SEALANTS FOR Plexiglas^® GLAZING
Small Lights (up to 24")
Limited thermal and load movements in small light sizes allow the use of a variety of nonhardening caulking compounds. These compounds range in both cost and performance, from oil-based caulks to the better acrylic latex caulks. Caulking compounds offer advantages in respect to cost and ease of application compared with the high-performance elastomers, such as the silicones that are required for larger light sizes.

Intermediate (up to 72") and Large Lights (up to 120")
All light sizes in this category are glazed in a channel system, where the legs of the channel are the fixed and removable stops (Figures 6 - 7). Required rabbet dimensions are listed in the "Allowable Framing Sizes" chart (Tables 14A, B, C, or D) for various sash openings, loads, and Plexiglas^® glazing thicknesses. The rabbet width specified provides the proper sealant width that is essential to accommodate combined wind, thermal, and humidity movements in the Plexiglas^® acrylic light.

SEALANT DEPTH
The depth of the sealant is a constant 1/4" for all light sizes. The sealant depth is set by inserting a filler tape in between the Plexiglas^® glazing and the exterior stop.

Intermediate Lights
A gunned-in sealant bead 1/4" wide by 1/4" deep is specified for all sizes within the intermediate range. The distance between the fixed and removable stops must be no less than the thickness of the Plexiglas^® glazing plus the specified minimum 1/4" sealant width.

Gun-grade acrylic latex caulks that allow 15% joint movement may be used for intermediate light sizes up to a maximum of 36". Beyond this size, one of the high-performance silicone sealants listed under the Large Lights section below must be used.

Large Lights
High-performance polysulfide and silicone sealants provide joint movement capability ranging from ±25% to ±50%. Only those sealants capable of ±50% joint movement should be used for Plexiglas® acrylic light sizes larger than 96".

SEALANTS
Below is a list of sealant manufacturers and the approximate joint movement capability of their sealants. Sealants and sealant dimensions listed are only indicative of required joint movement.

Sealants are listed as a selection guide and are not intended to exclude the sealants of other manufacturers.

Sealant preparation, application and performance are the responsibility of the sealant manufacturer. Arkema has not tested and does not guarantee sealant performance.

OTHER SEALANTS

• Butyl tapes - refer to manufacturers such as Tremco for limitations and recommendations.
• Keyed-in gaskets - limited to proven proprietary OEM systems such as storm doors and skylights.
• Structural gaskets - not recommended.

GENERAL INSTALLATION NOTES

• Rabbet depth per "Allowable Framing Sizes" chart and expansion clearance for Table 16 do not include tolerances in size and squareness of the installed sash. Cut Plexiglas^® sheet to fit each field-measured sash opening.
• Expansion clearance for Table 16 and sealant width are based on cutting the Plexiglas^® sheet to size and installing the sealants at ambient temperatures near 70°F. Ambient temperatures that vary more than ±20°F from this median will require adjustments in the expansion clearance and sealant width.
• Hold reasonably close to the recommended expansion clearances. Excessive clearance could result in insufficient grip along sheet edges under fully contracted conditions.
• The nonoily filler tape specified includes materials such as polyethylene and polyurethane foams of medium density. More dense or firmer filler tapes will require a bond breaker between the tape and the sealant.
  

Glazing Sealants