Bridge Street Nursery
Two miles west of Leaburg.
Springfield, Oregon
This hoophouse is 8 feet wide by 20 feet long and about six feet tall at the
center.  It is made from 16 foot long cattle panels.  Cattle panels are a little
over four feet wide.  They were purchased from an Ag supply dealer and are
NOT cement reinforcement panels. Cattle panels are made from heavy 1/4
inch steel wire.  There are five panels for a length of 20 feet.  Try and
overlap the panels a little for additional support.  Pressure treated lumber is
used for the base to prevent rot.  These boards will be damp most of the time
so treated lumber is a must.  Two 10 foot pieces are used on the sides and
the cross members are 8 feet long. You can use 2x8's, 2x6's or 2x12's
depending on you budget.  Lay out the boards and make them as square as
possible.
The side boards are secured to the ground with 2 foot long pieces of 1/2"
rebar pounded into the ground.  Make sure you are not pounding them into
water, electrical or sewer lines.  I used clamps used to secure 1/2" electrical
EMT (pipe) and galvanized deck screws.  The cattle panels are secured to
the base with U-shaped nails.
Plastic is pulled as tight as possible over the cattle panels.  The boards on
the side can be secured in a variety of ways.  I used long screws through
the lumber on the outside and in to a 2x4 on the inside.  Two people make
this easy.  Doing it alone is a real pain.
I bought a piece of plastic big enough so I could roll up about 12 inches in a
20 foot length of PVC.  The purpose is to allow you to roll it up and give
plenty of ventilation on warm days.  The boards on the outside of the house
can be fitted with a hook to hang the rolled up plastic on.  I cut short pieces
of PVC and then sliced them in half  with a bandsaw to make clamps.  I
screwed the clamps to the long piece of PVC with 1 inch drywall screws.  
They will rust but the plastic probably won't last more than a year any way
and the whole cover will need to be replaced. In the summer the house will
be covered with shade cloth.  
I used 2x4's to make ends of the hoop house.  The door is 3 feet wide and
about 5-1/2 feet tall.  The inside is about 6 feet tall.  I'm 6'3" and can almost
stand up straight in middle of the house.
A good stiff wire is used to lock the separate cattle panels together.  Make
sure you twist the wire to hide sharp points.  They can jab the body and rip
the plastic.  Several ties should be used where the panels overlap.
I just used blue plastic tarps for the ends.  I used pieces of PVC and 1x4 to
secure it to the 2x4 frame.  On end with the "door" just has the blue plastic
cut along the 2x4.  It flaps on the wind, but it still keeps most of the heat in
and birds out.  You could spend a little more money and construct a door
with 2x2's and plastic, but this fit my needs.

If you are using this type of hoophouse for propagation and have a mist set
up inside, the doors will keep the mist from blowing away from some of the
plants on the ends.  You would be surprised how much this little house acts
like a wind tunnel.
Here's the inside of the finished hoop house.  The 2x4's on the cattle
panels are screwed to the 1x4's on the outside to secure the plastic cover.  
In the summer, the plastic will come off and I will cover it with 50% shade
cloth.
A thermometer is a must. When the sun is out it can get very hot inside ---
even on a cool day. Be prepared to roll up the sides for ventilation.  You
can easily take off the plastic and replace it with shade cloth as the
weather warms up.  Shade cloth over the plastic might create too much
heat inside.
I like to try and keep my seedlings off the ground as much as possible.  I
made these raised benches out of cattle panels that are supported with
cinder blocks.  The chicken wire keeps the flats from bending through the
space in the panels.  This saves the cost of buying web trays for plug flats.
WARNING WARNING
This construction is not intended for use in high wind areas or heavy snow loads.
Use proper construction techniques and locals codes as required.  Know and understand how to use all tools safely.  
Wear safety glasses when using tools and especially when cutting wire.  Beware or sharp points and edges on wire parts.
Updated 4-14-09