I just did this for a bathroom counter that was placed between two walls. I bought a piece of 1/4" thick masonite and cut a piece a little wider than top. Then I used a carpenter's square to check for 90 degree back corners (they were off slightly), so I transferred the angles to the masonite and started to take off small amounts. After about two hours, I got something that was a good fit, with about 1/32" clearance on each side when the back edge was up against the back wall. I took this to the granite counter place and told them to cut it precisely because of the tight fit. They did a pretty good job, but, when I went to install it, it was just slightly oversize and I could only slide it in about half way before it got jammed. I took it back and they used a grinder to shave off less than 1/16" from one side, and they also beveled that edge so that it was undercut except at the very front. The second time it set in perfectly and a tiny bit of caulking made the wall joints perfect.

If you are going to have a backsplash at the back and the sides, you don't have to be as much of a fanatic as I was, but I have the countertop butting directly into the walls, with nothing to conceal the joint, so the intersection had to be tight.

I suggest you take the template you have, and transfer it to something that is one-piece, like masonite, as it will be more reliable for the countertop folks to work with. Or, you could even consider something thicker like 3/4" MDF. Mark the template's top side and which edges are which so they don't get it flipped, and mark on the template if the corners deviate even the slightest from 90 degrees. Tell them to keep the template so you can check it against the countertop when you pick it up. Remember that, if the front width of the counter is less than the back width, you will need to utilize the smaller dimension, because you will probably have to slide it in from the front for the install. Don't think you can somehow rotate a piece of thick countertop into place to compensate for dimensions and angles that are non-uniform. If you do run into trouble getting it in place, the one option you have is to scribe where the top of the countertop will rest against the sheetrock, and use a razor knife and a chisel to take out some sheetrock where it rubs against the side of the countertop.

Wow, thanks for the help. I think I will take your advice and use a 3/4" masomite board so I can simulate the installation. All 3 walls have been tile already and it will not have a bask splash so I cannot fudge the wall.

Also, does the template basically need to have straight lines, or can the top be cut with changes to accommodate out of true tile/wall surfaces?

Good thread! I am also planning to use a remnant for my alcove vanity wall - with no backsplash.

Your template shouldn't have perfectly straight edges if your walls don't. Presuming your fabricator has "real" cutting tools, there won't be a problem with wavy cuts. In our bathrooms, we planned to use a 4" granite backsplash, so the fabricator didn't get out the very fancy, very cool laser measuring stuff. He just measured the space and cut that rectangle. It's amazing how wavy those walls are! Without the granite backsplash it would have been terrible. Contrast this with the kitchen which got the full treatment: a couple of those walls butt up to a wall with no backsplash or a cabinet. The counter meets so perfectly you can't slide a fingernail into the space. It sounds like you need to be somewhere in between "it needs to be perfect" and "a rectangle is fine." Some imperfection will be covered by the wall tile, but not a lot.

We needed to cut a trough in our drywall to allow our kitchen counter to be placed. A little patch-up afterwards covered it up perfectly. IF you need to do this, you can cut directly underneath the last tile and it should be fine.

You're doing it backwards. The counter surface goes in before the tile. You may have issues with water intrusion because of that.

hollysprings, I was planning to do wall tile first too. I wanted the tile to go from the floor, up behind a wall mounted, floating vanity. I was planning to caulk the seam where the counter meets the wall. Why would that create a water issue compared to doing it the other way - if the tile goes in after the counter, you would caulk the seam then as well? One reason why I wanted to do the tile first was so the thickness of the tile would not reduce the depth of my counter surface - it will be 19" which is small to begin with.

mayflower1032:

Caesarstone specifies 1/8" at each wall on page 20 of their fabrication and installation manual. That seems generous to me, especially for such a small top.

I hope you meant 1/4" Masonite, not 3/4".

