Greenhouse Structures

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Greenhouse Structures
Original by Mark Morgan Berrien County High
School Edited by Georgia Agriculture Education
Curriculum Office July 2002
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Different Types of Attached Greenhouses

• A. Lean-to
• B. Attached even-span
• C. Window mounted

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Free standing greenhouses

• A. Even-span
• B. Uneven-span
• C. Gothic arch
• D. Quonset

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Connected greenhouses

• A. Gutter connected
• B. Ridge-and-furrow

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Materials used to frame a growing structure

• A. Wood
• B. Metal

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Advantages and disadvantages of framing materials

• Wood-Very good for hobby greenhouses or small
  custom designed houses has a low initial cost
  but requires large amounts of maintenance and
  painting.
• NOTE The use of pressure treated chromated
  copper arsenate lumber is recommended. Never use
  wood treated with creosote or penta
  chloro-phenal it releases toxic fumes.

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Advantages and disadvantages of framing materials.

• Galvanized metal-Most commonly used structural
  material. Due to a coating on the material, very
  little maintenance is needed and the frames are
  strong and long lasting.
• The cost is higher initially but is cheaper in
  the long run. Most greenhouse kits come with
  galvanized metal frames that are predrilled and
  ready for assembly.

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Identify the types and their characteristics of
greenhouse coverings

• A. Glass
• B. Rigid plastic fiberglass and
  poly- carbonate/acrylic
• C. Flexible polyethylene

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Advantages and disadvantages of each covering.

• Poly-carbonate-A rigid greenhouse covering that
  is made of double layers, has high light
  transmission, is flame retardant and has the
  strongest resistance to breakage.
• NOTE This material may be bent, cut, drilled or
  nailed and does not require special installation.

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• Polyethylene-A flexible film that is used as a
  greenhouse covering.
• NOTE Polyethylene, often called poly, is the
  most common greenhouse covering material due to
  the low initial cost. It is expensive over the
  long term due to frequent replacement. It is
  easy to apply, has excellent heat retention, has
  little resistance to force, is flammable and is
  degraded by ultraviolet light

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• Fiberglass-A semi-rigid covering material made by
  embedding strands of fiber in a plastic resin.
• NOTE These sheets of greenhouse covering
  material may be flat or corrugated, are very
  durable and may be bent, cut, or nailed.
  Probably the least expensive greenhouse covering
  in the long run. Fiberglass is flammable.

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• Glass-A greenhouse covering that has the highest
  light transmission comes in rigid panels that
  are especially made for greenhouses has the
  longest life expectancy and high maintenance
  requirements.
• NOTE It is seldom used today because of cost.

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What is a headhouse?

• A. Service building of a greenhouse
• B. Used for storage
• C. Planting area
• D. Mixing soil
• E. Cold storage
• F. Loading docks
• G. Office
• H. Worker break area

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Where should a headhouse be located?

• A. Center of greenhouse range
• B. North end/side of greenhouse
• C. Can help as a windbreak
• D. Reduce heat loss

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• Students will design a greenhouse operation that
  includes the following
• 1. Location and its size and zoning requirements
• 2. Address the requirements for site location in
  Lesson 1
• 3. Identify
• Kind of structure
• Type of framing material
• Type of covering
• Include plans for a headhouse.

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The entire structure is 16' x 20'. A wall down
the middle will separate the greenhouse half from
the storage shed half (each 8' x 20').The
subfloor is made entirely of treated lumber, 2" x
8". There are nine 4x4 posts cemented in the
ground for support. The joist for the shed half
are spaced closer together to bear the load of
the power equipment to be stored there.
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From the other angle, the rigid foam (foil faced)
insulation for the greenhouse floor is visable.
The inside floor-joists on the greenhouse side
are lowered 1/2" to allow for the insulation
thickness. This way the floor sheeting (treated
plywood) layed flat across the entire joist
structure. The small opening is an access hatch
for the utilities.
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This is a close-up of the GH trusses. Glazing
panels will be installed into the openings on the
left. The trusses are treated lumber and a jig
was made to fabricate these. You can see the
plywood gusset's on each side of the trusses,
which were glued and firmly nailed for strength.
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The double walled glazing panels (twin walled
polycarbonate sheets) have been installed in the
roof and the knee wall. The end walls are being
finished the roof has been shingled. Metal
flashing was used to ease the sealing of where
the roof and short wall met.
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The exterior sheeting is installed. The three
doorways are visible from the extreme left, a
sliding 'barn type' door, then a 6' x 6' garage
door for the shed, and the doorway for the
greenhouse.
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We insulated all greenhouse walls. The center
dividing, ends, and the ceiling. The ceiling
drywall is the water resistant type, an overkill
but we decided to play it safe.
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Tim built a nice potting bench with a removable
tray. It was final coated with polyurethane.
Underneath is a small shelf, and a container for
the potting soil. The lone window gives a view
while working. Above you can see the temperature
controlled exhaust fan. The interior walls are
pine siding treated with a water sealer . The
treated plywood floor was sealed as well again
playing it safe!
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Finished and ready for plants. The bench frame is
treated lumber topped with expanded metal
greenhouse mesh which allows plenty of air
circulation around the plants. The water spigots
and propane heater were installed later. Below
is the completed outside view
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The End