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NewHomeDIYGuy 12-19-2011 09:47 AM

How to build/attach wall hung bathroom vanity
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The next project I have is to create/modify an ikea kitchen cabinet, and make a wall hung bathroom vanity in a small half bathroom. I bought a 30" wide x 24" high x 24" deep refrigerator kitchen wall hung cabinet, and cut the depth of the box down to 21", and the height down to 18". I purchased 2 18"x15" doors from ikea, so I don't have to bother making the doors. I will be having a piece of stone (most likely granite) placed on top of the vanity for a countertop and will be using a vessel sink, so I don't have to cut a large hole in the top of the vanity.

My question is.. how much support is sufficient for the wall hung vanity? I opted to purchase an ikea cabinet, because it comes with nice veneers already attached, which makes less work for me. The "problem" I have with the ikea cabinet is that it's obviously not meant to support the weight of a countertop and sink. It's particle board, so it'll need reinforcing. The width of the opening where the vanity will go is ~31" wide (about 1" wider than the vanity). The plan was to install a 2x4 (or would a 1x3 be sufficient?) under the middle bottom of the vanity (bolted to the studs), and have the vanity rest on that, but should I open up the walls on each side of the vanity, add 2x4 horizontal braces between the studs, and screw the side of the vanity to these new horizontal braces as well?

I found an example of someone who reinforced an ikea cabinet as a bath vanity, and was thinking of doing the same with using plywood to reinforce the cabinet on the inside (ikea cabinets don't come with a wood backing.. ya, definitely kinda crappy):

I'll attach a picture of the space. The vanity will be 11" off the floor.

I'm open to any and all suggestions. Thanks!

NewHomeDIYGuy 12-20-2011 01:25 PM

Anyone have any ideas? I think I'm going to install a 1/2" plywood backing to the ikea cabinet for rigidity, and I'm going to open up the side walls and install horizontal 2x4's. The next question is do you think additional bracing should be added to strengthen the cabinet? Should I focus most of the bracing and support towards the very top of the vanity so the countertop is fully supported and not worry much about the lower parts of the cabinet (since it won't need to hold that much weight)?

Augie Dog 12-20-2011 05:46 PM

I don't know all the particulars of your Ikea cabinet but I have made and installed many floating vanities.

Check out this thread. I hope it helps.

BigJim 12-20-2011 08:11 PM

The unit you posted the picture of is pretty well straight forward and easy to build. You will need to take the door trim off the wall to install it though. If you secure the unit to the back and side walls it should be fine. I do like the way Angie Dog used the metal to install that unit, it should be there til the cows come home.

NewHomeDIYGuy 12-21-2011 08:44 AM

Thanks for the posts guys. I came across that thread regarding the use of rafter ties (I think they're rafter ties..?) and the cleat, but my concern was whether the cabinet was considerably stronger (me starting with an ikea cabinet). The ikea cabinet is just 3/4" particle board, without a backing.

So I've opened up the sidewalls, and will put a horizontal stud between the existing wall studs, and will run two vertical 2x4's vertically to connect it to the floor so it's supported vertically. I'm going to install a 1x3 cleat along the whole back middle of the cabinet underneath the cabinet. Finally, I'm planning on installing 1/2" plywood as the backing for the cabinet to provide rigidity. Now here's where I'm a little unsure of what's really necessary.. Can I just use 3" wood screws to screw the back of the cabinet (1/2" ply) to the studs and 3" screws to screw the sides (3/4" particle board) to the side studs, or should I really reinforce the side of the cabinet like the picture above with 1/2" plywood, and then drive 3.5" screws through the ply and particle board side? Since the sides of the cabinet will carry a lot of the load, I'm concerned about the stress on the screw through the particle board. Am I just over worrying or should I beef up the sides with plywood just to be safe?

Also, I don't quite fully understand how a cleat works. If I install a cleat along the whole bottom of the cabinet, will most of the downward force be transferred on the cleat when someone leans on the countertop? I guess the trick is that the cleat needs to be perfectly flush with the bottom of the cabinet so it supports the load? Finally, if I use a cleat, is screwing the cabinet to the sides through the joist really not supporting the vertical load, but rather holding the cabinet against the wall?

Thanks a lot for the help!

pyper 12-21-2011 09:06 AM

I would have taken a 2x4 and ripped it on a 30 degree angle, then glued and screwed one part of it to the back of the cabinet. The other part I'd screw with 4" screws to the studs. Then the cabinet hangs off the rail.

As long as the joints are good, I think your particle board sides would be plenty strong to hold up the sink, even with someone sitting on the front edge.

You could glue and screw some 1x1 strips along the joints to reinforce them. The important part is where the back joins the sides. If that joint holds, then the sides won't move.

Here's an article on hanging a cabinet with a french cleat:

NewHomeDIYGuy 12-21-2011 10:00 AM


Thanks for the suggestion.. I haven't assembled the cabinet yet, so I could use a cleat on the top of the back, I'm just a little nervous about myself being able to do it properly. I was thinking of a straight cleat along the bottom because it would be easier.

