I'm sure there are lots of ways, many different ways to build floating shelves. There are people on YouTube who come up with creative ways to do pretty much anything and I'm sure building floating shelves is no different. I haven't looked to see what other people have done partly because I've had an idea in my own mind as to how I would do it. But I never had the reason to put my idea to the test, until now. I'm finishing a project for a customer and the last thing to do is to build floating shelves.
I like the idea of doing away with shelf support brackets, but in my own mind I wondered, how do you make the shelves strong enough without the brackets to support a pretty good load. So my idea, which I'm sure is not new or particularly original, is to try to keep the weight down on all the pieces of the shelf but at same time try to give it as much strength to hold typical things that people put on shelves.
So the strength of the shelf is achieved through the way it's internal structure is attached to the wall. Ideally if you hit studs with screws or bolts you're way ahead of the game. If that's not possible then attaching with fasteners that clamp to the back of the sheet rock to hold the structure in place is the next best option. The shell that goes over the structure and provides your finished look for your floating shelf also needs to be as lightweight as possible. Because in doing that you allow more weight to be placed on the shelf and not create a problem with sagging.
So my idea is pretty simple and uses a 1" x 1.5" piece of pine lumber attached to the wall which has suspended off of it 1.5 x 1.5 x 8.25 inch shelf support pieces that are attached with a mortise and tennon type of glue joint. For this video I'm going to show a couple of different ways to attach these pieces and I think either one is plenty strong to do the job.
I had some questions in my own mind as I was doing this as to how strong this really would be and so I did a video last week that I have linked up in the corner that is dedicated completely to checking the strength of this set up. It compares the strength of the glue joints to the strength of sheet rock with toggle bolt types of fasteners and it at least concludes that this type of installation is plenty strong for typical home use floating shelves.
I have been surprised by how solid and versatile this type of installation can really be. I had the misconception that floating shelves were more of a gimmick and not particularly useful in normal use settings, but after working with my own design, I can see how these things can be incredibly strong with a little forethought and planning.
One way to make up this glue joint is to use a festool domino cutter which is by far the fastest way to go. But unless you're in the construction business you're likely not going to have one of these. An equally effective way is to use a dowel. In this case I'm using a 5/8" diameter dowel and drilling through the wall support and the shelf support pieces at the same time by clamping both of them in position. Then the goal is to drill in a straight line. And that part is not necessarily that important as long as the pieces stayed clamped down well while you're drilling.
Once your glue joints have set up, they are ready to install. In this case these are plaster walls so I used toggle bolt style fasteners to secure them to the wall. One of the benefits of installing the floating shelves in corners is that the support structure is significantly stronger just because it's mounted in the corner. However it also creates a challenge because corners are typically never perfectly square. So to get an accurate shape for these corner shelves, I build a template. This method can be used for not only this application but for building countertops or basically any situation where it is difficult to get an accurate shape because simply taking measurements with a tape don't pick up on subtle variations in angles that may be there.
These are strips of 1/8 inch Masonite that are cut to lengths that are needed to create the shape of the shelves. Then with a hot glue gun they are stuck in place. For the upper shelf, the template was really close to being what I needed. However the angle on the corner was just a little tight on the front. So rather than building another template, I just shaved off a little of the front edge and that worked out fine.
The structure of my shelves is pieces of quarter inch plywood that are wrapped with a 2 inch hardwood trim all the way around. In this case I'm using three-quarter inch alder and quarter inch alder plywood. I cut a quarter-inch deep by 3/8 inch wide joint in my hardwood edge that allows the plywood to be glued and nailed in place and then flushes out with the trim. I made my template so that it would be the size of the plywood pieces I needed to cut.