How to Install a Glass-Block Shower

This beautiful bath-improvement project is dedicated to the millions of do-it-yourselfers who’ve always dreamed of building with glass block, but didn’t have the foggiest idea of where to start.That’s right. You can build a gorgeous glass-block shower even if you’ve never laid a single block. It’s all possible with the Glass Block System—a new line of shower kits from Pittsburgh Corning.

Each kit includes an acrylic shower pan, glass blocks, and all the necessary hardware, such as spacers, silicone sealant, anchors and reinforcing wire. The only thing not included is glass-block mortar, which you can buy at any home center or masonry-supply dealer for about $10 per 50-pound bag. Three kit styles are available. The 48-in. square ($2000) and 52-in. neo angle ($2100) both come with a framed glass shower door. The 51 x 72-in. walk-in design that we chose ($2560) has a curved wall and doesn’t need a door. The shower pans come in seven colors and are specifically designed for glass block. For more information, contact Pittsburgh Corning Glass Block, 800 Presque Isle Dr., Pittsburgh, PA 15239; www.pitts burghcorning.com; 800-624-2120.

This project was originally published in the October 2002 issue of Popular Mechanics. You can find more great projects at Popular Mechanics DIY Central.

For our project, we hired a plumber to relocate the shower drain, run new water-supply lines and install the shower pan. Before installing the pan, create a solid base for it by covering the subfloor with 15-pound felt underlayment followed by a 2-in.-thick grid of mortar. With the pan set in place, the mortar will cure to provide solid support. Install the shower pan before the finished wall material (i.e., ceramic tile, solid-surface material, stone).

That way, it will overlap the pan and prevent water from seeping behind. Once the pan is in place, prepare it for the first course of block by roughening the top surface of the curb with 80-grit sandpaper (Photo 1). Sand just enough to remove the gloss, and then wipe the surface clean with a damp cloth. The shower kit comes with slotted metal straps, called panel anchors. The 2 x 24-in. anchors will be embedded in the mortar between the blocks to strengthen the wall and tie it to the shower wall and pan. Bend three anchors to form L-shaped brackets. Make the bends about 8 in. from the ends.

Stand them on the curb with the short legs facing down. Position the first anchor 10 in. from the wall, and the next two 18 in. apart. Mark the positions of two slots in each anchor and bore a 3⁄16-in.-dia. screw pilot hole through the curb at each mark. Stand the anchors back into position and secure each with a single 2-in. screw and washer (Photo 2), but don’t tighten the screws all the way just yet. Mix up a bag of mortar, following the manufacturer’s directions. The consistency should be slightly drier than that used for brick or concrete block. Keep in mind that mortar can be caustic.

If any gets on your skin, immediately wash it off with soap and warm water. While the mortar slakes, prepare a topcoat solution by mixing three parts Weldbond primer (included in the kit) with one part water. Rotate the loosely screwed anchors out of the way. Then, use a foam brush to apply a coat of primer to the top surface of the curb (Photo 3) to help the mortar bond more strongly to it. Turn the panel anchors back into position, and then tighten and drive the screws into the remaining pilot holes. Cover each screwhead with a dab of silicone sealant. While the primer is still tacky, use a small pointed trowel to apply a 3⁄4-in.-thick bed of mortar to the curb (Photo 4). Be sure to cover the metal anchors.

Our walk-in shower is built with 4- and 6-in.-wide straight blocks, curved blocks and rounded end blocks. Before setting the first block, cut a foam expansion strip (supplied) to 27⁄8 in. wide and set it against the wall to fill the joint between the wall and the block. Set the first 4-in.-wide block against the foam strip. Press one of the plastic spacers onto the side of the block near the curb, and tap the block into the mortar (Photo 5). Spread mortar onto both sides of a 6-in. block and slide it between the 4-in. block and the first anchor. Next, apply mortar to the side of another 6-in. block and set it into the mortar (Photo 6).

Add a spacer, and repeat the process until you reach the curved section (Photo 7). Lay the curved blocks with the special curved spacers that come in the kit (Photo 8). Whenever you reach an anchor, apply mortar to each block that flanks it so it will be completely encased in mortar. After setting the fourth curved block, finish the course with an end block (Photo 9). Then, slide plastic spacers into the top of each mortar joint in the first course (Photo 10). Spread a layer of mortar across the top of the first course of blocks and lay the second course. Once it’s completed, insert the spacers and again spread mortar. But, before setting the third course, bend reinforcing wire to the shape of the wall and press it into the mortar (Photo 11).

Trim the end of the expansion strip to the top of the blocks. Then, set the long leg of an anchor into the mortar next to the wall and screw the short leg to the wall (Photo 12). If the screws don’t hit a stud, use plastic screw anchors. Lay a new foam strip on the shower wall over the short leg of the anchor and begin the third course. Note that you must install reinforcing wire, a wall-attached panel anchor and a new expansion strip after every two courses. Continue laying glass blocks (Photo 13). After each course, check the wall with a level to ensure that it’s perfectly plumb. Once the curved wall is five or six courses high, allow the mortar to set up for an hour or two. During that time you can start building the straight glass-block wall at the end of the shower pan (Photo 14). After all 10 courses have been laid, use a 4-ft. level to check the wall for plumb (Photo 15). If necessary, press on the level to push the wall into alignment. Spread a smooth layer of mortar across the top of the wall.

Use the trowel to scrape excess mortar from the walls. Wash all the glass blocks with a wet sponge. Next, twist off the plastic spacer tabs using needle-nose pliers. Fill the resulting holes with mortar, and then strike the joints smooth with a 3⁄8-in.-wide jointer (Photo 16). Allow the mortar to set up for an hour or so. Then, clean the blocks again with a wet sponge, being careful not to pull the mortar out of the joints. When the wall dries, a hazy film will appear. Remove it by buffing with a dry cotton cloth. Fill the joints between the shower walls and the glass-block walls with clear silicone sealent (Photo 17). Smooth out the bead with a plastic spoon or similar object. Wait at least 24 hours before using the shower. Allow the mortar to fully cure for at least seven days, then protect all the mortar joints with the ground sealer included in the kit.