If wood already has a veneer/laminate already on it, will glue adhere to it and provide a strong bond? Using 1x1 strips sounds like a good idea for reinforcing all the joints, and I might opt to do that vs. reinforcing the side of the cabinet with plywood. Since I've already opened up the walls (man I really hate mucking up drywall), I'm definitely going to put studs in the walls and screw the sides of the cabinet into it, even if it's a bit overkill. I'd love for it to be incredibly solid when I'm done w/ it and not have to worry about it. Thanks.

pyper 12-21-2011 10:53 AM

A straight cleat at the bottom will help some, but not as much as at the top.

At the top the weight will bear directly on it. At the bottom, the cabinet will work as a sort of lever, and the weight of the top will cause a rotation.

Without a cleat at the top you will be relying on the extraction resistance of whatever you use to attach the top end. With a cleat at the top you will make use of the shear strength of the fastener.

As far as the veneer, it depends on the quality. If it's got a good glue joint, then glue is stronger than wood. If it's a poor glue joint it will come apart. If you use some screws in addition to the glue, then you'll have a second method of support.

I would think that the sides of the cabinet would be plenty strong enough to hold up the top. If you want to test it, just put your weight on it prior to doing anything. If it takes your weight, it will take the countertop.

The real weak point is the attachment to the wall. You don't want any chance that your fasteners will fail and either tear out of the wall, or tear out of the cabinet.

BigJim 12-21-2011 11:01 AM

You are worrying a little too much over this install IMHO. If you have pipes going through the back of the cabinet the french cleats won't work, you will not be able to slide the unit down with the pipes sticking out of the wall and stick the pipes through the holes.

If you really want to over kill the install, install a cleat on the back wall and side walls and sit the unit on the cleats. To make sure the side cleats can't be seen, just cut the front edge on a 45 angle back under and make the cleat about 1 1/4 inches shorter than the unit. After you sit the unit on the cleats you will need to screw the back and side walls of the cabinet to the studs. Just a word of caution, look where your pipes are and don't put any screws inline with the pipes in the wall, you could hit the pipes using screws that long.

NewHomeDIYGuy 12-21-2011 12:01 PM

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Thanks for the input guys. I opened up the walls (figure I need to run some romex for the wall sconces anyways), and think I'm going to do a cleat all along the bottom (middle and sides), and then just screw the cabinet through the back and sides into the studs. I'll add some studs on the side walls. I'll attach a picture for my current progress..

I guess that should be plenty strong, and I'll just reinforce the top of the cabinet with 1x1's, glued and screwed. Thanks a lot for the advice/help. I definitely over think things and am too anal, which is why things take longer than they should.. *sigh* I need to do more doing and less thinking.. :laughing: Thanks again.

Oh ya, the cabinet is about 1" narrower than the width of the walls (30" vs. 31" wide between side walls), so I can get by without having to remove the door trim, which makes it a little easier. That leaves a bit of a gap on the sides, but I think I'll use something like 2x4 cleats, and that should easily bridge the gap and they shouldn't be visible either.

pyper 12-21-2011 12:38 PM

Shoot -- since you've opened up that much, you could just put two horizontal pieces of wood under the whole thing -- kind of like a bench -- with the "legs" inside the walls.

Or even just one. Cut two 2x4 legs to take the weight, position them inside the two side walls, and use a couple drywall screws to keep them from moving, then set a 2x4 on top that goes from side to side -- a few nails or screws to attach it to the legs.

That would be more than strong enough to hold your cabinet up. I don't know what the shear strength of a 2x4 is, but it's going to be many times more than the weight of your cabinet.

Then you've got the compression strength of the particle board sides to hold the top up. Don't know what that is either, but it should be plenty. You could always reinforce the bottom edge with a 1x4 or something, to spread the load.

NewHomeDIYGuy 12-21-2011 02:44 PM

Thanks pyper for the suggestion. Finished running the electrical wire, and I think I'm going to stick with the original plan (I guess there are a hundred different ways to do it). I would seriously consider making a "bench" like you suggested, but I didn't cut the drywall low enough for the cabinet to sit on it, and I really don't want to have to cut it much lower, as that means more patching I'll have to do. Thanks.

pyper 12-21-2011 03:01 PM

Be sure to post a photo when you're done!

NewHomeDIYGuy 12-28-2011 02:17 PM

3 Attachment(s)
Just wanted to say thanks to everyone for throwing your two cents in. I ended up using a 2x4 clean along the back and the sides, and reinforcing the cabinet as I said above. The thing is very strong, with the exception of the very top piece of 3/4" PB towards the front (where it's unsupported there's some deflection when I lean on it), but I'm going to have a piece of stone sit on top, so it's not a concern.

Anyway, here are the semi-finished pictures. It's not shown in the picture, but I used a handful of 2.5" #10 screws through the back 1/2" plywood into the 3 studs along the back to keep the thing from moving at all. I also painted the side cleats so you don't notice them even if you're looking for them since there's ~.5" gap on each side.

Thanks again for all the help!

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