Kitchen Cabinet Help

Pretty much just match your existing cabinets. when you get new countertop you’ll span the tops with 1×4’s which will smooth out any minute differences. Like you said keep all your face frames the same

-- New Auburn,WI

You should be clamping the new cabinet faceframe to the old, flush out the front and top, Run a level along the top, checking flush and plumb. run the level on the front to check that you continuing a straight as possible. Do this to each box as you add. It is nice if you can clamp a few boxes together and install them as a unit. Try to keep the tops going level. Due to the floor, if you are going up or down hill and don’t shim for it, by the time you add a few more boxes , you will be fitting it. Shim where ever you need so that the box stay lined up as you screw them in. As Scott said the rough top will take care of small discrepancies between the top of the boxes. If need be you can skin the toe kick to hide the shims. Also make sure you have a scribe panel on any ends that meet a wall, if not you will have to make a filler pieces and scribe them.

I am not sure what you mean about the cabinets being lower, sounds like your floor is off and the last guy trimmed to keep the top level, If so you may also have to trim. You will find out when you level the first new box and it ends up high with a gap under the back. In this case I would level the box and see what I had to remove from the front lower or where ever.

As for the 90 degree turn, line up the two faceframe edges to make you corner. Use a square and level to make sure you are coming around plumb and flush on the top. I now build a separate toe kick that I install level, fasten it down and set the boxes on top. (much easier)

Do not use drywall screws, get cabinet screws or buy good quality flat head Philips.