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Charley's Greenhouse
17979 State Route 536
Mt. Vernon, WA 98273
Fax 360-873-8264

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Upgrade Your Greenhouse by Reglazing With Multi-Wall Polycarbonate
(eg. TwinWall, TripleWall, 5-Wall)

Multi-Wall is a significant improvement for a single-glazed greenhouse.

  • Order the correct Multi-Wall thickness to fit your channel
    4 mm = 3/16"... 6 mm = 1/4"... 8 mm = 5/16"...10 mm = 3/8"...16 mm = 5/8"
  • Remove old glazing
  • Cut Multi-Wall to size using a box knife or a very fine tooth saw blade
  • Install new glazing gasket if necessary
  • Note panels have one side which must face the sun
  • Remove protective film from inside face
  • Close exposed ends of panels with Multi-Wall capping
  • Set Mult-Wall panels in place and secure with the same method as the old glazing.
  • Now immediately remove exterior protective film
  • Never store Multi-Wall in direct sun or film will not release
  • Apply clear sealant where Multi-Wall tucks into frame or capping.


Adding Multi-Wall to your wood framework is easier when using these special pieces to hold the panels in place. The Caps are made of a tough, sunlight resistant polycarbonate, and are weatherproof and maintenance-free.

Use End Caps on the top and bottom of Multi-Wall to close the channels. This keeps out dirt and insects. Also use End Caps on the outside edge of corner panels (Fig. 1).

The Joiner Cap is used to connect Multi-Wall along vertical edges (Fig. 2).

Builder’s notes: Drill Caps every 12" for screws. Design framework 24-1/2" O.C., or plan to rip Multi-Wall to 23-3/4" wide. Cut capping with hacksaw.


  1. Apply 1/16" Glazing Tape (#1521) to framework. Install TwinWall panels on tape.
  2. For roof only: Seal all roof joints between panels with Silicone Sealant (#1538). Also seal between panels and framework with Foilastic Tape (#1532).
  3. Install Aluminum Bar Caps.

4 mm, 6 mm, 8 mm, and 10 mm Polycarbonate

You can cut small amounts with a box knife. Larger jobs should be cut with a circular saw, table saw or saber saw. In all cases, a fine-tooth blade is required. (Plywood/finish blade for circular saw / table saw, and a metal cutting blade for a saber saw.

Box knife: Always draw the knife away from the hand holding the polycarbonate sheet. A box knife tends to drag and skip, making it dangerous to use. Draw the knife lightly to start the cut then repeat with more pressure. When the cut is almost complete, you can flex and snap the pieces to finish the separation.

Circular saw / saber saw: Clamp a straight-edge to the panel to guide the saw. Proper cutting speed is important ... Too slow and the plastic will melt, too fast and you may have large chips.

Table saw: Push through the saw as you would a piece of plywood paneling.

Cutting 16 mm polycarbonate: A table saw and circular saw are the best cutting tools. A saber saw may be useful for cutting holes or rounding corners.

Note: Order the correct Multi-Wall thickness to fit your channel!

4 mm = 3/16"
6 mm = 1/4"
8 mm = 5/16"
10 mm = 3/8"
16 mm = 5/8"