floating shelf installation on masonry wall
We recently installed some floating shelves on a concrete block wall using a system I have been wanting to try for some time now and found it worked very well.
In this example the wall is a typical exterior wall for homes in Florida. Concrete block faced with rigid foam plus 3/4″ furring and plaster over gypsum lath. This type of wall can be challenging to attach floating shelves to not because the wall lacks strength but more so because the rigid foam behind the furring will compress under the load exerted by floating shelves.
Normally with our system the tension created by compressive force of the fasteners holding the bracket to the wall keeps the bracket firmly in place.
The relatively low compressive strength of the foam insulation behind the furring in most cases prohibits adequate compressive force needed to secure our bracket with bolts.
Instead, we added 4″ long pieces of 1/2″ steel round rods welded to the back edge of the shelf bracket. The round rods are set in anchoring epoxy directly into the concrete block. We accomplished this by drilling 3/4″ holes at the corresponding locations on the wall to our 1/2″ round rods. The holes pass through the plaster, furring strips, rigid foam, and into the concrete block. We used 3.5″ epoxy screen sleeves inserted into the 3/4″ holes into the block wall.
The sleeves are only 3.5″ and the rods are 4″ which I thought was going to be a problem but it wound up working out fine in this case at least…The holes were a little sloppy in the plaster so the sleeves just recessed into the wall a bit. We then filled the screen sleeves with anchoring epoxyplaced the shelf brackets into the sleeves.
We used some scrap pieces of wood to make legs to prop the brackets in place to sit level so the epoxy would set in that position. When I drilled the holes in the wall, I was thinking the brackets would tilt down because of the size of the holes versus the smaller size of the rods so I drilled with a slight upward angle. I found when we placed the brackets that I had over-compensated or perhaps it wasn’t necessary in the first place because the bracket was tilting up in some places. In those places I simply forced it down using some wood legs wedged between the bracket and the ceiling.
Returning to the jobsite the following day I was even surprised to find how rigid the brackets felt, quite stout.
Looking forward to using this system again.