Installation - Mortar - Mortar Preparation

Mortar Preparation

WHITE PREMIXED GLASS BLOCK MORTAR

The following gives an idea of the number of block that can be installed per 50 pound bag of mortar:

*based on 1/4" mortar joints

• Follow instructions on the premix mortar bag. Be sure to read and understand all precautions outlined by the mortar manufacturer. Freshly mixed mortar may cause skin irritation. Avoid direct contact where possible and wash exposed skin areas promptly with water. If any gets into eyes, rinse immediately with water and seek prompt medical attention. Mixed mortar should be a consistency that will allow it to stick to the edge of the glass block when the block is turned 90°. It's best to test the mortar on the block (Illus. EE), and add water or mortar to the mix as needed.
NOTE: Preparing mortar is an important step. If you have ever laid brick or concrete block, be aware that glass block are nonabsorbent and, accordingly, the mortar must be much less moist. The consistency should be spreadable, but not dry to the point of separating or crumbling. When mixed to its proper consistency, mortar should stick to the edges
of the block when it's turned on edge. Mix what you think you'll use in about an hour.

5.Laying the First Course

• Using the trowel apply approximately a 1/2" mortar bed to the curb or floor.

• Without applying any mortar to the first block, place an "L" spacer at the lower outside corner of the block so that the cross arm will be at the bottom, between the glass block and the curb (Illus. FF). Place a "T" spacer at the other lower corner of the block with the spacer cross arm up (Illus. FF). Slip a 16" long piece of trimmed expansion strip between the block and the jamb, and push the block firmly into place (Illus. FF).

• Slip a "T" spacer between the block and the jamb so that the cross arm is on top of the block.

• Take a second block and apply 3/8" to 1/2" of mortar to the vertical edge that will contact the preceeding block. Position the second block using a "T" spacer on the bottom and a "REGULAR" spacer at the top between the two blocks (with the cross arm down between the blocks). Push the two blocks together (Illus. GG). Follow this procedure for all remaining block in the first course except for the last block. This last block is installed similiar to the first block.

• Take the level and check periodically to ensure that your panel remains level and plumb. In other words, straight, both horizontally and vertically. If you find a problem, adjust the block into place with a rubber mallet before proceeding. While working, take a polyfoam brush to remove excess mortar and fill any voids that exist. Follow this procedure for both sides of your panel.

6. Laying the Remaining Courses

• Apply a 3/8" to 1/2" mortar bed on top of the first course. Be careful to keep the smooth legs of the spacers free of mortar to ensure that the next course of block will sit flat on the spacers.

• To start your next course, place a block (without mortar) against the jambs using spacers that are already in place from the previous course, for alignment. Place a "T" spacer at the upper corner of this block (against the jamb). Install the remaining block in the same manner as you did the first course.

• At this point, remove the previously installed "T" spacers at both jambs at the top of the second course. Apply a 3/8" to 1/2" mortar bed on top of this course.

• Install panel anchors at both jambs by completely embedding them in the mortar and fastening them to the jamb using #12 zinc-plated, one-inch, pan head screws. Use two screws per anchor (Illus. DD). If attatching to tile or masonry, plastic screw anchors should be used. Reinsert the "T" spacers previously removed. Additional mortar may need to be applied to cover the anchor.

• Now it's time to install panel reinforcing. Panel reinforcing is always installed in the same horizontal joints as the panel anchors. Lightly press panel reinforcing into the mortar bed along the entire length of the panel so that it is completely embedded in the mortar. Where more than one reinforcing strip is needed, overlap them six inches (Illus. HH).

NOTE: Panel Anchors and Panel Reinforcing are only installed in every second horizontal course of block. However, they are not required on top of the next to last course of block.

• Proceed with remaining courses as previously described. Remember to install expansion strips along the jambs as you continue.

• As your panel is built, remember to check periodically to ensure that your panel remains level and plumb. In other words, straight, both horizontally and vertically. If you find a problem, adjust the block into place before proceeding. Don't forget to use your polyfoam brush to press squeezed out mortar back into the joints.

• Installing the last course will be different than the previous course in that you will be installing vertical panel anchors. First, twist off the spacer tabs along the top of next to last course on one side of the panel. Then install two blocks, remembering to butter both sides of the second block before installing. Spacers are not required at the top of the panel.

• Install the vertical panel anchor with the long leg facing down (Illus. DD). Completely embed the long leg of the anchor into the vertical mortar joint. Screw the three inch leg of the anchor to the top of the opening. Continue this two block precedure across the final course.

• Install expansion strip across the head. Because the top course meets the expansion strip at the head, no mortar is placed at the top edge of these blocks.

• After installing the final block, be sure to press back into the joints any mortar that has been forced out.

Finishing/Cleanup

• After allowing the mortar to set up for about one hour, twist off the spacer tabs on both sides of the panel (Illus. II).

• Remove excess mortar from the block faces using a damp sponge. Be sure to rinse the sponge frequently. Try not to let any mortar on the block faces dry or set before attempting to remove it. Don't be concerned about the dry film that remains on the block, it will be cleaned off later. Be sure you don't use abrasive materials for this cleanup, since they scratch the glass surfaces.

• Take the striking tool and run it with moderate pressure over all the joints. It is best to strike all the horizontal joints first, then the vertical joints, so that the pattern is uniform (Illus. JJ). Striking removes excess mortar and compacts it to create a smooth, concave, moisture-proof seal. Again, fill any voids that may appear. When you're done with both sides of the panel, all joints should be completely filled with mortar and you'll have a clean, professional-looking job.

• About two to three hours after striking the joints, and once they are dry, you can use a soft, dry cloth to remove the excess film. A common household plastic scouring pad can also be used to clean any excess film.

• Use a white silicone sealant around the perimeter of the panel on both sides. Where curb was used, you'll want to cover it with trim molding. You may also use moldings at the jambs and head (Illus. KK).