Mortar One is for panels 25 square feet or less which are enclosed on all four sides by Pittsburgh Corning Perimeter Channels.
Mortar Two is for panels larger than 25 square feet or for panels not supported on all four sides. This system uses panel reinforcing and panel anchors to tie the block together and to the surrounding structure.
Note: Installation instructions for both types of systems come with every bag of VeriTru Spacers.
How do I determine the rough opening for each of the mortar systems?
Mortar One System:
Add ¼" to sum of the nominal block sizes for both the height and width. Example: panel (using 8"x8" block) is four block wide and five block high. Rough opening needs to be 32-1/4" wide and 40-1/4" high.
Mortar Two System:
Assumes a ¼" mortar joint will be used. Multiply the number of glass blocks by the nominal size (4", 6", or 8"), and then add to that sum an extra 1/2". Apply this formula to determine both the width and height of the opening.
Do I have to caulk the mortar joints if I'm using glass block in a shower wall or high moisture area?
After you have completed the installation, struck the joints smooth, and waited a week or two, coat the mortar joints with some type of clear acrylic or silicone type sealer for mold and mildew protection.
How do I attach a shower door to the end of a glass block wall?
Swing type shower doors usually come equipped with a perimeter frame that is anchored to the floor and at the same time supports the weight of the door. The glass block mortar joints may be used as a means of attaching the door frame only, without providing the main support. Ideally the mortar joints should be about ½" thick. Drill into the mortar joint a little off center to make sure that the drill bit does not nick the seal or any part of the glass block. Insert a plastic type plug into the drilled hole. Apply a couple beads of sealant to the back of the doorframe just before you screw the frame up against the glass block wall.
Pittsburgh Corning now offers three new complete Shower Systems, two of which include a shower door. Complete instructions are available. See the section on "Shower Systems". Shower doors can be ordered individually.
Can a glass block window be mortared in solid around the frame?
If installing within a masonry type wall (i.e., brick, concrete, etc.) and the panel is 25 square feet or less, the jambs may be mortared solid. At the top we still require an expansion material and sealant. In wood frame walls use Perimeter Channels supplied by Pittsburgh Corning.
If the exterior wall is thicker than the glass block, should the glass block be installed to be flush with the outside, inside, or can it be in the middle?
It does not make any difference as long as the remainder of the opening is framed out and made watertight . . . similar to installing a normal window.
With all the sizes of glass block available, I cannot find any combination of sizes that will fit my opening. Can you help me?
Not all sizes of glass block that are available will necessarily neatly fit all openings. Some adjustments would have to be made to the opening to accommodate an exact fit. Those adjustments can be made by either raising or lowering the sill, or adding or deleting from the framework of the opening.
I have determined that if I install the glass block with spacers, I may not have enough room within my opening to fit my panel. Should I still use the spacers?
Keep in mind that spacers tie you down to a consistent 1/4" thick mortar joint, therefore, the opening must accommodate the panel. By not using spacers and free laying the glass block, you can then adjust the thickness of the mortar joints in the panel to accommodate the opening. Obviously, the larger the panel, the more mortar joints you can adjust the better the fit in the opening.
What are panel anchors?
Panel anchors (Pittsburgh Corning Accessory) are straps of metal that are 1 ¾" wide by 24" long. They are perforated 20 gauge hot-dipped galvanized steel. Each anchor strip is cut in half to create two 12" anchors. They are used to anchor the glass block panel to its surrounding frame in panels larger than 25 square feet. The panel anchors are placed at every other course, up both jambs and across the head section. They are bent 90 degrees to result in a short leg (about 3") and a long leg (about 9"). The short leg is attached to the surrounding frame, and the long leg gets embedded into the mortar joint. You can make two anchors from one panel anchor.
What is expansion strip material?
Expansion strips (Pittsburgh Corning Accessory) are polyethylene materials that are 4" wide by 24" long by 3/8" thick. In the Mortar Two System, they are placed up both jambs (sides) and across the head (top) section between the perimeter glass block and the frame. They provide a degree of movement for the panel and a cushioned surface for the edges of the glass block. They also cover the panel anchors used to anchor the glass block to the surrounding frame. In the Mortar One System they are used only in the top channel. Expansion strips need to be trimmed lengthwise for both Thinline™ and Premiere block. Strip for Thinline™ needs to be cut to 2-1/8", Premiere is cut to 2-3/4".
What is panel reinforcing?
Panel reinforcing (Pittsburgh Corning accessory) consists of two 9 gauge parallel wires with 9 gauge cross-wires spaced at regular (16") intervals. It is placed in every other horizontal mortar joint only (vertical reinforcing is not required). It is placed in the same mortar joint where the panel anchors are located. Reinforcing is used to control mortar shrinkage and provide stability.
How do I install your panel reinforcing in a curved wall?
The innermost parallel wire may be cut periodically and the reinforcing then bent to accommodate the curvature of the wall.
How do you replace a broken glass block?
Apply duct tape to both faces of the glass block and strike both faces with a rubber mallet. The tape causes most of the broken pieces of glass to adhere to it for the protection of the installer. Very carefully chip away the hardened mortar from around the opening being careful not to damage an adjoining glass block. Place the replacement glass block in the opening and push fresh mortar into all four joints from both sides of the panel until the joints are packed solid. Strike the joints smooth and clean.
