When connecting the glass blocks to a wall it is best to use support straps, as shown in Figure 4.
The support straps should be placed every two rows and extend past the 2nd vertical joint. If the glass block wall does not line up with a stud, the support straps must be properly secured to the backing material using anchors. Most drywall anchors that grip from behind work well on concrete board.
Figure 4 - Using support straps to connect glass blocks to a wall
The compressible fiber material is very important as the glass blocks need to have a means to expand and contract with the changes in temperature within the shower.
I recommend the use of a quality silicone caulking to seal the joint between the glass blocks and the wall.
Installing The Shower Door Frame (Figure 5):
Figure 5 - Installing the shower door frame against the glass blocks
Installing the shower door jam to the glass blocks can be a difficult process and you can easily break a glass block if you do not provide an adequate expansion joint.
A metal channel, best is aluminum, should run from the floor or step to the ceiling, as shown in Figure 5. The channel should be attached at the top and bottom. The size of the channel is dependent on the inside dimension of the door jam of the shower door that you are purchasing. Hence, in order to complete the structural support of the shower door it must be purchased before commencing the glass block installation.
The door jam is then screwed to the metal channel.