Glass blocks may be used to add a visual break in a room without reducing the light. They're available in a variety of textures, patterns and sizes but are generally 3 7/8" thick. Their texture is generally applied to the inside, making the outer surface smooth and easy to clean. Materials:
Hammer
Dry-wall nails and screws
Drill, with drill bits and a Phillips driver bit
Water-resistant dry-wall material
1" by 2" wood
Glass blocks
Water-based asphalt emulsion
Glass-block panel anchors
Panel-reinforcing wire stabilizer
Glass-block mortar
Dry-wall screws
Foam expansion strips
Plastic spacers
Notched trowel
Sponge
Scouring pad
Caulk
Striking tool
Safety glasses
Gloves
- Prepare the rough openings before you begin installing blocks. Nail a strip of 1" by 2" wood along the center of the entire opening to support the weight of the blocks (figure A). Attach strips of dry wall on both sides of the 1" by 2" to finish the opening (figure B).
- Apply a coat of a water-based asphalt emulsion to the 1" by 2" wood on the sill of the opening (figure C) to protect the wood from moisture damage. Don't apply the emulsion too close to the edge because the glass blocks will leave a lip, or "reveal," around the perimeter of the opening.
- After you've prepared the openings, you'll install the panel anchors. Bend the panel anchors at a 90-degree angle, 3" from one end. Attach the panels to the jambs at a height equal to that of a stack of three blocks (figure D). You may want to add 1/2" to compensate for the mortar, depending on how much mortar you plan to use. Attach another panel anchor for every third row of blocks. The anchors will help secure the blocks to the jamb.
- Install foam expansion strips around the opening (figure E). These will allow the blocks to expand and contract with temperature changes. In addition, they'll mask the asphalt emulsion on the sill.
- Mix the glass-block mortar. This mortar is made specifically for glass blocks and is drier than regular mortar because glass absorbs no moisture. To test whether the mortar is dry enough, press a handful against the side of a glass block. If the mortar stays in place, it's ready to use.
- Dry-fit a row of the blocks, using plastic spacers (figure F). Cut the spacers for the edge and corner pieces so that the sides against the wall will be flat. When you're comfortable with the way the blocks will fit together, begin laying them with mortar.
- Lay a line of mortar on the sill (figure G), using enough so that it will be squeezed out when you set the blocks in place. Don't apply mortar to the jambs. Set the spacers in place, then set the first glass block in place.
- For the next block, "butter" the side that will be closest to the adjacent block (figure H). Apply enough mortar so that it will squeeze out when you press the block against the first block. Repeat until you have completed the first row of blocks. Check the row for level and plumb.
- Wipe off excess mortar with a damp sponge (figure I).
- For the next row of blocks, lay out a line of mortar that's thicker in the middle than on the sides (figure J). Don't cover the spacers with mortar.
- Set the blocks in place, and insert the spacers. Press the blocks into position. Use a trowel and a damp sponge to clean up excess mortar while it's still damp (figure K).
- Before you begin installing the fourth row, lay a shallow bed of mortar on top of the third row, and lay a panel-reinforcing wire stabilizer in place (figure L). Press the panel anchors into the mortar, and lay more mortar on top (figure M). Set the next row of blocks in place, and repeat the process after every third row of blocks.
- When you reach the top row, continue installing blocks as before. Do not apply mortar to the upper expansion strip.
- After you've finished laying blocks, clean out any excess mortar with a dry scouring pad. Use the curved edge of a striking tool to even out the mortar in the joints (figure N). Strike the vertical joints first, then the horizontal joints.
- Allow the mortar to set for 24 hours, and apply caulk around the edges of the glass-block wall.
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