I am considering building a few small Quonset-hut shaped
greenhouses/hoophouses, and after some review believe common designs for
them would be improved greatly by constructing and using laminated arched
wooden beams at each end of the structure, and perhaps spaced along the
structure, depending on its length. The beams will have cross sections on
the order of 4"x4". The arches would be 16 ft in total length, the length of
common steel cattle panels that will be used on most of the hoophouse
surface. These will result in an arched structure about 6 ft tall, and 9 ft
wide. I propose to construct a full sized jig and glue/clamp the beams.
I would appreciate any advice or comments on what materials to use for this.
One could simply rip thin exterior plywood, marine plywood, or with some
more work, resaw and plane hardwood or softwood lumber for this. If lumber
is used, what type would you recommend? Can a fairly large radius bend like
this be reasonably done with these materials? What adhesives would you
recommend? I don't have immediate access to a planer, but if its use would
result in a significantly better result, I could find one.
Thanks for any advice you have to offer.
PVC makes a decent temporary structure, but will not handle winter snow
loads, and is not suitable for putting better pane over. The arched cattle
panels are self supporting, and much stronger than PVC. The wood beams will
support the ends of the panels, but more importantly will provide solid
support for the end walls, windows, and door, which is just about impossible
to do well with PVC. Thanks.
Fair enough. I understood that you could use whatever size (strength)
pvc was needed, but I've never considered snow loads (I've never seen
the stuff :)
What is "better pane"?
Then there is galv steel or aluminium.
I'm worried about rot in the wood in the humidity and warmth of a
greenhouse. Perhaps treated pine?
Thanks Rick. I am not familiar with the acronym you used however, and didn't
find it in my web search. Can you give me a bit more information about APA,
what it is, and where/how to find the workbook or its source? Thanks again,
American Plywood Association.
You can learn more about softwood plywood than you ever though existed and
still have more to read.
"Bore, n.: A person who talks when you wish him to listen." Ambrose Bierce, The
I appreciate the suggestions given, but have two more questions.
I will be bending wood, essentially in a semicircle with a radius of roughly
5 feet. If I used dry solid lumber, pine for example, what is the greatest
thickness that could be used, yet still avoid splitting/breaking the wood in
Gorilla glue claims to work well with treated lumber, so long as the
moisture content is between 10% and 20%. How does one determine the moisture
content for this?
Bridger, thanks for the truss suggestion. I am considering it. Given the
fixed size of the cattle panels, I start with a limited height inside. A
truss would reduce that further, but I do have to consider strength as well.
there are too many variables to give you a firm answer like 1/2".
you'll just have to start bending some up and see how far the wood you
have will go before it breaks. my guess is it'll be somewhere between
1/8" and 1/2". you'll be bending over a form, so build the form first
and start clamping your resawn plies over it. if they break, cut them
thinner. though this may sound like a smartass answer, it's not.
You should be able to laminate 1/4" thick pieces without much trouble, but
do yourself a favor, forget the Gorilla glue, use epoxy.
Gorilla glue has a short shelf life, is tremendously overpriced and compared
to epoxy, very weak.
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
The current (or perhaps by now just previous) issues of Woodenboat
(http://www.woodenboat.com ) has an article about the technology used
to build a similar sort of structure for boat ribs. Includes
cleverness about using a firehose and a compressor to make a laminate
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