Floating Vanity Structural Attachment
From contributor M:
It would be nice if you could get in there ahead of the drywall and put a row of blocking where you want to attach them with the strip.
From contributor T:
I'd be losing sleep too. The wall to wall should be okay if you have something to screw to on the sides (I like the "beating the sheetrock man" idea). With the open end, I'd be concerned about the exposed ends. I had a call back that a wall cab was pulling off the wall. Turned out it was the side of the box pulling off the back. That granite is heavy! Will the granite man have a problem with this? They want blocking everywhere, even front to back in 45 corners around here.
From contributor J:
I just installed two of them in a master with concrete tops. Drywall was in, so I couldn't block, so all I could do was use lag screws with fender washers. I'm sure it will hold the weight - I'm more concerned about the cabinets and their ability to hold the cantilever weight, especially with one side open on each. Guess I'll have to wait and see.
From contributor D:
I installed a vanity like this one time, and I lag bolted a piece of steel angle to the studs at the bottom, cut the sheetrock to get the angle iron flat against the studs, set the cabinet on it and screwed through the angle into the cabinet bottom. The top of the cabinet was attached with screws through the back into the studs. I used a 3/4" back that was dadoed and screwed into the sides. The angle iron holds the weight of the cabinet, and the top screws hold it from tipping forward. This cabinet had stone tops and heavy sinks and worked out just fine.
From contributor T:
We have been doing quite a few of these lately. Seems like this year's flavor. We also do frameless - prefinished ply, but instead of our normal dadoed in 1/4" back with 1/2" nailer, I use a 3/4" back, biscuited and pocket screwed to the sides, 2" screws into solid top and bottom.
If they are going to tile the wall first, like in the last one I did (12" X 12" polished granite), work with the tile guy to leave a section out beforehand.
When securing to the side wall, start with a filler, and screw a 3/4" large ply plate to the wall - from back stud to just up behind the filler strip. I have also done some with legs - 2" diameter chrome or stainless steel set back from the front so that they still appear to be floating. Check out the Hafele catalog - they have a few.
From contributor A:
You need to build structural cabinets, not typical kitchen cabinets. All joints need to be glued. Dados if using pre-finished ply to expose some clean wood. Must glue back on. Ideally use 3/4" back. Fastening the cabinet is not the weak link. (6) 1/4" x 4" lag bolts with fender washers should be fine. Most of the frameless cabinets I've seen (i.e. screws no glue) may not take the weight. The key is good glued joints.
From contributor B:
This is not a big issue. I have full tops and 3/4" backs anyway, so nothing different there. I'd put an 8" strip on the wall to the floor as a finished back wall (picks up the vertical weight) or, I think better, a shallow 4" deep box x 8" tall and set the cabinets on that. Some screws to the wall and it will stay, without losing any sleep.
From contributor N:
I have done a few of those vanities. Mounting to the wall is half the battle. Contributor A is right - you have to make sure that the cab is put together for this application. What I usually do on a wall to wall situation is put a cleat on the side that will hold the weight of the top and you can secure the cab to it.
As for open end, I reinforce the cabinet by putting a 1x4 on the top side (inside the cab) with glue and screws. Then I put a 1x4 on the back of the cab and secure it with #10 screws to the studs.
I then put a metal angle bracket on the 2 pieces of 1x4. This will make a strong joint for the side of the cabinet. Make sure you secure the cabinets to the studs. I did a bathroom like that about a year ago and when I went back a couple weeks later to do some touch up, I walked inside the bathroom and saw a painter standing on the vanity (on the open end). When he saw me, he jumped down. I gave him a look and told him not to do that again. He looked like he was about 150-165lbs. I looked at the vanity and it hadn't moved at all! After a test like this, I can sleep at night!
From contributor K:
We have two methods for this...
First method: For 110" wall-to-wall cabinet, because of the granite and live-load weight, I would use decorative fillers on left and right to hide side brackets, and install 8" x 8" steel "L" brackets towards the front on each side of the cabinet, and a minimum of four more along the back, screwed into the wall and underside of the cabinet. Then also screw the sides and back to the wall.
Being that it is wall to wall, I would also tell the client because of the combined weight of the cabinet, granite and contents, you need to open the wall where the cabinet will sit (one coat of spackle patch) to install some support blocking (be sure to charge for this and the extra steel supports). This way you can also control where the side screws can be located (towards the front). When screwing, two at the top (3" apart), two at the middle and two at the bottom (with decorative washers).
You can do the same with the smaller cabs with one side exposed with the same concept... Also, as others have said, cab construction is very important (3/4" construction, screws and glue, preferably dado and rabbet or butt-joint).
Second method: Again, open the wall, create a perimeter between the studs with 2 x 4's where cabinet will be located, as well as 2 x 4 vertical blocking for sides (toward front of cabinet). Cut a piece of 3/4" ply to extend 18" (assuming a 21"-24" depth... adjust accordingly) out from the back of the wall and goes from side-to-side (notch it so it also extends into the wall on the 2 x 4's so you can screw the ply into them). Close the wall with sheetrock, one coat of spackle, place cabinet on ply, screw cabinet sides (near front) and back (with same screw pattern mentioned above along with decorative washers), and a few into the play under the cabinet. You're set to go...
Do either one, and you will have no worries.
From contributor L:
Have the backs come all the way down to the floor. It will still look like a floating vanity. You will still have to make the boxes strong enough to hold the weight of the 3cm top. If they are wall to wall, you can fasten them to the studs on the side also. This should be more than strong enough to hold up the cabinets/tops/humans.
From contributor U:
Plot where you want to attach the cabs, cut the drywall out, discard, block as needed with 2 X, toe or pocket screw into place, pad out as needed or build ledger to accept back base of cabs and install. Next.
From contributor S:
We have had good results y using a metal tee brace that is lagged into the side of the studs and penetrates the sheetrock, 22", at either the bottom of the cabinet (allowing the cabinet to sit on the steel) or at the top of the cabinet sides (allowing the cabinet to be screwed to the steel and have the weight of the top rest directly on the steel).
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