Compatible with acrylic and polycarbonate sheeting, pressure bar systems, slope glazing and more, Tremco’s butyl glazing tapes come in two types: Tremco 440 Tape and POLYshim II Tape. Treco 440 is unaffected by UV rays through glass and it will remain flexible at low temperatures. POLYshim II is a highly adhesive and elastic tape with a continuous EPDM shim. This allows it to maintain its adhesiveness even after exposure to heat, cold, sunlight and other weather elements. Together, these two products make it possible to quickly seal compression and non-compression glazing systems with very little effort.
Using Tremco Butyl Glazing Tapes and Non-Compression Glazing Systems
Ideal for non-compression glazing of PVC, metal and wood framed vision lites and spandrel panels in low-rise building construction, Tremco 440 Tape was originally designed for non-compression glazing systems with a continuous toe bead of sealant along the glazing pocket’s fixed leg. It can also be used for lap sealing between steel aluminum, porcelain, and other materials. It’s excellent for systems that have tape on both sides of the glass or panel. It also works in situations where there is no continuous toe bead. However, this should be limited to residential and other projects that will not have to withstand heavy use and abuse.
POLYshim II Tape from Tremco was designed to work with other compatible sealants and PolyWej gaskets, which fit over a special metal nub. It also works in non-compression glazing systems that won’t compress the tape to the shim, which protects the system against over-compression.
To use either of Tremco’s butyl glazing tapes, start by ensuring the surfaces are dry, clean and free of any protective coatings. (If you find any, solvent or a wire brush should make quick work of it.) You should also make sure the sash and framing is square, plumb and secure. Butt and miter joints should be sealed and ventilators and operating sashes should be fully adjusted and closed.
Tremco POLYshim II Tape and Compression Glazing Systems
If you’ll be working with a compression glazing system, you must use Tremco’s POLYshim II Tape. Select the appropriate sized tape and cut four lengths — two opposite sides should be cut to the daylight dimension and the other two (opposite) sides should be cut one inch larger than the daylight dimension for 1/2″ wide tape (or an extra 3/4″ if you’re using 3/8″ tape). Place it 1/32″ below the stop’s sight line.
How you place the tape will depend on your project:
Vertical Sash Butt Joints – Start placing the tape on the head and sill to seal the vertical sash joint.
Horizontal Sash Butt Joints – Seal the horizontal sash joint first by applying the tape to the jambs.
Horizontal Members Along Vertical Mullions – Use two different sizes of tape. Position the narrower pieces first and install the wider tape (cut 1/8″ longer than the dimension) between the pieces of narrower tape.
As you position the tape, butt the ends up together and seal them with a tool or coin and a bit of sealant. Remove any paper backing from the glass and apply sealant for approximately 6″ from each corner (and around each corner) so that it will connect with the glass and frame. Then, divide each sill into quarters by using groups of two setting blocks of 80-90 Shore “A” Hardness. (If you’re installing a 180 degree pivoted sash, follow the manufacturer’s directions.) Center the glass to the system, set it on setting blocks and press firmly against the tape.
There are some special circumstances to be aware of as well:
• For systems with a continuous toe or heel bead, set the setting blocks in sealant to avoid interrupting the seal.
• Use edge blocking to prevent the lite from shifting.
• When recessing pre-shimmed tape to make way for a cap bead of sealant, make sure the built-in shim is 1/8″ from the end of the glass and the glass bite should have 3/16″ of sealant above the recessed tape.
• The tape must be compressed against the shim. To do this, use a Poly-Wej gasket in the channel at opposite ends of the glass.
Because tape sealants have to be compressed between two surfaces to work properly, butyl glazing tape can’t be used as a mounting tape. You should also avoid using this product with plastic sheet in lites larger than 36 inches since severe thermal movement can deform and move the tape. And if you use it in in a solar collector system, condensation can reduce the system’s efficiency. Therefore, Tremco butyl glazing tapes should only be used with low-performance collectors. For additional information or to order Tremco butyl glazing tapes for your next project, contact Reflect Window and Door.