Glass block partition walls define space without cutting off light, which helps maintain a sense of openness in the room. Laying glass block doesn’t require special tools or a lot of experience, and the block as well as the materials needed for the project are available at specialty distributors and home centers.
Glass block is an exceptionally fine building material for spas. It transmits light but obscures views, a fine combination for bathing areas.
You can build your wall to any height. Top a low wall with a course of bull nose blocks to give it a finished rounded edge or with flat block to create a shelf. To build a full-height wall, calculate the number of courses of block you’ll have, then frame-in a header to fill the remaining space between the finished block and the ceiling.
Follow these tips [or a successful installation: When laying out your wall, keep in mind that glass block cannot be cut, so measure carefully. Lay-up the wall using plastic spacers set between the blocks. These ensure consistent mortar joints, and they support the weight of the block to prevent the mortar from squeezing out before it sets. Use premixed glass block mortar, available in dry-mix bags, in white and mortar-gray. When mixing the mortar, follow the manufacturer’s directions carefully to achieve the ideal working consistency.
Because of its weight, a glass block wall requires a sturdy foundation. A 4-inch-thick concrete basement floor should be strong enough, but a wood floor may need to be reinforced. Contact the local building department for requirements in your area. Also bear in mind that glass block products and installation techniques vary by manufacturer – ask a glass block retailer or manufacturer for advice about the best products and methods For your project.
The block wall in this project has a sill made of two 2 x 6s cut to the exact Width of the block. This provides a stable base to help resist floor movement and protect the lower courses. The block wall IS secured to an anchor stud In an adjoining wall by means of metal panel anchors. Expansion strips between the two walls allow for movement.
Tools & Materials:
Chalk line; Circular saw; Jigsaw; Paintbrush; Drill; Mixing box; Trowel; Level; Pliers; Jointing tool; Nylon- or natural-bristle brush; Sponge; 2 x 6 lumber; 16d common nails; Water-based asphalt emulsion; Panel anchors; 2 1/2″ drywall screws; Foam expansion strips; Glass block mortar; 8″ glass blocks; 1/4″ T-spacers; Straight, flat board; Reinforcement wire; 16-gauge wire; Caulk or wall trim; Baseboard.
Floor Reinforcement
If necessary, reinforce the floor joists nearest the new wall by installing sister joists and blocking that are the same size as the existing Joists. If the new wall is not aligned with an existing wall stud. add an anchor stud centered at the new wall location. You can install the sill directly over the subfloor or over a suitable floor covering.
Step 1:
Dry-lay the first course of glass block, using a 3/8″ wood spacer between the wall and the first block, and 1/4″ spacers between the remaining blocks, to set the gaps for the mortar joints. Mark the wall position onto the floor, then remove the blocks. Snap chalk lines along the marks to create the sill outline.
Step 2:
Determine the sill thickness based on the size of your baseboard and thickness of the floor covering. Rip 2 x 6 lumber to the width of the block. If the end blocks are shaped, trim the sill pieces to match, using a jigsaw. Fasten the sill to the subfloor and framing below with 16d common nails. Apply asphalt emulsion to the sill, using a paintbrush.
Step 3:
Mark plumb lines on the adjoining wall, straight up from the sides of the sill. Mark the finished height of each course along the lines. Fasten a panel anchor to the anchor stud at the top of every second course, using 2%” drywall screws. Cut expansion strips to size and adhere them to the wall between the anchors.
Step 4:
Mix 
only as much mortar as you can apply in about 30 minutes. Lay a 3/8″-thick mortar bed on the sill, enough for three or four blocks. Set the first block, using 1/4″ T-spacers at the mortar Joint locations (follow the manufacturer’s directions for modifying T-spacers at the bottom and sides of the wall). Do not place mortar between blocks and expansion strips. Butter the trailing edge of each subsequent block with enough mortar to fill the sides of both blocks.
Step 5:
Lay the remainder of the course. If the wall has a corner, work from both ends toward the center, and install the corner piece last Use 1/4″ T-spacers between blocks to maintain proper spacing. Plumb and level each block as you work, then check the entire course, using a flat board and a level. Tap blocks into place using a rubber mallet. Do not strike them with a metal tool.
Step 6:
At the top of the course, fill the joints with mortar, and then lay a 1/4″ bed of mortar for the second course. Lay the block for the second course, checking each block for level and plumb as you work.
Step 7:
Apply a 1/8″ bed of mortar over the second course, then press the panel anchor into the mortar. Repeat this process at each anchor location.
Step 8:
Add reinforcement wire in the same joints as the panel anchors, overlapping the anchors by 6″. Also overlap the wire by 6″ where multiple pieces are needed. At corners, cut the inner rail of the wire, bend the outer rail to follow the corner, then tie the inner rail ends together with 16-gauge wire. Add another 1/4″ mortar bed, then lay the next course of block.
Step 9:
Build
the wall in complete courses, checking the mortar after each course. When it is hard enough to resist light finger pressure (usually within 30 minutes), twist off the T-spacer tabs (inset) and pack mortar in the voids. Then, tool all of the joints with a jointing tool. Remove excess mortar from the glass, using a brush or damp sponge.
Step 10:
Clean the glass block thoroughly, using a wet sponge and rinsing it often. Allow the surface to dry, then remove cloudy residue With a clean, dry cloth. After the mortar has cured for two weeks, apply a sealant. Caulk the seam between the glass block and the adjoining wall, or cover the gap with trim.
Step 11:
Reinstall the flooring, if necessary, then cut baseboard to fit around the sill. If the end of your wall has curved (bullnose) block, wrap the end with three pieces of trim.
