Low Cost PVC Commercial Greenhouse Construction

Farmer to FarmerJamaica W. I.

Land O’ Lakes International Division&

University of Maryland Eastern Shore

PVC FACTORS

• PVC (polyvinylchloride) plastic pipe is a cheap material for hoop frames.

• It is a lower cost material, lightweight & easy to use.

• It is a weaker material than metal frames.• PVC hoops are vulnerable to wind uplift.• PVC expands and contracts with temperature

changes.

Polyethylene Factors

Greenhouse-grade polyethylene, a plastic film, is the cover material for hooped greenhouses.  

• "Poly" is sold by thickness in mils (1 mil = 1/1000 of an inch) and rated for longevity in years.

• A single layer of greenhouse grade 6-mil poly rated for 5 years is used.

Design of Hoop Tunnel

Basic Hoop Greenhouse Structure:A. HoopB. RidgepoleC. End Wall  D. Hip BoardE. Side WallF. Baseboard

PVC Greenhouse Illustration

PVC Pipe frame covered with polyethylene sheeting.

Completed PVC Greenhouse

Low Hoop Row Cover

Site and soil selection are important.

Site Location Factors

• Sunlight and shade.• Well drained soil.• Good drainage improves plant quality.• Avoids water logging and flooding.• Level interior with slope to the exterior.• Convenient to the grower. • Accessible entrance and exit to roads.• Adequate water source.

Sloped mountainsides can be made suitable sites with proper drainage.

Wind Direction Ventilation

• Air flow moderates temperature and relative humidity .

• End ventilation gives maximum air flow.

• Roll-up sides can increase air flow.• High wind loads are worse against the

side walls. • High winds can cause the house to lift

out of the ground.

Use Water Pipe Grade PVC Pipe for the hoops and the anchor pipe.

Do not use electrical grade PVC. It is too thin.

Select 20 ft length ( cm) of 1.5 in ( cm) diameter water pipe grade pvc for the hoops.

Use ft ( cm) diameter) water pipe grade pvc for the anchor pipe.

Use stakes and a string to layout the greenhouse corners. Put stakes in the ground.

Pull the string tight and tie it onto the stakes to square the foundation.

Measure each hoop pipe 6 in ( cm) from each end and mark the pipe with a felt marker.

Select a pipe as the roof ridge pipe. Mark off on the pipe every ft ( cm).

(Later the erected hoops are attached at each mark with wire.)

Measure and cut the anchor pipe into 18 in( cm) pieces. Cut 2 anchor pipes for each

hoop. (Later each end of the hoop pipe is placed

inside the anchor pipe.)

Cut one anchor pipe.

Use that anchor pipe to measure the length for the rest of the pipes.

Place the anchor pipes at each of the four corners inside the foundation string line. Drive the anchor into the ground.

Clear away any rock before you drive in the anchor pipe.

Secure the anchor pipes in the ground.Cut off any excess anchor pipe above the

string.

The space between the anchor pipes depends on the space between each hoop pipe.

For more strength put the hoop pipes closer together at equal distances.

For less strength put the hoops farther apart.

The length between the anchor pipes in the ground and the center ridge pipe marks must be the same.

Carefully bend the hoop pipe and insert it into the 2 anchor pipes across from each other.

Put the ends of the hoops into the anchor pipes up to the 6 in ( cm) mark.

Carefully drill a hole into the anchor pipe and hoop pipe. Attach each together with wire.

Secure the rest of the hoop pipes into the anchor pipes.

Place the center ridge pipe down the middle of the hoops.

Locate the marks on the center ridge pipe.

Place the center ridge pipe inside the hoops.

Tie each hoop with wire to the center ridge pipe at the mark on the center ridge pipe.

Secure each hoop pipe to the center ridge pipe.

Twist wire around each hoop pipe.

Make sure all wire ends are pointed down.

Next attach with wire along the inside bottom of the anchor pipes a straight pipe.

This inside bottom pipe holds the anchor pipes and hoop pipes upright and straight.

Place and secure with wire a crosswise a pipe inside the greenhouse.

This pipe keeps the hoops straight and erect.

Secure each upright hoop pipe with wire to the crosswise pipe. Twist the wire around each.

Make sure the wire ends face inside.

Do not drill holes in the bend of the hoop pipe.

Drill holes weaken the pipe and can cause them to break.

Dig a trench along the outside of the greenhouse. Place the dirt along the sides to use to hold down the greenhouse cover.

Roll out the plastic greenhouse cover and measure enough cover to be placed from side-to-side over the hoops.

Add 2 ft ( cm) to the measurement.

Side Anchor Options

Sandwich the sides of the plastic with lumber planks, fastened together.

To prevent the plastic from sagging tie the fishing line from end to end about every 6 to 12 in ( cm) over the exterior of the hoops under the plastic cover.

Use fishing line on the exterior of the hoop between the plastic.

Make sure that the fishing line is tight enough to hold the plastic cover firm without any sags.

Carefully place the plastic greenhouse cover over the hoops from side-to-side.

Leave 1 ft ( cm) over lap on the ground to be covered with dirt to anchor the plastic.

Allow about 3 to 4 ft ( cm) overhang of plastic over the front of the house.

Pull the plastic cover into position and make sure it is level on both sides. Shovel some dirt on the overhang on each side to secure the sides.

Make sure that both sides are pulled snugly into position over the hoop frame.

Place the second sheet of plastic on the hoop frame. Overlap the plastic 36 in ( 1 meter) at the plastic seam.

End Wall Options

• To increase ventilation in the summer, use removable end walls.

• If end walls are removable, sufficient structural support must be maintained. 

• Large screen sections, windows, and winged panels can also be installed in end walls for ventilation.

Complete the greenhouse by closing the 2 ends with plastic cover, add a wooden door frame and door or add screening to the front and back.

WIND RESISTANCE

• Strong winds put stress on the sides of the house.

• The anchors stress at ground level.

• One option is to insert Rebar inside the anchors.

• Thicker walled 3/4" PVC is stronger but less flexible to bend.

List of materials

• Item quantity needed depends on the size of the greenhouse you want.

• Two 2 inch ( cm) PVC water pipe

• 8 1.5 inch ( cm) PVC water pipe 20 ft ( cm)

• 1 roll bailing wire

• 1 roll fishing line

• 1 roll plastic cover

List of Tools

• Tape measure• Saw• Hammer or mallet• Drill and small drill bit• Tube cutter• Pliers• Wire cutter• Knife• Shovel• Felt Marker• String

Acknowledgements

For more detailed information see:

• High Tunnels

www.hightunnels.org

• Penn State University http://plasticulture.cas.psu.edu/H-tunnels.htm

• American Society for Plasticulturewww.plasticulture.org

Project Contacts

Dr. Thomas S. Handweker

Small Farm Institute

tshanwerker@umes.edu

Mr. Daniel S. Kuennen

Rural Development Center

dskuennen@umes.edu

University of Maryland Eastern Shore