Instructions for Basement Windows with Glass Blocks

First Row

• 1

  Mix cement mortar according to its manufacturer’s instructions.

• 2

  Place a 1/2-inch bed of mortar on the window sill with a trowel.

• 3

  Place a 16-inch long expansion strip against the side of the window, which is called the window jamb. Set an L-spacer against the expansion strip and into the mortar you laid.

• 4

  Set one glass block into the mortar and against the L-spacer. Set a T-spacer against the bottom corner of that glass block.

• 5

  Put mortar on one side of a different glass block using the trowel. That procedure is called "to butter" or "buttering." Butter the opposite side of that glass block. Set one of the glass block's mortar-covered sides against the T-spacer already in the cement.

• 6

  Repeat the procedure for each glass block in the first row except for the row's final glass block.

• 7

  Place a 16-inch long expansion strip against the jamb. Set an L-spacer against the expansion strip.

• 8

  Put cement onto one side of an unused glass block. Place the block into the last space of the first row with a clean edge against the L-spacer and window jamb.

• 9

  Check the blocks for plumb and level using a level. Tap the blocks into place with a rubber mallet.

• 10

  Fill voids in the mortar, and remove excess mortar, with a 1-inch foam brush.

Subsequent Rows

• 11

  Set T-spacers between glass block and the window jamb, one on each end of the row.

• 12

  Set regular spacers between the remaining glass blocks.

• 13

  Put a 1/2-inch bed of mortar onto the top of each glass block in the first layer.

• 14

  Butter one edge of an unused glass block, and set it with the clean edge against the T-spacer and expansion strip.

• 15

  Butter two opposite edges of a glass block, and set it next to the first block in the row, between the regular spacers. Stop at the second-to-last block.

• 16

  Repeat Step 4 for the last block.

• 17

  Bend a panel anchor by hand into a 90-degree angle.

• 18

  Remove the T-spacers from between the window jambs and the blocks. Set the long end of the anchor on the top of the blocks and the short end against the window jamb.

• 19

  Fasten the short end of the panel anchor to the window jamb with two zinc-covered screws.

• 20

  Repeat Steps 7 through 9 to attach an anchor panel on the opposite side of the window. Replace the T-spacers.

• 21

  Push panel reinforcement into the mortar. Overlap the panels by 6 inches if you need more than one. The panels should be half way into the mortar and not touch the glass blocks.

• 22

  Repeat Steps 1 through 6 to add the remaining rows of blocks. Set expansion strips against the window jambs for every row. Consult the manufacturer’s directions for the correct length of expansion strips.

• 23

  Check the blocks for plumb and level using a level. Tap blocks into place with the rubber mallet. Repeat this step after completing each row.

• 24

  Fill voids in the mortar, and remove excess mortar, with the foam brush. Repeat this step after every row.

• 25

  Stop when you complete the second-to-last row.

Last Row

• 26

  Put all the spacers in place as you did previously.

• 27

  Twist the tabs off the ends of the spacers along the top of the last row of blocks. Use your fingers to twist off the tabs.

• 28

  Set an expansion strip against the window jamb.

• 29

  Butter one side of a block, and set it in the first space with the clean edge against the T-spacer and expansion strip.

• 30

  Butter both sides of the next block, and set it in place.

• 31

  Bend a panel anchor by hand into a 90-degree angle.

• 32

  Slide the long edge of the anchor against the second block and the short end against the window header. Fasten the short end of the ladder to the header with two zinc-covered screws.

• 33

  Repeat Step 5 and add an anchor after every two blocks following Steps 6 and 7.

• 34

  Set an expansion strip against the window jamb.

• 35

  Butter one side of the last block, and set it in place.

• 36

  Set an expansion strip between the last row of blocks and the window header.

• 37

  Check the last row for plumb and level.

• 38

  Remove excess mortar, or fill voids, from the last row as you did previously.

• 39

  Wait one hour. Twist off all the tab ends from the spacers using your fingers. Run a striking tool over all the horizontal joints then the vertical joints. Wipe the blocks off with a sponge dampened in a bucket of water. Rinse the sponge often. Repeat this step on both sides of the window.

• 40

  Wait three hours. Remove film on the glass with a dry cloth or scouring pad.