Essentially if you build cabinets that are smaller than the space then you can place them and shim them so they sit exactly want them and and then use trim to hide any small gaps.

And the opposite is true for a trim piece (like an end panel). Then you build a little larger and scribe to follow the contours of the floor or wall.

Hope that was clear.

You find wht will be the high spot in the floor along the cabinet run.
Strike a level line alng the walls.
Mark the wall at 34 1/2 above the finished floor height.
Strike a level line on the walls from that.
Layout the cabinet edges on the wall.
Cut 2"-3"wide strips of 3/4" ply.
Starting at the high spot place a strip along the wall, shim and level it. Make sure there are shims at each cabinet joint. Pin thru the board and all shims. Continue till you have a level strip at along the entire run.
Now cut the remaining strips so that they will end up just short of the toe kick
Put one strip at each cabinet joint and level (perpendicularto the wall) again pin em down.
If you did it right you should be able to just dropthecabinets in and screw em to the wall.

I am so glad jakuvall is so generous with his knowledge! A small tip: Splurge on a long level. I bought a 2 m (~78") one, and it made things easy, like getting the cabs on either side of the gap for the DW level.

Hi,
Just wanted to point out that nailed-down strip flooring goes down on subfloor, not 1/4" underlayment. The flooring cleats (the gun-fired fasteners) are precious short as is, and wasting any of their length in underlayment is the best way to get a soft, loose (squeeky) floor installation.
If you are using a glued-down product, disregard.
Casey

I've never done this, even for a single cabinet so please feel free to disregard. It must be very hard to put in cabinets, I spend lots of time just trying to put up a curtain rod!

I saw a video on a cabinet website a while back. The guy says he uses a guide for the uppers so he can hang them alone if needed. He built a box so the top is 18 inches high when the counter is in and I forget how long, but probably at least 18 inches. It was perfectly level on the top and bottom.

Once he has the lowers installed level, he just places the guide on top and sets the upper on it,confirms level, then attaches to the wall. It doesn't move, and his hands are free to use the drill. Plus nobody has to hold it up.

I thought that was pretty clever. I wish I could rememb what site that was, but honestly I have been on so many the past few months for kitchen stuff it is all a blur!

williamsem- that's the way to do it. I use a box that is wide enough for the longest upper and a little deeper than the uppers, box just a tad short of the height I need.
Shorter height makes it easier to shim the wall cabinet plumb, level.
Use a piece of ply for a temporary counter. you can use the box in combination with a cleat on the wall to make life really easy.

Box doesn't have to be pretty- cut material for all sides at once, then to length. When assembling overlap each corner just over the thickness of the next side using that as a guide for square, glue, pin (moves less than screws but keep fingers out of the way), then two screw is plenty.
Then put on the top, doesn't have to be flush with sides can overlap a little- not building furnture here, just a support.

Might as well add this- moldings
Set up a flat surface, at least 3 x 6 feet- if you have floor space for that ok if you have a good back, else use several saw horses.
Cut your longest length first
Do inside corners first
First cut- longest inside- make custs- paint the edged of the cut with your touch up marker-
go over to your flat surface, align your two pieces
put a dab of Titebond Translucent glue (do not use molding glue) white glue also works, rub the pieces together till they start to stick/suck in to each other, carefully align them set them down on the level surface, check the joint, clean excess gently (rest will come off easily later) and walk away to the next run of molding
Come back in 15 minuts and pin the joint- if you have made battens to reinforce the joint in the back glue that in now and pin- now you can locate that piece on top and mark your next one. It is possible if your careful to assemble very large sections before mounting them, but you may want help getting them in the air.

This will give you as good a joint as you can get given the accuracy of your cut and material.
It is much easier to assemble inside joints on the floor than in the air. You only want to be assembling outside joints in the air.
If you are stacking molding- do it one layer at a time- always.

Or, you could simply have the cabinets built with 5" toe kicks.

