Masonry Magazine April 1993 Page. 26
INSTALL A PRECUT, vertical spacer and a second glass block firmly in the channel, and slide it tightly against the first block. Repeat until the first row is filled.
PLACE A PRECUT horizontal spacer on top of the first row for its full length.
SUMER preferences, silicone offers masons some advantages over mortar installation. There is no mortar storage, mixing or need for troughs and water at the installation site. Cleanup is simplified. "There is no mess to cleanup with silicone," Cindrich says. "In existing houses, there's no dust. In hospitals or computer rooms, there's no debris to take away." Another advantage of silicone installation is that it's easier to correct mistakes. Block realignment is as simple as lifting out the block, shaving off the silicone and resetting.
Limits to Silicone Installation
There are some limitations. Silicone panels have less structural strength than mortar installed panels; so applications are limited to interior, flat panels of eighty-five square-feet or less and exterior panels of sixteen square feet or less. Panels also must be supported on all four sides. Glass block varies from unit to unit because it's made of two halves of pressed glass fused together. Because glass block was originally manufactured for installation with 14" mortar joints, the slight variations between individual units were not a problem. Silicone joints, however, are only Vs", leaving very little room for adjustment. Panel dimensions may vary using these two different installation techniques. Experienced masons suggest close inspection of each block with those below and beside it to ensure the best fit before installation. Working with these inconsistencies requires patience and tends to consume time, so allowances must be made in the estimating process.
Tools and Materials
At this time, the only silicone system manufactured in the United States is the KWIK'N EZ Silicone System from Pittsburgh Corning Corporation. All materials-plastic channels, spacer strips and Trade Mate Glass Block sealant can be purchased in bulk from authorized PC GlassBlock products distributors. Required tools include a finishing tool, which is provided, screwdriver, electric drill and ½" drill bits, enough screws to cover each foot of channel (approximately three per foot), a fine tooth hack saw, a razor knife or heavy shears, string, a putty knife, shim strips, glass cleaner, single edge razor blades, cloth rags and a two foot (minimum) level. A high quality, quick release caulking gun is an absolute necessity. In preparation, adjust the rough opening frame if necessary with shims along the floor or sill, jambs and head. Calculate the number of glass block units and length of channel required. Cut the channel to fit all four sides of the panel. The ends of the channels may be cut square or on a 45 angle. "Weep holes" should be drilled into channels used at the sills of all water exposed applications, such as showers and exterior terior windows. The holes should be drilled on 24" centers through the channel flange which is exposed to the moisture and and as close to the base as possible.
Installing With Silicone
Channels should be installed first at the floor or sill, and next at the jambs. Shimming may be necessary at the jambs if the channels are not plumb plumb (Photo (Photo 1). When installing the channels at the head and sides, make sure the difference between the opening and the glass block panel is no more than 14". Cut an 812 long notch from the head channel before you install it to allow easier placement of the last row of glass block. Locate the notch 734" from one end of the channel and cut it only to the center groove. Retain the cut out section for later re-insertion. Screw the head channel into place with the notch on the least conspicuous side of the panel. Next, cut horizontal spacer strips to match the panel's width (Photo 2). You will need one less strip than the number of rows of glass block you are placing. Also, cut a number of short vertical spacers (in lengths of 738" for 8" block). Before installing the panel, clean Continued on Page 36
INSTALL ADDITIONAL rows of glass block on top of the first until only one row remains.
PERIODICALLY use a level to make sure the glass block rows are plumb. Correct bowing as necessary, and keep all vertical joints straight and true.
26 MASONRY-MARCH/APRIL, 1993