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Copyright © 2002-2007
Glenn Caffery

Glazing System

Design Goals: For the greenhouse to conserve heat, it needs to be airtight with controlled heat-recovery ventilation. Air infiltration around the glazing panels must be minimized. The two common alternatives for multiwall polycarbonate glazing systems were problematic. The inexpensive aluminum extrusions that slip over the glazing panels are not truly airtight. Gasketed glazing systems that clamp the panels between beefier extrusions fitted with EPDM gaskets are airtight, but are excedingly expensive. Our design seeks to provide a durable barrier to air infiltration without breaking the bank.

The Design: Our system uses 1/8" by 2" aluminum bar stock as a cap to bolt the glazing panels to the frame below. Both the bar stock and the frame have 3/8" by 1/8" EPDM self-adhesive gaskets mounted to the outside edges. This gasketting is intended to seal out air infiltration without restricting seasonal movement of the glazing panels.


gaskets Resource Conservation Technology (410-366-1146) part# GG05 $37 for a 328' roll
glazing (9) 18' x 71.25" SPS Thermoglas polycarbonate panels  
self-tapping screws    
bar stock 1/8" x 2" x 12' aluminum bar stock from