Do Base Cabinets Need Back Shims?

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Shim the front and hang the back, say some. May 4, 2005

Am I a bad installer? I install any kind of cab that makes a buck, all the way up to very high end and commercial. The quality slides on a scale equal to the boxes. I have recently been wondering if there is any reason not to apply one of my shortcuts to all of them. In setting bases, I worry about shim support on the front side only, and lift the hanger rails up level and sock in the screws. This shouldn't be any less substantial than hanging a wall cabinet, should it? Don't wall cabinets usually get the heavy stuff like dishware? Most bases I've seen in use just have the light pans, etc. in them. This trick sure saves a lot of fussing time, but is it an unethical time bomb? Fire away.

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor M:
If the tops are really huge granite pieces or if cabinet is something special for heavy load, you want to shim fully and screw.

For normal situations, if the box is structurally sound and you have support on front, you don't need shims underneath in back. Just make sure you secure to every stud, shimming solidly behind screws. Don't let the cabinet float on a screw that is not backed up and seated firmly. The weight on unsupported screw will make it bend or snap. If it is metal studs, it would be worthwhile to shim underneath or glue to wall plus screws.

Your observation is correct about uppers - that's why we do bases the same when we can.

From contributor W:
I'm with the post above. As long as you know you're getting good solid purchase in the stud behind the base cabinet, I say go ahead and hang 'em.

And keep in mind that a granite counter probably weighs less than 25 lbs a square foot, and since the hanging rail is only supporting half (or less) of the countertop, that means that the hanging rail screws for a 3 foot base cabinet are only carrying about 75 pounds of countertop. And when you think about it, the times you've sat your fat butt on a counter while you worked on an upper cabinet trim detail, you're applying way more weight per sq/ft then a stone counter does.

In my opinion, the difference between a professional and a *seasoned* professional is that the seasoned guy knows when and what to worry about. Spend your time thinking about more important areas... not about whether two or three solidly positioned hanging rail screws are going to carry the day.

From contributor A:
Hanging base cabinets? Shim here or there? You guys are back in the 1950's. Base cabinets have four levelers, four connectors for the next cabinet, and so on. On a run of 6 cabinets, you put a screw on the stud in cab #1 and #6. So simple...

From the original questioner:
Thanks. I love this forum. It's the closest thing to a professional or even fraternal exchange we have. I've learned much from it, even after 25 years of the biz.

You are correct, screws will bend when loaded, even across a short void, so shims do two things. They hold off the wall to level the top, and make a solid connection preventing droop.

Regarding the granite, concrete, cultured crap weight issue, I've installed many a foot of 2x2 wall cleat (as requested by the rock heads) in blind corners, and various open areas. Wouldn't a base cab back rail equal that in resistance to shear?

From the original questioner:
Contributor A, oh, if my world were as simple as yours. Sure, euro boxes are a tribute to techno structo. The factory cabinets I see, though, are mostly face frame style. You can't just horizontal stack them. Commercial custom cabinets come either with levelers, loose ladder style bases, or full height ends. High end kitchens must be scribe fit to funky walls. Also, are your walls perfectly plumb and straight? That would make things simple. Are you punking us?

From contributor J
Also, Euro legs on base cabinets? I thought this was a professional installers' forum? *Real* installers use shims, not crutches (LOL).

From contributor A:
Of course real installers use shims. Real cabinetmakers use levelers and an automatic edgebander, not a manual Virutex. :)

From contributor W:
Leg levelers... now keep in mind that the original question asked about *hanging by the rear rail*.

That said, I'm a huge fan of levelers. My feeling is that on low end work, where you have to get in and get out, they are a bit pricey, but when the budget allows, they're great. When I'm working with a laborer, I get him to put the levelers on the cabinets as I'm laying out the install. But as mentioned, if the base boxes have integral toe kicks, using levelers involves more work, and starts to become less cost efficient.

