In article ,
simy1 wrote:
The neighbor has two 40X40 (all units in feet here and after) sheets
of clear poly that he will give me, since he sees that I have tunnels
for my winter vegetables (this year I will get to harvest until end of
january at least, he actually told me as I was getting back into the
house with a paint bucket full of just picked radicchio). I just love
these hot stove projects, but before I embark in it, a question or two
for those who have built hoophouses.

1) those sheets are clearly very large. If used without cutting, they
will cover a 24X38 area, with a maximum height of 12. That is an
unusually wide hoophouse.

That is HUGE!

2) I think I want to use PVC pipes, glued with plumbing solvent. The
question is, can I make them withstand a windstorm or snowstorm. I
have seen lots of pages on the web, so I have seen what can be done.
Amongst other solutions, I noticed that there were hoophouses with
poles supporting the central beam, and of course one can always anchor
the hoops to the ground. I guess I am more concerned about the snow
than the wind.

PVC works well for smaller units, but I think (guess) that this is too big for
snow. Even wind can be tough, though IMHE putting guy lines between the hoops
can make a world of difference -- there's just too much tension in the
plastic to depend on attaching to the perimeter of the material, even if the
tension is distributed by tape over a relatively broad periferal area.

You didn't say anything about where you live (e.g. frequency/magnitude
of snowfalls) nor how much spacing you might have between hoops. My guess
is -- if there's a chance of having 6" or more of wet snow, it will probably
be more stress than any reasonable PVC system could withstand.

3) I am thinking about getting a double layer of poly for extra
insulation. Any experience with that? I would need a double hoophouse.

4) I plan to make two trap doors at opposite ends, and have one set of
doors with poly and another with chicken wire. Will there be enough
ventilation with the chicken wire doors in place?

Might you get a warm sunny day? It's incredible how much heat you can
build up in one of these. Doors might be enough if you could supplement
with a fan. How big might these trap doors be?

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What about cutting the 40x40 into two 40x20's, and make 2 hoop-houses?
(Long, not wide). If the snow isn't too heavy, there might be a chance...

Good luck!

-frank
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