We're building our base cabs without integral toe kicks...installing leg levelers on the front edge of the cabinet. The back edge of the cabinets rest on a (leveled) 2x4 ledger that is nailed to the studs along the wall. Simple task to tweak the cabs to level by adjust the leveling feet in front.

Toe kicks attach to the levelers with clips.

Hi, we've been busy trying to prepare for cabinets that could be delivered ahead of schedule while we still work full time, so I have not been able to reply individually. Thanks everyone for taking your time to chime in.

Our Thomasville cabinets are not custom made, so we do not have any say in how the boxes are built. I just hope that at the boxes themselves are square, plumb, and level.

Special thanks go to jakuvall for the clear explanations! We might consider investing in EZ-Levels just to speed things up, but what you said about leveling the strips along the wall first and then placing the strips in the front as cabinets are installed makes total sense!

I haven't even gone as far as researching details on how to install moldings correctly, but your tips are noted.

Our kitchen has only three wall cabinets (with 16 base and tall cabinets), so I don't think we'll build a box for them. But we do have a self leveling laser level and I'm planning to install a ledger strip just to make the wall cabinet hanging task a little easy on myself.

And sombreuil_mongrel, thanks so much for the warning about nailed down flooring with the 1/4" ply underlayment. Now, that got me concerned because I do plan on having the floor nailed down (thought it would be faster and less mess than glue down). With our uneven subfloor (in locations pieced together), is there a better way to achieve a uniform evenness across the house before laying down flooring material?

Learning as I go, I kind of did things backwards.

Installing my base cabinets, I found the highest point and put a long ledger board there, with one nail in the very middle. I then leveled it and nailed it in.

To that, I leveled and plumbed my base cabinets. Ta DA!

When installing my uppers, I took an 18" wall cabinet and set it on the counter. I set the uppers on it and screwed them in. I originally used wedged drywall buckets, but that took a lot of finagling.

I'm now going to change the configuration of my base cabinets. I'll do the same thing, just to be on the safe side, with the 18" wall cabinet sitting on them.

It's not that hard, it's just very painstaking. If you have help, I imagine it's 2ce as easy!

I can tell you what not to do, which is what I did. Don't pick a random corner, plop down a cabinet, add the one next to it, then check for level, and repeat.

Turned out that my floor sloped down from left to right, and I started on the right (low) side. Each cabinet I added to the left side was higher than the previous one, so I had to keep pulling out the previous cabs and shimming them higher. It's kind of hilarious if you picture me pulling out first one cabinet, then two, then three.... with the swearing getting louder and longer each time.

About 4 cabinets into the Abbot and Costello routine I came to my senses, checked the entire length of the floor for level, and started over from the left (high) side.

I might as well throw in one useful tip. To check for level along a very long length, lay a board on edge then put your level on top of that. Make sure your board's edges are parallel by measuring the width along multiple points. You can also check your board's edges for flatness by laying it on a known flat surface.

Chiefneil. Oy, I feel for you. I am glad you can laugh about that now!

Hard to find a flat board. To know that you have one, you need to find THREE boards that are flat. You need to compare board A to board B, and B to C, and A to C.

The reason for this is that you could have two boards, one of which is curved convex, and the other is concave. If you hold them up, edge to edge, they can fit hand-in-glove, but neither is flat. However, it is impossible for both of them to match a third board (unless all 3 are flat).

Or you can splurge on a long (2 m) level as I suggested upthread.

I have 4o levels. Ok, maybe just 4, but I have them. Then, I have levels of many shorter sizes, right down to a string level.

How come when I made something level, it still rose up, although the base was ... level.

I think when I'm not looking, level, plumb, and degrees on the tape measure change.

I remember reading somewhere that you can cut long strips off a 4'x8' plywood board and laminate the factory edges together. That will serve as a decent inexpensive straight edge. I have not tried it myself yet.

Yeah, that is true. I use the factory edge of a piece of plywood, for example, to build cutting guides for circular saws.