I personally feel that the savings in aggravation is well worth the small additional cost. Like installing an island. Fasten the island cabs together, lay a level across to the wall cabs, crank the feet until bingo-dead-level.

From the original questioner:
Yet another good idea. It never occurred to me to bring my own levelers to help install. I'm just used to doing what I can with what I get. It still doesn't help with my original question, but it would be sweet for setting a lazy susan base, or an island. Thanks - keep it coming.

From contributor Y:
A box is a box no matter what it pays. Apply your production techniques to those high end installs and spend the time on your crown mitres, which is what most contractors and homeowners look at first. Ethics? Please, just take a look at most GC' and builders today... car salesmen tomorrow! Keep in mind it's a job. Get it done and go on to the next one.

From contributor O:
You call your technique a shortcut, but I call it job security. I sell my installs by telling the potential customers that this is how the "other guy" does it. I not only shim, but many times glue the shims. I don't know... discussions like these get me thinking. I could make more money cutting corners, but I make good on my installs already. I tend to stay away from the fine line between just enough and too little.

Last September we started doing installs for a cabinet company as filler work. By November, their three other installation subs were dismissed and we were doing 90% of their installs plus trying to keep up with our own work. But you're probably right - it is more likely that this is because our trim is perfect than because of how we shim our cabinets.

From the original questioner:

I very much agree with gluing the shims, and if the box is open all around, shimming all four corners is actually the easiest way to go. I can tap and watch the bubble or back mark no problem. Levelers are sweet, but I ain't buying them except for certain needs, since shims don't skeer me. Once done, I make a pencil tic on each shim, go around, and slide them out a little, drop a dab of wood glue on and tap back to the mark. These are allowed to set while I move on, and they will never drift around. I never glue to the floor, cause I may be the chump that has to pull them out some day. Sometime later, I go around with a utility knife and score and snap off all. I only employ the hanger rail deal when it's a pain to access the back corners. As you pros know, it's a good idea to start your install high enough that the back corners of the boxes are up a little, as most floors drop away from the wall. Shim the front up to your laser line, and then you can lift the backs up and hang at level.

From contributor B:
The best way I've found is with continuous ladder bases. Level 'em with an 8' level, use 4" square blocks screwed to the inside kick running to the floor, instead of shims. Glue and hot melt your finished skin or decorative base mold and go home knowing that if the tile guys slam their pallet jack into it, it'll still be 100% intact and level. (Except the finished skin...) Levelers work. But most are plastic. I won't use plastic anything in a wood kitchen. But that's just me.

From contributor T:
I would never hang any cabinet on anything but a French cleat. This way, the weight is evenly distributed along the total length of the hardwood cleat and there is no screw sheer.

As long as the base cabinet is taller than it is deep, there would be no problem. The problem with wall hanging base cabinets is allowing more than 4" off the floor to be able to get under there to clean. 8" would be minimum for this type of application. Also, deeply recessing the base 10" or more gives a nice effect, with no wall hanging required. Just wall bracing. The base must be at least half the depth of the cabinet to be supported, and then you can just use shims and screws to the wall. You can go up a notch with a hidden strip of neon at the bottom for a truly spectacular look, because the saturation of the neon light obliterates the base and it looks like it is floating.

From contributor N:
We use a cleat on the wall that supports the nailer on the back of the cabinet. I saw "hanger rail" and "French cleat", and maybe we're talking about the same thing. We build our cabs with the nailer cleat proud of the sides of the box. We shoot the floor, transfer the level line to the wall, securely screw a continuous cleat to the wall, hang the cabinet on the cleat, shim the front, and screw tight to the wall and then to the floor. Done. Counter is level and the applied toe skin scribes to the floor, and the end panels scribe to the wall.

From the original questioner:
I'd love to have that setup, but I never build 'em, just hang 'em. I could really see some advantage to bringing a stack of 1/2" x 6 x 12 ply scraps and popping them on at the voids under the back rails. With a laser, it would be a quick job and do pretty much the same thing. I will try it.