Prepping/leveling new cabinets for granite countertop

[Miss Piggy]

We're completely remodeling our kitchen, from the floor up. In a very mustachian way, we've installed the cabinets ourselves. (Yes, we saved money, likely thousands, but to be honest, I'm not sure I'd ever want to do it again.)  I knew the base cabinets needed to be level, but I've only recently learned that if you're installing a granite countertop, they need to be VERY, VERY level. So instead of relying on the old-fashioned "bubble level" we were using, I bought a 360-degree laser level just to make sure. I was almost afraid of the re-work this laser level would point to, but we were pleasantly surprised that for the most part, our cabinets were pretty darn level. We had to make a few minor adjustments.

My question is this: with the laser level, we're sometimes off by maybe a millimeter. Do we need to use our belt sander where it's a tiny bit high, or is it good enough for a granite countertop?

2nd question: how do we secure the shims that are underneath the base cabinets so they stay in place forever? Is that even possible?

[lthenderson]

I think industry standard is that counter tops can be out of level by 1/8 inch but many places will install them up to 1/4" out of level and use shims.

For securing shims on the underneath side, I usually shoot a nail through them and the cabinet.

[index]

You are fine! A contractor would have just used a bubble level. Just use a finish nailer and shoot the shims under the cabinets into the floor. Good job! leveling cabinets can be a pain in a remodel.

[Miss Piggy]

Thank you both!

There's a new tile floor under the cabinets, so we'll try our best to nail the cabinets/shims without hitting the floor. :)

[Jack]

If you want your bubble level to be more accurate precise, use a longer one (or set it on top of a longer object that's known to be straight, flat and true).

Edit: re-reading my post, I realized I made an error. Precision depends on the length. Accuracy depends on how carefully the manufacturer built the bubble chamber (so there aren't uneven bits on the inner surface for the bubble to get caught on as it moves) and how close to parallel with the surface it is mounted within the level's body.

[Miss Piggy]

I agree. Our bubble level is about 4 feet long and seems pretty accurate. The short ones (less than a foot) seem very inaccurate.

[CmFtns]

We used a 6ft bubble level when I did mine but our cabinets had adjustable feet so it was fairly easy to level... we made them very very close to perfect but there were slight inconsistencies... the granite installed just fine.

[Miss Piggy]

We used a 6ft bubble level when I did mine but our cabinets had adjustable feet so it was fairly easy to level... we made them very very close to perfect but there were slight inconsistencies... the granite installed just fine.

Good to know!

[CmFtns]

We used a 6ft bubble level when I did mine but our cabinets had adjustable feet so it was fairly easy to level... we made them very very close to perfect but there were slight inconsistencies... the granite installed just fine.

Good to know!

3cm granite can span up to a 3ft gap with no support so as long as none of your bumps cause granite to span many feet without touching the cabinets then you should be fine... Do you have a long perfectly straight edge you can lay across in multiple directions to see if you will have long spans of unsupported stone.

In designs where part of the countertop is spanning between supports, the length of the span shall be limited to 2'- 0" (600 mm) for ¾" (20 mm) stone thicknesses and 3'- 0" (900 mm) for 1¼" (30 mm) stone thicknesses.

[paddedhat]

I agree. Our bubble level is about 4 feet long and seems pretty accurate. The short ones (less than a foot) seem very inaccurate.

Accuracy and length are no necessarily related, I have used a level that was 8' long and quite expensive, but worthless, since it was way off. This was most likely a result of abuse, since it was owned by a framing contractor who treated tools like a monkey treats coconuts. I have owned several levels for at least 25 years, and they are still dead on. They are also custom made of maple and cherry laminates with stainless steel wear edges, and they are treated like the expensive instruments they are.

 OTOH, just grabbing any 4' level out of a pile at Home Depot can reward you with an accurate tool, or a useless paint stirrer. It all depends if you take the time to check it for accuracy before you buy. It's pretty easy to do. Place the level on a flat surface and look at the bubble. Now lift the level, swing it 180* and place it exactly where it was the first time, the "top" of the level must remain the same, swing don't flip.  If the bubble is exactly where it was the first time (not necessarily level but in the same spot) the level is good. Do the same thing while holding it against a wall. For a more accurate check, hold the level horizontally, tight to a wall. Center the bubble and make a light pencil mark at the left and right side of the top edge. Now swing the level 180* and place it on your marks. The bubble should be dead centered. repeat this test with the level held vertically.

[Miss Piggy]

3cm granite can span up to a 3ft gap with no support so as long as none of your bumps cause granite to span many feet without touching the cabinets then you should be fine... Do you have a long perfectly straight edge you can lay across in multiple directions to see if you will have long spans of unsupported stone.

We've purchased a couple of 2x4s and some other wood that is about as straight as wood can be...but not perfectly straight. Any suggestions? According to the laser level, we're in good shape, but I do like your idea of using a long straight edge.

