Floating shelves - attachment methods

[WoodNoob]

Hi all,

 

I'm going to be "renovating" our study and want to put in floating shelves that wrap around the perimeter. See attached pic. 

Well...ideally floating as I like the minimalist look, but if it's crazy, I'll go another route.

 

What are people's preferred method of attaching to the wall? These are plasterboard/stud walls. 

I'm thinking of making the shelves from ply. I've considered something like screwing a thick strip to the wall, with a matching dado in the back edge of the shelf that then gets screws down through the top surface of the shelf into the strip. Make sense? Imagine a pinned mortise and tenon.

 

But I'm not sure how thick or deep that strip would need to be.

The shelves are only going to be about 200mm deep (7.8 in).

 

Any other ideas?

 

[wdwerker]

A 3/4" square strip should do the trick. 1" square is better if you can accomodate it. Shelf needs to be light and stiff, like an airplane wing. Thin skin and ribs, all well glued and either clamped or nailed. Make the pocket for the strip a little extra deep to allow you to scribe the shelf to a wall that isn't very flat. The vertical fit of the pocket to the shelf needs to be slightly snug. Careful accurate craftsmanship is crucial to make floating shelves successful .

[WoodNoob]

Careful accurate craftmanship you say... well I can be careful...

So you're suggesting a torsion box style shelf? I've seen people using pre-made doors for this purpose, but I kind of like the look of exposed edge ply for this kind of thing - But that may be too solid and heavy for what you are saying? Do I make my own ply box that has a many layer ply edge, but only thin sheet top and bottom with struts sandwiched inbetween?

 

My second problem I've just realised, is that if I have these wrap around the walls - how do I slot them onto the strips when the shelves on adjacent walls meet in a mitre?

[wtnhighlander]

Don't use miters if your shelves go full length of the wall on both sides of the corner. There really isn't a way to slip it over the cleat without a gap or break. I suppose you could leave the bottom of the torsion box off, slip the shelf down onto the cleat from above, then glue the bottom on in place, if the structure is light enough to support itself by only the top layer attachment. Of course, you'd have to destroy it to ever take the shelves down.

[wdwerker]

1/4 ply might be too thin unless you aren't going to load the shelves up with books. 3/8 or 1/2 should be plenty. The outside edges could be solid wood or a stack of plywood strips.

Install the backside of a " U" first and work your way to the opening, door, window ,whatever. You could use the same strip/ slot combo at a seam. Butt joint or miter could use this method.

I saw an article where a guy drilled holes barely bigger than a finish nail to attach a mantle to a cleat/ strip. He could pull the nails with a strong magnet and the holes were smaller than a screw. I use trim screws with a #1 square drive head and hide them with those colored wax sticks to match the finish. You can dig it out with an ice pick if you need to remove one. Carefully drilled pilot holes are important !

[WoodNoob]

Thanks guys. I think I'll just have to butt join the shelves in the corners of the rooms, otherwise it'll be too much of a pain to put them on the cleats/strips.

 

Might be a crazy way of doing it, but I'm thinking about around inch thick shelves (laminating two 15mm ply) - routing out an inch deep dado in the back edge for the cleat to fit into. Solid shelf, no need to make a torsion box.  Comments?

[wdwerker]

Might be kinda weak if you make the strip 3/4". A 5/8 strip of a fairly strong hardwood would leave room for a 3/8 thick lip above to hold the screws. If you were going any wider on the shelf the weight will get too heavy to build solid. I build lots of drawers from 5/8 Baltic that's 15mm isn't it? We also build a lot of display parts for a commercial client out of 1/2" Baltic . 1/4 drawer bottoms are standard but when a drawer gets big or we expect a heavy load I go up to 3/8"

That's the beauty of a torsion box strong and light. A 3/8 top , 3/4" framework and a 1/4" bottom would be plenty strong. You could get all your framework strips out of a single sheet of 3/4" (18 mm ?) ribs every 12 to 16" and by insetting the back strip there is no dados to cut. Build the box a tad bit oversize and re rip the front and back to square things up cause assembling a big sandwich like this is never super accurate. I use Titebond liberally and 23 guage micro pin nails. Harbor Freight has a $25 micro pin gun that works pretty good. The pins are headless so put them in at an angle that alternates, this keeps a pin from pulling through until the glue dries.

[wtnhighlander]

Another thing to consider is the amount of leverage applied to the cleat by the weight of the shelf and contents. A thicker shelf spreads the downward force against more wall space, reducing the ratio of downward to outward force applied to the fulcrum point at the top of the cleat. Less force concentrated at that point means less chance of tearing away from the wall.