Glass Block Windows Installation

Combine glass block mortar and water in a bucket, using the mortar manufacturer's recommended ratio. Stir the glass block mortar with a trowel until it has a smooth gelatin-like consistency.

Dampen the glass block window's opening with water. The water helps the block mortar bond with the opening.

Place a 1/2-inch-thick bed of glass block mortar across the bottom of the glass block window's opening, using the trowel to spread the mortar.

Fill the concave edge on the sides of the glass block with glass block mortar, using the trowel to press the mortar into the block's recess. Set the glass block on the opening's mortar bed. Set all of the first row's glass blocks on the mortar bed, using the same method.

Adjust the width of the mortar joints between each glass block, using a glass block spacer as a placement guide.

Hold a bubble level on top of the first row of glass block. Adjust the top of the glass blocks for level, using the bubble level as a guide.

Hold the bubble level against the outside edge of the first row of glass block. Adjust the first row of block for plumb, using the bubble level as a guide.

Fill the vertical mortar joints on the window's first glass block row with the glass block mortar, using a tuck-pointing trowel to push the mortar into the joints.

Slip a glass block spacer into each vertical mortar joint. Cover the top of the glass block window's first row with a 3/8-inch-thick layer of glass block mortar.

Coat the sides of a glass block and set the block into the window's spacers. Repeat this for each block in the second row. The spacers keep the glass block level and plumb. Fill each of the second row's vertical mortar joints with the glass block mortar, using the tuck-pointing trowel to push the mortar into the joint. Push a spacer into each vertical joint and cover the top of the second row with a 3/8-inch-thick layer of mortar.

Set the remaining glass blocks in the window using the same method used to install the second row.

Clean the excess glass block mortar from the window, using a sponge to wipe the block's face. Let the mortar dry for 60 minutes before continuing.

Twist a glass block spacer's tab until the spacer releases the tab, using a hand to turn the tab in either direction. Repeat this for each tab.

Grout the exterior side of the glass block window with the glass block mortar, using a grout float to force the mortar into the joints. Clean the excess mortar from the exterior of the window with a clean sponge, working from the top of the window toward the bottom.

Grout the interior side of the glass block window with the glass block mortar, using the grout float to apply the mortar. Clean the leftover mortar from the interior side of the window with the sponge, working from the top toward the bottom. Let the mortar dry for 30 minutes.

Wash the mortar haze from the glass block's surface with a clean sponge. Rinse the sponge repeatedly.