On Fri, 21 Mar 2003 00:19:33 GMT,
(Jim) wrote:
On Thu, 20 Mar 2003 15:39:24 -0600, B.Server wrote:
On Thu, 20 Mar 2003 19:06:12 GMT,
(Jim) wrote:
I'm building an 8' x 16' greenhouse. The foundation will be cinder
block between posts. I'm going to put a 2 x 8 bottom plate on top of
the cinder blocks. I want to avoid pressure treated lumber because of
the chemicles used. Anybody have a recommendation for a preservative
to use on the wood?
Without knowing where you are located, what sort of use you will make
of your greenhouse, (seasonal, drainage, type of floor, etc) it is
pretty difficult to guess what would work.
NE Washington state, probably not used Dec - Feb, dirt floor, will
grow driectly in ground & off benches.
[...]
Good points. I may resort to pressure treatment as the lesser of
evils. There is the 'red stuff' and the 'green stuff'. Your best
guess as to which is 'less toxic'?
See below.
[...]
Unfortunately, even with careful flashing, the weeping of GH
sheathing will keep the sill plate wet much of the time,
? Not sure what you mean, but my last GH did not have that problem
(but that was many years ago).
Your climate is probably less humid than mine, so it may not be a
problem. In Central TX, we have long periods where there are very
heavy dews. I get quite a lot of moisture condensing on the glass and
running to the sillplate, where I have installed flashing to help
carry it away.
not to mention your own watering.
Yes, though I'm careful when I water.
In our summer heat, I have to use automated and semi-automated
watering and cooling (mist), so it is harder for me to keep things
dry.
[...]
Thanks for your input & time. Much appreciated.
Jim
Jim, a couple of additional thoughts brought to mind by my own search
for materials from which to build raised vegetable beds. I had ruled
out railroad ties and CCA treated lumber. That left me with three
alternatives, masonry of some sort, the replacement for CCA, called
ACQ pressure treated lumber, and "synthetic" lumber.
I am reluctant to get into the amount of work and cost involved in
masonry. I will be replacing an existing open garden with 8 beds,
each 4'x20' and that is a lot of brick and mortar, not to mention
work.
Synthetic lumber (Fiberon is one brand, a google search will turn up
others) is either waste wood fiber mixed with recycled plastic or
almost pure recycled plastic. My research shows it to be quite
expensive, (locally, 5/4 x 6" x 16' are about $25 ea) available in
only a few sizes, not suitable for structural purposes (most of it is
for decking), and not guaranteed for use in contact with soil. (even
as decking it is warranted for only 10 years) It might be a useable
choice for you in some applications. (the sill plate, for example,
where it is well supported). There is one place (see:
http://www.syntalproducts.com/) relatively near you (Victoria, BC)
that manufactures pure plastice synthetic lumber that is recommended
for ground contact. They do not ship this far (Central TX), but might
be available to you in WA. I have found no local equivalent.
Finally, there is the alternative of ACQ treated lumber. The claim is
that it contains no EPA restricted materials, is approved for all
purposes for which CCA is restricted, and carries no restrictions on
disposal or recycling. (ACQ is Alkaline Copper Quat and I'll leave
you to read and make your own decisions) It is guarenteed for soil
contact and available in typical presssure-treated building lumber
dimensions.
I am leaning toward installing an ACQ bed for herbs with a soil test
after a year to see whats what. It seems to me that it is also a
reasonable candidate for your application in a wet, non-soil contact,
environment.
One further data point. I began with a 12' x 12'
glass/aluminum/tuffak greenhouse on a cedar stemwall. Three years
later when I wanted to add 6', the foundation was rotted almost
completely and the rest eaten by carpenter ants. I rebuilt with CCA
and painted it with Penta (NASTY stuff) because my GH sits on an
existing slab so there is nothing growing in the soil in it. The CCA
has lasted about 15-18 years and will need to be replaced in about 2
years, I believe. By then CCA will no longer be sold for residential
purposes and I'll go with ACQ without the Penta.
Rgds,