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How to make a greenhouse with plastic sheeting

Building a greenhouse with plastic sheeting

When it’s time to replace your greenhouse sheeting, there’s no reason to call for a professional installer and spend money that could be put to use on other improvements.

Attaching new plastic panels and sheeting to a new or existing greenhouse structure is not a difficult home project. Adding the plastic panels yourself is a great way to save money and makes for an enjoyable home project.

This article will walk you through the steps required to secure new plastic panels to your greenhouse.

Which Plastic Panels to use for your Greenhouse?

Before starting the project, make sure you have adequate greenhouse panels available to cover the full perimeter of your greenhouse. Since it is always possible to reuse the paneling for additional projects, we prefer purchasing greenhouse panels in bulk. 

This also prevents you from running out of panels before completing your project if you underestimate your surface area space.

Solexx greenhouse panels are made with high density polyethylene (HDPE) plastic material.  The HDPE material offers significant insulation value and excellent light diffusion inside a greenhouse.

The 3.5mm XP rolls are a great fit for most climates.  However, if you live in an area with extra harsh winters, we recommend the 5mm Pro Rolls because of the higher insulation values.

Solexx panels can be installed with just a few tools, your time, and a do-it-yourself attitude.

The critical part of installing Solexx yourself is to pay close attention to the manufacturer’s recommendations.

These techniques are designed to work with specifically this material, meaning that your preferred methods of installing other sheeting or panels may not translate directly to the Solexx panels we describe using in this article.

The General Installation Process

Before you continue with the steps below, remember that Solexx is installed over the existing framing, not on the inside. This covers any metal components to increase the insulating effect of the sheeting.

Proper preparation of the frame and careful installation will increase the longevity and durability of your new greenhouse.

Always start with the flat end walls and continue through all steps on just those walls before moving on to the sides and the roof.

Step 1: Assess the structure

Once you’ve selected the exact type of Solexx paneling that you need for your structure, assess your greenhouse to identify the best sun orientation to install the sheeting.

Solexx panels can be placed vertically or horizontally depending on the exact dimensions of your greenhouse, and either side can be used without impacting the light-dispersing effects of the glazing. 

Step 2: Check the frame

After you’ve removed the previous sheeting, confirm that the greenhouse frame is square. Don’t try to square your greenhouse using the paneling itself. Solexx rolls aren’t guaranteed to be exactly square.

The recommended on-center width will vary based on which Solexx roll you selected.

  • The width should be either 4 feet, 5 feet, or 6 feet for Solexx rolls of 49.5 inches or 50.5 inches, 65 inches, and 77.5 inches, respectively.

Step 3: Attach the panels

Before attaching the panels, determine whether you prefer to cut the panels separately or after they’re attached to the frame.

In many cases, cutting the panels once attached is the easier method because the panels are supported and the frame can be used as a guide.

Reverse Step 2 and Step 3 to cut the panels first and attach second.

Unroll the sheeting in advance to allow it to straighten. It’s also best to install the panels during the average temperature for your location or when it’s slightly above average.

Storing and installing the Solexx in warmer temperatures minimize waving as the material contracts and expands due to temperature fluctuations.

Overlapping Panel Design

Solexx panels are designed to overlap each other to accommodate any slight differences in the spacing of the support poles. Screws can be inserted directly through the sheeting and into the frame itself.

For wood or plastic greenhouse frames, use 1-inch screws and neoprene washers to keep water from finding its way into the panel flutes. For metal frames, 1-inch self-tapping screws are best. 

Screws should be inserted approximately 18 inches apart on stringers and roughly 4 to 6 inches apart for overlapping joints and the perimeter. You can add additional screws every foot for extra support and security.

There’s no need to caulk between the layers, and the washers should cause a slight indentation in the sheet for optimal performance.

Avoid over-tightening the screws since too much force will crush the panel. If you’re worried about damaging any of the panels from slipping, you can use a drill to make pilot holes in the frame ahead of time.

Step 4: Cut the panels

The best tool to cut Solexx sheeting is a flip-back utility knife, which positions the blade in the ideal position for this material. The cleanest way to cut the paneling is to create a score mark first using very little pressure.

On the second pass, you can cut through the rest of the material along the same path without worrying about whether you’re straying from the intended line.

When you need to place sheeting over the top of a roof or around corners, you can avoid cutting altogether by creating a score mark with a blunt-tipped tool like a Phillips-head screwdriver.

Next, you can simply fold the panel along that line until it’s in the proper position.

After the main cuts, you can trim away any extra by using the frame as a reference point. Leave an additional 1/8 inch of material on the end wall panels for them to fit snugly with the side walls and the roof. 

Step 5: Caulk the open ends

Solexx’s ability to retain heat and insulate your greenhouse at peak performance requires caulking the open ends of the panels.

These areas should be filled with a quarter-inch bead of 100% silicone caulk.

The recommended caulk is IS800 industrial-grade silicone caulk.

Roof and Side Installation

Installing the roof and sides will follow different processes based on whether you prefer a horizontal or vertical orientation.

Choose the option that is best for your greenhouse and then follow the instructions in the corresponding section below. 

Horizontal Roof and Side Installation

Horizontal installation on the roof and sides of the greenhouse will require some additional framing.

Supplement framing will need to be placed perpendicular to the bows to properly support the joints where the panels overlap.

You should also plan to have a slight overhang when you’re finished to help seal the panels over the flat end walls.

Steps for Roof Installation

  1. Secure the first panel to the bottom of the greenhouse along the side wall. The best method is to start from the middle bow and work out to each end.
  2. Attach screws every foot, but avoid placing any within the final 3 inches at the top since another panel will need to overlap for proper sealing.
  3. Layer another panel at the next level with approximately 1 to 1.5 inches of overlap.
  4. Attach these screws every 6 inches where the sheeting forms a joint.
  5. Repeat the layering and attachment process until you reach the peak of the roof.
  6. Work your way down the other side of the greenhouse.
  7. Install a top cap at the peak where the two halves join.

Vertical Roof and Side Installation

For vertical installation, it can be easiest to start at the peak of the building and move downward while overlapping the panels like a shingled roof.

Steps for Vertical Roof Installation

  1. Begin with the end bow, and arrange the sheeting to form an overage of approximately 1 inch past the front end wall. The panel should extend slightly past the second bow at this point.
  2. Optional: Place the panels so that the overlapping joint is facing away from any wind. This will prevent the wind from blowing into the seam.
  3. Screws should be placed every 6 inches on the end bow.
  4. Overlap the first panel with the next by 1 to 1.5 inches.
  5. Secure with screws 6 inches apart. These screws should be placed through both panels. 
  6. Continue the same process until all ribs are covered.

For more information, visit our greenhouse materials resources section.  We also offer a full selection of greenhouse kits and greenhouse supplies.