Here is a link that might be useful: 1/8

trebuchet-
I know you were responding to the OP, but I will mention that, if one is trying for a super tight fit, using something thicker than the 1/4" masonite I used can make a difference in simulating how a thick piece of countertop will fit due to small undulations in the wall that may not be apparent when slipping in a thin piece of masonite. If one is willing to go with a somewhat more generous gap than I was, then the 1/4" thick material is just fine. That Caesarstone spec seems a little overly generous...but easy on the installers.

suzanne-
I agree with you, but, when you are trying to fit a countertop in between two walls that are undulating and/or are not precisely at 90 degrees to the back wall, it can be much harder to get the kind of scribed fit that we all agree is the goal because you can only put it in place by sliding it from the front.

numbersjunkie-
I agree with hollysprings that, in your situation, you want to put the countertop in first. First, it totally simplifies how precise the templating has to be, and makes the countertop install much easier. Second, no matter how well you tile, the tiles will be unlikely to all be in a totally flat line, particularly against the long back wall. This is a function of both your wall not being dead flat, and the variation in even a great tile job. If you apply the tile after the counter is in place, the intersections of the countertop with all the walls will be cleaner looking and result in less caulking. And 18"-19" is sufficient for a counter depth. I don't understand why you think you are giving up anything. If the tile goes in place first, your counter is full depth; if the countertop goes in first, just make it deeper by the thickness of the tile and it will have the same result. As for the sides, the walls are a fixed distance apart; whether the tile goes on first or last you will have the same usable width; you just need to have the countertop cut to the right size for the installation procedure you choose.

I used 3" x 36" balsa wood to build a template. And that was hard to get back in place, and that was able to be flexed around. I think the thick masonite would guarantee it will be able to slide in place. I did not want to build my tile around my vanity. I want to be able to remove it without destroying the tile around it. I have 2 other bathroom using plumbing behind the same vanity. Figured if there was an issue, the vanity could be removed so I could get access to plumbing. In my other bathroom, they tiled in the vanity requiring demo of everything around it to get it out. I was not planning on using a backslash

I used 3" x 36" balsa wood to build a template. And that was hard to get back in place, and that was able to be flexed around. I think the thick masonite would guarantee it will be able to slide in place. I did not want to build my tile around my vanity. I want to be able to remove it without destroying the tile around it. I have 2 other bathroom using plumbing behind the same vanity. Figured if there was an issue, the vanity could be removed so I could get access to plumbing. In my other bathroom, they tiled in the vanity requiring demo of everything around it to get it out. I was not planning on using a backslash

hollysprings, I was planning to do wall tile first too. I wanted the tile to go from the floor, up behind a wall mounted, floating vanity. I was planning to caulk the seam where the counter meets the wall. Why would that create a water issue compared to doing it the other way - if the tile goes in after the counter, you would caulk the seam then as well? One reason why I wanted to do the tile first was so the thickness of the tile would not reduce the depth of my counter surface - it will be 19" which is small to begin with.

Thanks for directing me to the manufacturer site...just learned I cannot attached the sink to the bottom of the countertop (support needs to be independant and cannot use fasterners on the material), need to build a support system. This may be a deal breaker for me for caesarstone. My vanity would not be able to incorporate such a support rail system.

Also not a fan of 1/8" around the walls. Does this stuff expand that much?

mayflower1032:

Use a Hercules Universal Sink Harness from Braxton Bragg. $4.99.

I ignore manufacturer's specifications very carefully, but in this situation there is no problem.

When reviewing your product, I found another. You install brackets on each end and drop in a metal bar which slides each way. It has bolts with flat tops you tighten up under the sink.

With the wire system, strange photo from the manufacturer site...why would you install a bracket to the underside of the counter? In that case, might as well just use the brackets that come with the sink in the first place. Why do they screw into granite to hold sinks... does that hold sinks better than the fake manmade surfaces such as caesarstone?

I have Caesarstone and my sinks are not clamped. I didn't take photos (nuts) but a piece of plywood wood went on top of the vanity, then they cut the sink holes and routed out the edge all the way around so the sink gets recessed in the plywood. The stone went on top of that. The mitered edge of the stone top hides the plywood. My kitchen sink was set the same way and covered with soapstone.

-Babka

"Also not a fan of 1/8" around the walls. Does this stuff expand that much?"

mayflower-
Any clearance around the walls is simply because almost all walls are irregular and cutting the countertop slightly smaller is a way to deal with it. You can have as little clearance as your walls will allow. If you can get a template slid in place, you can get an identical size countertop slid in place. This has nothing to do with "expansion"...that doesn't happen.

Expansion and contraction certainly does happen around countertops, but it's more likely the walls doing the movement than the countertop, especially those with heating seasons.