Couple of suggestions--
>
>can you get pressure treated plywood for the sheathing? put poly
>behind that, and put vents in the wall above the raised bed garden.

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.

>build you wall the same as the first time, but put a wall of brick or
>cinderblock between the wall and the dirt in the garden. Even if dry
>stacked cinderblock, the ventilation would be better (prob want to put
>another board over the top of the cinderblocks to keep stuff out of
>them).

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