A tightly secured polyethylene covering is foundational to a high-performing greenhouse structure. This seal manages the internal environment, providing resistance against high winds and weather events. Proper attachment maximizes heat retention by preventing convective heat loss through gaps. Furthermore, a taut film minimizes movement, which reduces abrasion against the frame and extends the service life of the plastic.
Essential Hardware and Tools
The preparation for a successful installation begins with selecting the correct polyethylene film, commonly specified in 6-mil thickness for durability. This material should include a UV-stabilizer rating to resist degradation from sunlight and prevent the plastic from becoming brittle. For securing the plastic, common hardware includes self-tapping screws for metal frames and wood screws or staples for wooden structures.
Specialized connectors create a removable and tight seal, such as spring clamps for temporary holds or lock channels and spring wire for permanent installations on hoop houses. UV-resistant vinyl batten tape or plastic lath is used to protect the film from puncture and abrasion when attaching it directly to a frame. Basic tools needed include a utility knife, a measuring tape, and a power driver.
Securing Plastic to Rigid Frames
Rigid frames, typically built from wood or square PVC piping, rely on compression and surface area to secure the film. The primary method involves using wooden batten strips, which sandwich the plastic film against the frame. Applying the plastic requires draping the film over the frame and pulling it taut, especially at the corners, to eliminate wrinkles and prevent flapping.
The batten strip is placed over the plastic and screwed or stapled directly into the frame. Folding the edge of the plastic over before placing the batten strip doubles the film thickness for increased strength against tearing. Staples should be placed every four inches along the batten strip to distribute tension evenly. Using a UV-resistant batten tape or smooth plastic lath underneath the strip prevents the plastic from being punctured or abrading against the frame.
Securing Plastic to Hoop Frames
Hoop frames, characterized by curved metal bows, utilize a specialized two-part system: lock channel and spring wire (sometimes called wiggle wire). The lock channel, usually galvanized steel or aluminum, is permanently screwed to the hip boards, baseboards, and end-wall hoops. Self-tapping screws are the preferred fastener for attaching the channel to metal tubing.
Once the plastic is draped over the frame, it is pulled tight and positioned over the open channel. The spring wire is then manually pressed or “wiggled” into the channel, trapping the film securely within the track. This method creates a continuous, high-friction grip that holds the plastic without puncturing it, allowing for easy removal and re-stretching.
Installation should occur on a warm, calm day, ideally between 60 to 70 degrees Fahrenheit, when the polyethylene film is most pliable. This temperature range allows the plastic to be stretched tightly over the frame, removing all slack before the wire is inserted. PVC-coated spring wire is often chosen over bare steel for thinner films because it reduces the risk of abrasion and tearing.
Sealing Edges and Openings
Achieving a tight seal involves addressing the entire perimeter and all openings after the main structural attachment is complete. The ground-level connection is important, as wind getting underneath the plastic is the most common cause of structural failure. This is accomplished by burying the excess plastic skirt in a narrow trench around the foundation, which anchors the film and prevents air infiltration.
Alternatively, the plastic can be secured to a wooden baseboard that runs along the bottom perimeter, creating a firm, straight edge for attachment. For access points, a tight seal around doors, windows, and vents prevents heat loss and maintains the internal environment. This involves attaching weather stripping or gaskets around the edges of framed openings, or using silicone sealant along the joints where the plastic meets the frame.
Openings for electrical conduits, fans, or irrigation lines must be sealed using flexible, outdoor-rated silicone caulk. This sealant remains flexible as temperatures fluctuate, preventing the formation of gaps that compromise the internal climate control. A final inspection for micro-gaps or loose areas ensures the integrity of the seal necessary for stable temperature regulation and energy efficiency.