I'm going to be re-tiling our kitchen counter.  I first did it 20 years ago and it now needs to be updated.  We found some nice tiles that go really well with the floor.  As with all renovations, my wife is starting to add ideas to it.
She now wants to get rid of the old sink and put in an undercounter sink.
I'm having a bit of a problem trying to figure out how to do this with tiles.
If I put it totally under the counter (i.e. under the plywood), then the edge of the plywood, backer board and tiles will show. 
I was thinking that I could put the sink above the backer board and only the tiles would go over the sink.  The only thing would be that the edge of the tiles will be exposed..  Plus I would have to make all the cuts perfect so that the opening looks good.  I don't even know if the edge of these sinks are flat enough to fit in the mortar spacing.
Can this be done?
Any advice would be appreciated.
thanks
J

John,

I don't think you'll want any raw edges showing for any of the materials, even the tile. You are going to want to put edge tiles around the sink opening just the same as you will do on the front face of the counter top.

Can it be done? Yes.

Your statement about making all the cuts perfect is an understatement. The first cut that needs to be factored is the opening of the plywood and backer board, with the mortar/tile thickness allotted for. Unless you're extremely lucky with and the sinks' dimensions and the tile widths, you're going to need to cut the widths on four tiles.

Since these sinks have rounded corners, you'll want to get inside corner tiles...which may be 'difficult' at best to obtain. If you don't follow the contour of the sink, it's going to stick out like a sore thumb.

Instead of a bullnose, you may want to consider a tile that wraps completely around a corner.
This WILL require that you angle bevel the corner of the countertop so it has clearance to make the bend.
It's what I had switched to in my shower, after the fact, so it took an extra day and more work before I could install the tiles.
Around a sink it would be very easy to chip bullnose tips with pots n pans, which is why I recommend the wrap around corners instead.

TTUL
Gary

I would save myself a lot of trouble and disappointment with the final product, and go with a sink that sits on top of the tiles. Just my opinion. Explain to the wife that it is not going to look right and she won't be happy with the results if you install the undermount sink. Stack some samples of the materials (plywood, cement board, tile) and show her what the problem will be.

I have just finished replacing our kitchen sink which was tiled over the sink. Removing the tiles is a PITA. I just installed tiles on the spaces where the old tile came from and I put the sink on top of it and it looks better, too.

I was at Home Depot the other day and they have a brochure from a company named Shluter. They make all types of tile accessories. It looks like they have a flexible metal trim that could go around the tiles.
I was planning on putting the sink over the plywood and backer but under the tiles. That way I would only have to hide the tile edges.
I still have decided that I want to do this, but at least I can tell my wife if it will look good.

www.schluter.com
They have an example of an undermount installation.
J

I will say undercounter sinks make keeping the counter top much easier to maintain -- just brush everything into the sink -- no messin' around with dirt and debris under and around the rim of the sink

Is the sink going to be a metal one or porcelain? I'm not too sure that it would make any difference since I have yet to install an undercounter sink. Although I guess the outer edge is going to be fairly thin either way. But if you go with an edge tile like shown above, you may be able to install it under the plywood anyhow. Depending on how much the tile drops over the edge.

We were leaning towards a metal sink, but another type may be an option.
The edge tiles would work but there are very few tiles that have edge tiles like that. Some have bull nose tiles, but I haven't seen very many with edge tiles.
J

John,

My intention in posting that edge tile thing was this: When you tile the countertop you are going to have to do something appropriate with the front edge. Whatever you do there should be appropriate to the edge going into the sink. The sink will be a little trickier because of four inside corners, but otherwise it can be the same.

EDIT --- Talk to the people at a 'real' tile company.  They wouldn't sell many tiles if they didn't have a way to properly edge a countertop.

If I remember-- my old sink was edged with quarter round tile and interior corners. IMO stainless steel sinks are easier to keep looking nice. Admittedly somewhat noisier however.

Not to steal the post here but as Horace/Bill mentioned, steel is easier to keep clean. I did however find that drain cleaner works rather nice on them tough coffee stains in our white"ish" whatever sort of material sink, lol.

One cup of laundry bleach to a sink full of water and allow it to sit for several hours will clean a porcelain sink like new. And we are Hi-jacking this post so Ruggedcashew simply tell your wife it's a "NO CAN DO" .....LOL

Joke: back in the late 70's when hijacking airplanes was at it's peak, a guy came into the cockpit of a DC10 and said: I'm hijacking this plane to Florida, the pilot replied: but this plane is going to Florida, so the hijacker says, Na the last time I got on it went straight to Cuba, I'm just making sure! About the sink countertop, if I had that much trouble with tile, I'd go with real solid rock, granite or marble, but there is a composite countertop I've seen on "Hometime" it's seamless because they use a bonder and clamp the sections together,then sand it to a seamless joint, and they can use a router to cut a bullnose, I don't remember what the stuff is called, but a trip to the "Hometime Website" might help you find it, I know in this economy the housing market is taking a big hit, so remodeling money is tight, but when you can go for the gusto, most times it's the best way to go,but at the same time be frugal where you can be. But in your situation if the tiles aren't working good; you won't be happy with a half-baked result, maybe this is the time to spend a little more for a solid granite or marble, and try to be frugal on other projects.Check out either Hometime or This Old House for the seamless countertop material.Hope this helps, really like the undercounter sink for the cleanliness, my dish drain is slanted backwards and I need to prop it up to let it drain over the sink lip, why they make dishdrains flat is beyond me, more people have sinks with lips, the drains design needs to be re-thought. I have bad water in Florida, it leaves yellow stains everywhere, I tried CLR, but it didn't totally remove the stains, I found a product called Lime-Away, wow that worked, good inside of toilet tank too!P.S. I was talking to my wife about your problem, she had an idea I thought was interesting enough to add, bust up your tile in pieces and jigsaw puzzle them together like a one color mosaic, then when you get to the lip of the counter to the sink the grout lines won't be in straight lines,it just may make it a  stronger and a more durable design due to it being different shaped pieces grouted together.My wife is really my better half.