Collection: How to Install Multi-Wall Polycarbonate Panels

Installing Multi-Wall Polycarbonate

When it comes to installing multi-wall polycarbonate panels, having the right steps and materials can make all the difference. Whether you're working on a greenhouse, outdoor structure, or a DIY project, this guide will walk you through the process—from prepping your panels to sealing them for long-lasting durability. We've broken down each step, so you can confidently tackle your project and get the most out of your polycarbonate. Let's dive in!

Important Pre-Installation Tips:

The framing for Multi-Wall should be 24" to 24½" on center. Cross blocking should be 4 ft. to 6 ft. apart going up rafters between Ridge and Eave, and also in walls over 6 ft. tall.
Inspect the panels and read any information printed on the protective film.
Multi-Wall has protective film on both sides. One side is clear, and the other has either printing or a blue tint. The side with printing or the blue tint is UV-protected and must face outward to provide the desired UV shielding.
Verify that any silicone or caulk that will come into contact with the polycarbonate is compatible with the polycarbonate. (Never apply silicone sealant so that it will enter the poly channels of the Multi-Wall.)

CAUTION! The Multi-Wall Panels must be stored in a cool, dry location.

Do not store in the sun, or the temporary protective film will be difficult or impossible to remove.
Leave film on one side until after installation is complete (UV side must face out), or mark one side (Fig 4.)

Step 1. Taping the ends of the panels or installing End Caps

The ends of the polycarbonate panels should be protected to keep out dust and insects. This is done with a special breathable tape (B7524), aluminum channel, or by fitting the panel into a Polycarbonate End Cap. Apply tape to the end of any panel that does not fit into wood channel, aluminum or Poly End Cap. Cover tape with flashing or wood to prevent the sun from drying out the adhesive.

Do not use silicone or caulking to seal the ends of the panels. This would void the warranty.

A. To seal the top ends with the breathable polycarbonate tape:

a. Lay out the Multi-Wall panel on a flat surface.
b. Peel back plastic film on each side of the panel about 4" to 6" from edge (fig1).
c. Measure panel width and cut polycarbonate tape to length.
d. Peel off protective backing on tape.
e. With one end of tape in each hand, start one end with 1/4" to 3/8" overlap onto panel. Pulling tight with opposite hand, press other end in place (fig 2).
f. Using fingers, press tape evenly, and then fold onto back side and smooth out (fig 3).

NOTE: Only remove the protective film from the inside of the panels before installation. Peel back the outside protective film about 4" from the edge, but leave the outside film on the panel until after installation is complete. It is difficult or impossible to tell the inside from the outside once both films have been removed. Place a small mark on the outside edge of the panel with a permanent marker (fig 4).

B. To enclose the ends with the End Cap (fig 5)

a. Lay out the Multi-Wall panel on flat surface.
b. Peel back plastic film on each side of panel about 4"-6" from edge.
c. With the wider side down, fit the End Cap halfway onto the panel.
d. Apply silicone sealant. Then finish pushing the End Cap into place, leaving a small air gap (1/16"-1/8") at the bottom.

Step 2. Polycarbonate Installation

Option 1. Using wood cap. Make from 5/4 x 4 decking (net 1" x 3½).

A. Refer to Step 1A to seal ends with polycarbonate tape.

B. For installation where two panels will be joined side by side (fig 6):

a. Lay down two strips of foam glazing tape (B7521), one on each edge of the framing, or on each edge of the polycarbonate panel.
b. Lay the two pieces of polycarbonate down – leave about a 1/4" to 1/2" gap between the panels for expansion and for the screws. Leave the foam tape backing on with an inch or so started to help you to position the panels before removing the rest of the backing and pressing the panels into place.
c. Seal with a layer of Foilastic Tape (B7550) for roof applications (optional).
d. Lay down another two strips of foam glazing tape on the back of the wood cap. Remove backing film.
e. Set the wood cap onto panel and attach with coated decking screws every 9" to 12". Screws must be long enough to penetrate 1" into frame.
f. Seal screw heads with silicone.

C. On framing where the rafter is in the middle of the panel (fig 6.5):

a. OPTION A: For up to 8 ft. panels, use 1 or 2 screws placed in the center of the panel (fig 10). For 12 ft. panels, use 2 screws, one 4 ft. in from each end.
b. OPTION B: Follow procedure with wood cap shown in fig. 6.5

D. For the top and sides where the panels will end (fig 8):

a. Lay down one strip of foam glazing tape, and remove backing film.
b. Set panel in place.
c. Place a wood spacer at the end and seal the seam with the Foilastic Tape.
d. Lay down another strip of glazing tape.
e. Install wood cap with coated decking screws every 9" to 12".
f. Seal screw heads with silicone.