[CmFtns]

3cm granite can span up to a 3ft gap with no support so as long as none of your bumps cause granite to span many feet without touching the cabinets then you should be fine... Do you have a long perfectly straight edge you can lay across in multiple directions to see if you will have long spans of unsupported stone.

We've purchased a couple of 2x4s and some other wood that is about as straight as wood can be...but not perfectly straight. Any suggestions? According to the laser level, we're in good shape, but I do like your idea of using a long straight edge.

Honestly your granite installer should make sure there isn't a problem with the base cabinets whenever they come to do the measurements and templating. In my case I just took a long straight edge and put it where the granite was going to go then made sure there was no places where the straight edge wasn't right up against the supporting parts of the cabinet.

[Miss Piggy]

That makes sense.

[couponvan]

We installed our own cabinets and had the granite installed by professionals.  They were really funny when they showed up because they asked who installed our cabinets so that they could recommend them to others.

"Um...Us??"

You've probably gone overboard on the leveling and your granite installer will just love you.  If you are installing the granite yourselves, you'd better get about 10 of your strong friends to help you. That stuff is heavy!

Attached is our granite after installation.  I LOVE IT!

[Miss Piggy]

That looks really nice!

Um, no...we'll let the granite installers install the granite. I do have my limits.  ;)

[pdxmonkey]

I installed my cabinets and just used a standard carpenter's level. I shimmed the cabinets as necessary (mostly not necessary) up off the newly self installed tile floor (installed with a tile puck bubble level) before attaching them to the wall. I wasn't aware there are any special requirements for granite, but did want nice level counters, and when my installer came to take measurements he didn't mention anything. Install went fine and granite has been looking good for several years.

[Fishindude]

Sounds like you are probably fine.  I would have just used a good carpenters level 4' or 6'.
Having the tops all "in line" on the same plane, so you get continuous solid bearing is more critical than if you are out of level a little bit from one end to the other.
And shims can be used as suggested above.

For the record, laser levels are not meant for pinpoint accuracy.  The beam of the laser itself is frequently an 1/8" thick.
I build for a living and when we need to be dead nuts accurate, we use an optical transit with cross hairs, not a laser.

[kendallf]

Sounds like you are probably fine.  I would have just used a good carpenters level 4' or 6'.
Having the tops all "in line" on the same plane, so you get continuous solid bearing is more critical than if you are out of level a little bit from one end to the other.
And shims can be used as suggested above.

^bolded bit above.. I installed cabinets and did granite countertops in one of my houses last year.  Biggest thing was getting them flat, especially if you're going to have a seam.  I did actually shim at the back of one corner to get the seam leveled, installers do this frequently.  The places to get picky are around the sink as that's where you're vulnerable to cracks with only 4-6" widths.  I cut the sink hole in place for this reason. 

IMG_20150131_183703969

[Miss Piggy]

Thanks for the input, everyone!

Well, we must have done okay because the guy from the installation company just left our house after templating/measuring, and he said nothing about anything not being level enough. (He lasered the entire kitchen for an hour.) 

The bad news is that we need additional support for the overhang that's going on two sides of our island. Since this will be our only kitchen seating (we also have a formal dining room), we want 15 inches of overhang for barstools. The steel supports they use can support only 12 inches. So now we need to add some sort of legs or other supports on three outer corners. I'm researching options now...the never-ending project. Ugh.

[CmFtns]

Thanks for the input, everyone!

Well, we must have done okay because the guy from the installation company just left our house after templating/measuring, and he said nothing about anything not being level enough. (He lasered the entire kitchen for an hour.) 

The bad news is that we need additional support for the overhang that's going on two sides of our island. Since this will be our only kitchen seating (we also have a formal dining room), we want 15 inches of overhang for barstools. The steel supports they use can support only 12 inches. So now we need to add some sort of legs or other supports on three outer corners. I'm researching options now...the never-ending project. Ugh.

So you need something like this?

pic:

[Miss Piggy]

Yes, something like that...exactly!

I was picturing the legs for sure, but I had not pictured the horizontal "bars" you have  in your pic. Assuming those are not brand-new pictures, do you have your countertop in now, and is it a seating area? Do the horizontal bars hit people's legs, or are they pretty much out of the way?

[CmFtns]

Yes, something like that...exactly!

I was picturing the legs for sure, but I had not pictured the horizontal "bars" you have  in your pic. Assuming those are not brand-new pictures, do you have your countertop in now, and is it a seating area? Do the horizontal bars hit people's legs, or are they pretty much out of the way?

That's just a picture I found on the internet lol... but my parents have an island at their house with a bar across just like that and it has never been a problem. It sticks down like 4" from counter top but there was plenty of room for your legs and I never remember bumping it or anything when using the barstools. I believe most counter tops that have legs in the corners also have the support/decorative bar across. I think I prefer this look over a free-hanging countertop.

Here's another example I found:

[Miss Piggy]

Okay, clearly I need to do some googling--these are nice pics you've found and shared. Thanks!