Things You'll Need
Drill and masonry bit
Mirror brackets and screws
If the mirror is particularly tall and narrow, add a bracket on each side as well. Mirrors wider than 3 feet should have an anchor every 18 inches above and below.
Do not drill into the mortar between blocks. It is far weaker than the blocks themselves, and may crumble.
Concrete block walls provide a unique challenge to hanging mirrors, because you cannot simply nail or screw into them. Instead, you must use specialized expansion anchors, which expand when you insert a screw. This expansion causes the anchor to hold tight to concrete. Once the anchors are in place, the process becomes the same as hanging a mirror on any other wall, though you must use screw-in brackets instead of those with nails.
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Hold the mirror against the wall in the location where you want to hang it. Use a level to ensure that the top of the mirror is perfectly horizontal.
Draw a line along the top and bottom of the mirror with a pencil.
Select plastic expansion anchors that fit the screws included with the mirror mounts. The screws should be able to screw snugly into the anchors.
Drill four holes in the wall with a masonry bit that is slightly smaller than the diameter of the anchor. These holes should be positioned at the four corners of the mirror, 2 inches in from the sides. Drill them on the outsides of the lines so the mirror does not cover them.
Insert expansion anchors into the holes. Tap them with a hammer if required to push them all the way in.
Screw the mirror brackets halfway into the anchors.
Have a partner hold the mirror against the wall while you swivel the brackets over the mirror. Finish tightening them, securing the mirror against the wall.