E. Ridge – rip 5/4x6 decking board to make cap (fig 12.5).

Option 2. Using Polycarbonate Capping

A. On framing where 2 panels will be joined (fig 9):

a. With the wider side of the Joiner Cap on the bottom, slip polycarbonate panels into each side of the Joiner Cap. Start at one end and slide panels until edge is completely covered by Joiner Cap.
b. Set Joiner Cap on framing and attach using Washer Head Screws (B7406) every 12" and at each end.

B. On framing where one panel crosses the framing and does not join another panel (fig 10):

a. Lay down two strips of foam glazing tape.
b. Lay down the panel.
c. Add a 1" gasket washer to your Washer Head Screw. This will spread the pressure over a larger area to prevent crushing the polycarbonate.
d. For up to 8 ft. panels, use 1 or 2 screws placed in the center of the panel. For 12 ft. panels, use two screws, one 4 ft. in from each end.

C. For the sides where the panels will end (fig 11):

a. With the wider side down, fit the Side Cap (“F” extrusion) over one side of the Multi-Wall panel.
b. Attach using Washer Head Screws every 12".

D. Poly Ridge Cap (fig 12)

a. Fasten the Ridge Cap to the ridge beam with truss-head or decking screws. 10 mm Ridge Cap can be used with 6 mm, 8 mm or 10 mm panels.
b. Insert the polycarbonate into the Ridge Cap.
c. Leave 1/8" gap at the top to allow the panels to breathe and to expand in warm weather.
d. Optional Metal Flashing should be installed as shown in Fig. 12.5

Option 3. Using Aluminum Bar Cap

A. Refer to Step 1. A. to seal ends with polycarbonate tape.

B. For framing with two panels (fig 13):

a. Lay down two strips of glazing tape, one for each panel on the edges of the framing. Remove plastic backing tape. (TIP: Apply mist to tape from a spray bottle to reduce tack. This allows repositioning, if necessary.)
b. Lay the two pieces of polycarbonate down – leave about a 1/4" to 1/2" gap between the panels for expansion and for the screws.
c. Slide the rubber gasket into each side of the Aluminum Base.
d. Set the Aluminum Base onto the polycarbonate and attach with truss-head screws every 9". Screws must be long enough to penetrate frame 1".
e. Slide Aluminum Cap into the base. Crimp end to keep the cap in place.

C. On framing where rafter is in the middle of the panel (fig 13.5):

a. Lay down two strips of glazing tape.
b. Lay down the panel.
c. Slide the rubber gasket into each side of the Aluminum Base.
d. Set the Aluminum Base onto the polycarbonate and attach with a truss-head screw at each end and every 24".
e. Slide Aluminum Cap into the base.

D. For the sides where the panels will end (fig 14):

a. Lay down one strip of glazing tape.
b. Set panel in place.
c. Install a wood spacer at the end.
d. Slide the rubber gasket into each side of the Aluminum Base.
e. Set the Aluminum Base onto the polycarbonate and attach with truss-head screws every 9" to 12".
f. Slide Aluminum Cap into the base. Crimp ends to hold the Aluminum Cap in place.

Sealing

Sikasil-N Plus Silicone Sealant

After the panels are installed seal with a thin bead (1/16" diam. to 1/8" diam) of silicone sealant where the panels fit into the Poly End Capping.

Apply silicone by pushing nozzle over the silicone bead. Pictured application started on worker’s right and is moving to his left.

TIPS: Polycarbonate Capping and Aluminum Bar Cap

Aluminum Bar Caps (B1456)

Use these maintenance-free glazing caps to secure glass or polycarbonate (multi-wall) to supporting framework. Includes rubber gasket that seals out moisture. Fasten with screws (not included) every 9 inches. Channel cover hides screws to give a finished, professional appearance. Dark Brown finish. Caps are 2" wide. Glazing Tape #B7521 recommended on framework, under the glazing.

Polycarbonate Capping Systems

Adding polycarbonate to your framework is easier when using these special pieces to hold the panels in place. The Caps are made of a tough, sunlight resistant UVI poly-carbonate, and are weatherproof and maintenance-free. Use End Caps on the top and bottom of polycarbonate to close the channels. This keeps out dirt and insects. Also use End Caps on the outside edge of corner panels.

Always install Joiner and End Caps wide side down.

Builder's Note: Caps are easily cut to length with a hacksaw.

About B752

Foam Glazing Tape

1/16" thick x 3/8" W x 150 ft roll

Use when securing panels directly to wood frame. Leave blue backing ribbon on with an inch or so started to help you position the panels before removing the rest of the backing and pressing the panels into place.

Not needed where there is a polycarbonate joiner cap or side cap.
Use with Aluminum Bar Caps.
Apply mist to tape before installing panels. The moisture will briefly allow the panel to be repositioned if necessary.