We're installing 3cm granite kitchen countertops on existing formica top cabinets. Installer lasered existing top and said there was a dip or rise of 1/4 inch (sorry, can't remember where exactly) and they don't shim that much from the top since granite is heavy and it might crack in 5 years, e.g. I need to disconnect the cabinets and shim from bottom of cabinets to make the tops level and flat. An estimate we got was $1500 to do this. Alot is disconnecting plumbing, pulling the existing counter off and disposing of it, etc. but after playing with it tonight, I can do all that. It's the leveling/flattening I'm asking about, e.g. how do you get the upper surface level and flat for the granite.

I've already removed the formica counter tops leaving the upper edge surfaces of the countertops exposed which the granite will lay on.

Seems like alot of unnecessary work to disconnect and shim cabinets from below and then reconnect them if 1) they don't LOOK unlevel since its only 1/4 inch over 10 feet, and 2) if you can just work with the upper surface of the cabinet edges, either sanding/planing them level and flat at high spotsor adding some material (plastic wood putty/epoxy or whatever) to build up any low spot and then sanding/planing that. Just seems like alot less work that shimming cabinets.

Has anybody done this, e.g. levelled/flattened by working on the top surface of the cabinet edges rather than shimming from the bottom. If so, how do you do it ? And what materials ?

Any advice is much appreciated. The granite is ready and I'm holding up the installation. THANKS.

Bob

 

Where is the 1/4" variance? In the front or in the back or both?

If it's in the back THEY can shim it when the top is installed and dab somesilicone at the shim so it won't come out over time. The tops will probably be set in silicone anyway. If it's in the front....WHERE in the front?

If it's on a juncture of two cabinets it's easy to fix and you don't have to take anything apart probably.

 

Is the low spot near a heavy floor load such as a refridgerator?
If so you may need to jack up the floor from below.

 

Bud, Ken,
Thanks for taking the time to reply. Answer is I don't know yet where they found the 1/4 inch but will call them today, so don't abandon me
I can't jack the floor (should've mentioned its on a slab, not joists so all is sound flooring).
Bud, you mentioned if the dip is at a juncture of cabinets its fixable. I suspect indeed that's where it is as I think it may be two separate cabinets with the sink spanning space between them. Or I suppose if I'm lucky the dip was from a warped formica/masonite (or whatever that stuff is) top which I am successfully removing now and the actual cabinet tops are level.
I gathered from their not wanting to shim that what they are saying is it is preferable to have the distribution of weight of the granite all along the cabinet edges and not just where the shims are.
But I will find out exactly where the dips are (front, back, both)and report back.
I can see now after getting the formica top off that its alot easier now seeing where the cabinet screws are going into the studs if indeed I do have to unhook and shim the cabinets and re-attach. Still though a pain in the arse it seems relative to just fixing any low spots along the cabinet top edges. It still seems crazy to me to shim from below.
By the way, what is the best tool to find dips ? A 10 foot straight edge or level ? Or some kind of laser thingie ? The granite guy had an impressive laser thing with tripod and hand held LCD computer screen. I generally try to use these "Honey-do's" as an opportunity to buy a new "toy" tool, so what should I get (and how do I tell the wife how "essential" it is to a new, beautiful kitchen)...

Thanks again guys,

Bob

 

Do you have any string?

I hate to burst your bubble thinking about the need for a new toy but all you need is a string. Stretch it across the top of the raw cabinets and it will tell you everything you need to know pretty quick. Stretch it along the "long dimension" of the front top rails and then do it again at the back and see what happens.

Exactly correct, this is their goal. You don't want any "point stresses" imposed on the granite underside.

Like I said, the tops will probably be set in silicone anyway so if that is the case the tops will be fully supported once the silicone heals. I can't tell them how to install their product but to do what I suggested is done all the time.