HO wants floating shelves built for books and she found this article-18″ HC doors ripped down the middle and nailed to essentially 2×2’s screwed to the joists. I’m saying no way-they will sag (if they even stay up) Just want to get some more feedback to give her-thanks. Jon
http://www.familyhandyman.com/DIY-Projects/Home-Organization/Bookshelves/how-to-build-floating-shelves
Add a strap for easy carrying and pouring when working with 5-gal. buckets.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
I would think it would work
BUT.
The deeper the mounting block (2x3 for instance) screwed to the studs and the tighter the fit, the better.
I would use a drill press (or be damn straight freehand, for the boring through the 2x3-the straighter the better. Countersink the screws so you don't go blind trying to find 5" screws. A structural lag from GRK wouild be ideal. Don't use drywall screws.
What's going to make it sag? I doesn't weigh anything, an all its structure is in the prime bearing locations. It should work out great!
Note that the shelves are only about 9" deep, so not a lot of torque on the mounts unless someone stores their gold bullion on them.
However, the technique used -- a 2x2 cleat fastened to the wall and then the shelf over the cleat -- doesn't provide a lot of support. The glue is doing the lion's share of the work, whereas I'd prefer to see some "fingers" inside the shelf to help transfer the load, along with a stronger connection to the studs than just surface screwing.
I'd say the technique will work so long as the shelves are lightly loaded -- should not be used for books, eg.
For stronger, I'd consider maybe drilling maple dowels (or pieces of 1/4" steel pipe) into the studs, with the dowels extending into the shelves and some sort of piece fitted over them to transfer the load to the inside top of the shelf.
Thanks Everyone-
I appreciate your time. Yes, she does want to put books on them-yikes! I thought of a way to keep them from sagging-glue and nail a hardwood 3/4 x 1 1/2 strip on the faces. As for the mounting....
Jon
This is proven technology
A hollow core door is a torsion box. It has the property of being resistant to flexing both along and across its width. The cantilever method of mounting this torsion box is well proven. It will work, within reason. Much depends on the door's construction, the depth, the load, your screw of choice that holds the 2x2 to the STUDS (not joists), and the method of attaching the door to the 2x2. Without end supports your idea of adding a hardwood strip to the outer edge will do nothing but add weight that will then reduce the load (books, knick-knacks) she can apply to the shelf.
Fine Woodworking magazine did an article years ago (mid 80's) that show a photo of Ian Kirby (no lightweight) sitting on a cantilevered torsion box shelf.
Why re-invent the wheel?
IKEA sells just this type of shelving with metal brackets that have long rods that stick out and slide into recesses in the shelves. They even tell you how much weight they will hold depending on what the metal brackets are screwed to.
"Max. load 11-33 lbs depending on type of wall and fastening."
Available in a variety of finishes, quite attractive and reasonably priced - $20 each. About 43" long.
http://www.ikea.com/us/en/catalog/products/70159100
won't sag
You have a piece of solid wood in front of the shelf and you're attaching to a solid piece of wood in the back only 9" deep? There's no way this will sag. This is essentially a 2" thick shelf, if a 3/4" ply shelf can withstand up to a few feet, then this torsion box will hold for sure. And if I remember from my material's classes, this torsion box is stronger than a solid piece of wood 2" thick.
Make sure the back piece goes the full length of the shelf and fits very snug inside door. IMHO, the easiest point of failure would be between the top skin of the door and the 2x2 on the wall. This needs more than nails. I would put a bead of glue down the full length of the 2x2 (top and bottom wouldn't hurt). The books pushing down on the shelf would work to rip the top layer off the 2x2. You have to make this union very strong. This would unfortunately make the shelves permanent. Hope she likes the idea.
Joe
Thing is, it's not a 2" thick
Thing is, it's not a 2" thick shelf, it's two 1/8" thick pieces of ply and some cardboard that may or may not be well glued.
It is a box
It is a torsion box. The top skin is in tension, the bottom skin, is in compression, and the cardboard or whatever spacers prevent the bottom from buckling.
The moment is always carried by the outer surfaces, even if the wood is solid.
Man, I hate to rain on all you believers but....
Your post said Hollow Core right? ... BOOKS are SUPER HEAVY 25 - 35 lbs / lf ==> +/- 165/235 lbs ... The hollow core door is acting as a unit. I'd be really surprised if Gorilla glue and the best screws in the world would hold this load cantilevered 9" off the wall ... My thought would be to mock it up before you build it for the client. Attaching it to the studs is no issue, it's the rotation off the wall that concerns me. The nailer is going to stay long after the shelf has ripped clear of it. The saving grace in making this detail work MIGHT be gluing and screwing the top and bottom 1/2 rails of the door to the concealed nailer on the wall and then gluing and screwing the doors skins, both sides, to the nailer. The screws probably don't matter much and the whole deal is controlled by the glue. I can't see the nailer being thicker than the door to make your detail work and I don't think you gain anything by going to an 1 3/4" door. Like everyone else said, a tight is fit is critical to developing the strength of the glue joint ... Good Luck!!! Send me pictures of the mock up when it's fully loaded.
BTW, we've done details similar to this for people who really have books, coffee table books, and do the hardwood edge detail but support the shelf from the bottom with deep 8x8 or 10x10 angles screwed into every stud turned up behind the books. Won't work for display shelving but works great for BOOK shelves.
Know my prejudice:
When in doubt, build it stout ... I wish I could tell you how to calculate whether or not this will work ... just my gut feeling ... mock up in your shop.
Good Luck