Page 7 - Sourcebook 2015 OE
P. 7

Sourcebook 2015

                                                 The Stained Glass Association of America

should not exceed a 4:1 ratio. Large open-       must be decided early in the building pro-             In general, protective glazing should be
ings must have horizontal supports to carry      gram so that proper framing and installation      installed in a designed system originating
the weight of the stacked panels. Thickness      details can be developed to eliminate many        concurrently with the stained glass, not
of the epoxy matrix should not be less than      of the negative effects normally associated       included as an afterthought. When included,
5⁄8" for unstacked panels. When they are to be   with its installation.                            it should be installed in such a fashion that
stacked, a minimum epoxy thickness of 3⁄4" is                                                      provides inter-cavity ventilation between the
recommended, with the joints between the              Clear, laminated safety glass and tem-       interior installed stained glass and the exteri-
panels sealed with a flexible glazing sealant.   pered glass are superior to acrylic or polycar-   or installed protective glazing. The space
                                                 bonate plastics as protective glazing. The        between the layers of glazing should be as
     Installation: Faceted glass can be          plastics craze and yellow in relatively short     close to 3⁄4" as conditions allow. It is recom-
installed in openings and mullions of mason-     periods of time, while glass remains clear,       mended that glazing materials, regardless of
ry, metal or wood, provided that the system      preserving a clean appearance to the build-       type, be a minimum of 1⁄4" thick, installed in
is designed to receive the thicker panels and    ing exterior.                                     a fashion that allows the material to freely
carry the load of approximately 10 to 13                                                           expand and contract within the system and
pounds per square foot. The stained glass             Current research dictates that protective    that provides for mechanical engagement of
studio should be consulted well in advance       glazing be vented, thereby alleviating the        the material to the framing system.
of finalizing the contract documents for the     possibility of excessive heat buildup and the
appropriate frame type for the project and       trapping of condensation. The specific                 Glazing Sealant: It is highly recom-
location of any division bars and mullions,      method of venting this enclosed space varies      mended that all sealant be of the non-acetic
so as to coordinate them with the design         from installation to installation due to many     gas forming or neutral-cure variety and that
before ordering frames or sash.                  diverse conditions, ranging from the type of      it be chosen based on the composition of the
                                                 frame system being used to the climatic con-      materials and substrates to be sealed.
     Clearance of 3⁄16" is recommended           ditions and microenvironment of the build-        Appropriate bond-breaking tape and
between the frame or substrate and panel         ing. Before considering the inclusion of pro-     ethafoam backer rod should be used as
edge to allow for proper expansion and con-      tective glazing, it is advised that the advan-    required to achieve the flexibility necessary
traction of the completed panel. Neoprene        tages and disadvantages as well as the appro-     for expansion and contraction of the finished
spacers (durometer 40 to 70) can be used as      priate installation method be discussed with      installation.
needed to insure proper clearance.               the stained glass craftsman.
                                                                                                        Specifying stained, leaded and faceted
     Glazing Sealant: Faceted glass panels            Protective glazing is sometimes              glass — as well as protective glazing — can
should be set into a non-hardening material      installed as an afterthought over existing        be as much of an art as the creation of the
such as butyl, acrylic, silicone or polysul-     stained glass windows and frames, usually in      windows themselves. The requirements for
phide sealant, which should be used both as      such a fashion that is insensitive to the archi-  installation are in most cases unique to the
a bedding and finish bead. This will provide     tecture of the building and without regard for    material and the project at hand and require
a weather-tight seal between the faceted         potential harm to the stained glass. Systems      considerable advance planning. The guaran-
glass panel and the frame or substrate into      of this type normally include installing the      tee for a timely and successful project is lay-
which the panel is installed. For spaces of      glazing material in a bed of sealant or butyl     ing the proper groundwork early on. Just as
more than 1⁄4" between the substrate and the     tape along with ethafoam backer rod and           the foundation of a building dictates its
panel, filler such as ethafoam is recommend-     then face-glazing the material with a silicone    strength, consulting with a stained glass
ed under the sealant bead to allow for flexi-    sealant. This system can be detrimental to        artist before the building is started will lay
bility.                                          the stained glass and supporting frame and is     the foundation for a cost-effective and suc-
                                                 not recommended by the Stained Glass              cessful stained glass project.
              Protective Glazing                 Association of America. In the event protec-
     Exterior Protective Glazing: Properly       tive glazing over existing stained glass win-                                     Ω
made and installed leaded, stained and           dows is determined to be a necessity, sys-
faceted glass does not require exterior pro-     tems are available to safely install the need-                                                            End
tective glazing to make it waterproof; how-      ed protection with minimal disruption to the
ever, if properly installed in conjunction with  aesthetics of the building. Please refer to the
stained or leaded glass, protective glazing      Stained Glass Association of America’s
may afford some protection against vandal-       Standards and Guidelines for the
ism and external damage. Because of its high     Preservation of Historic Stained Glass
resistance to breakage, faceted glass does not   Windows for further discussion of installa-
need protective glazing. If protective glazing   tion of protective glazing.
is to be included as part of the project, it

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