So I put a very large island in a house that has a dip in the floor - where the middle part of the island is maybe 1/4" low than the outside edges.

One side is 4 large base cabinets. One side is 3 uppers. Three uppers means I had to create a base. Reasoning for the uppers is that having another row of base cabinets would have been way too wide and it took about 2k off the cost.

So the install steps were:

  1. Get the tops of the 4 base cabinets lined up and screw them into each other.
  2. Shim front and back to make it level length and width wise.
  3. Add 2x4 blocking inside along the back edge.
  4. Once fully shimmed screw in the back.
  5. Note (learned after a 20 minute u-turn)... Measure the front of the sides length wise (not the front lip) and make sure it is exactly the same as the back of the sides. 1/16" bowing over four cabinets is 1/4"!!
  6. Cut and plane a 2x6 to attach to the back bottom of the base until the three uppers are slightly below the backs of the cabinets.
  7. Cut and plane another 2x6 for the front.
  8. Add 2x4 blocking to the floor to keep corners and 2x6s in place.
  9. Cut and plane the sides and install flush with finished base cabinets.
  10. Run electrical under where uppers will be installed (doing this after all blocking was easiest).
  11. Put uppers on planed back 2x6... Shim them to exact even with back of other side. Screw them into the top of the uppers to top of base.
  12. Once sides are lined up and happy install front 2x6. Screw it into blocking.
  13. Add side panels.
  14. Add corner trim to hide cuts near toe kick.

So the question is... putting 7 big cabinets together in the middle of a dipped floor seemed like an exercise in futility. 50 shims later and planing down to the miniscule details made the project almost 3 days and I was expecting to have it done in a day :). Please share mistakes I made or tricks to make this process faster.

  • Did you check why there is a dip in the floor?
    – crip659
    Oct 24, 2022 at 17:01
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    @crip659 - we had our normal engineer go out and he says that it was a framing issue with the joists in that section of the house. They were too spaced out and there is an Ibeam that runs cross wise that causes a high point. He said that they should have taken that stability into account and made the joists 1/8-1/4 higher knowing load would push them even... they didn't, it has a dip. Was told that pushing it flat wasn't worth it - from the guy who would make $$ doing it. Said it simply was too small a dip and raising it might domino another issue.
    – DMoore
    Oct 24, 2022 at 17:26
  • 3
    I always do custom kicks, make those level and then add the boxes on top. Sometimes you are shimming the kicks but it is generally pretty quick. I've done kicks where the middle of an L bank of cabinets was 2.5" lower than the end of the L. Oct 24, 2022 at 18:58
  • @FreshCodemonger - you use 2x6s for them? Might be a good answer to go over it. A lot of kitchens I could do this with... but the higher end ones where they want big pullouts and trash pullouts I have to use base cabinets for those.
    – DMoore
    Oct 24, 2022 at 19:20
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    Depending on your cabinet supplier, base cabinets can come without kicks. As noted, it’s way easier to build and level one platform (we usually use 3/4 ply, ripped to whatever we want) and simply throw the cabinets on. Raw cabinet ends get a panel; the kick gets a matching skin. With dips, you scribe the skin, but that’s one line/ one cut, not a bunch of planing. Oct 25, 2022 at 3:11

4 Answers 4


Usual practice, as others have said, is to build a frame the cabinets will rest upon (often acting as the "toe kick"; adding to it when not) and level that. Typically this is just 2-by-4s.

A point others didn't mention: Ideally this will want to be scribed to the floor shape, or (more typically) have a face piece which is so scribed. That gives you something that actually touches the floor along the whole length, looking better and keeping dropped things from going under the cabinets. You can find explanations of how to scribe cabinets to an uneven floor or wall on the web, so T won't go into detail here.

If you're not up for dealing with scribing that face board, you may be able to cheat by running a molding along its base to close the gap, flexing it or cutting at angles to follow the floor line. This is one of the reasons baseboards exist; they hide and close the often ugly junction between floors and walls.

  • good answer and upvoted but I had toekicks on half and nothing on the other half. I did pre-level the side I built kicks for. I usually don't do two-sided islands but I will be using another method next time. The way I did it turned out great but took too long.
    – DMoore
    Dec 15, 2022 at 22:07

I am going to give you one method of a simple and fast way to level a large kitchen cabinet island. I will mention though that there are several.

Make sure you have all your island cabinet boxes built. Mark out an accurate location of where you want your island to be. Using tape is a good method. Simplifying the method simply build a large toe kick frame made of ripped down 2x6 to the exact specifications of your toe kick height.

Build your frame in the same manner you would a standard 2x4 wall.

  • 1
    This doesn't explain how anything gets leveled.
    – isherwood
    Nov 3, 2022 at 12:48
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    So ... where's the method?
    – KMJ
    Nov 3, 2022 at 14:46

Spacing of your supports should be no less then 12" on centre and no more then 24"on centre. Your overall size should be the exact size of your premade island boxes. Now you should have something that looks a lot like a standard wall construction and is precise of your premade cabinetry Now using a 6 ft level or a laser position your frame where your tape outline is and level your frame base precisely using cedar shims to build up dips and low spots.

  • 3
    Please see How to Answer and take the tour. I'm not sure why you broke your answer into several, but you should probably revise to combine them and delete the redundant ones.
    – isherwood
    Nov 3, 2022 at 12:49

Use deck screws to tack in place to your floor.
Now simply assemble your island, premade Cabinet boxes on top of your level frame. Resulting in a very solid perfectly level island. This method has been known to save a day off your labour time. One last thing you should do is using your laser or 6 ft level check to make sure you're level with existing base cabinet height. If there is any difference simply adjust your shims until perfectly level before screwing permanently to the floor.

  • Please Edit all of these into your one original answer. You seem to be trying to use Stack Exchange's Q&A format as if it's a forum - that's not how it works.
    – brhans
    Dec 3, 2022 at 14:53

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