I can't comment on the subfloor under the cabinets, but I din't think you want them installing cabinets, appliances, etc on brand new finished floors. I think installing cabinets makes sense and then refinish the floors, otherwise they will most likely damage them.

It's a heck of a lot easier to repair damaged floors than it is to repair cabinets damaged by a sander that got away from someone. And, if the GC is doing his job, the floor would be covered with Masonite or something else robust to protect it post refinish. What's typically done is sand, stain, one coat of poly, cover with protector, then install the cabinets and do the final coat of poly once the cabinets are set.

And yes, I'd put plywood--or something more solid than shims--underneath the cabinets. Otherwise, if you've got stone counters, you're going to have an awful lot of weight balanced on 4 small stacks of wood. Kind of like cabinets on stilettos....

Base cabinets should be installed at the same level as the finished floor. Usually this means the finish floor runs under the base cabinets. The only time you CAN"T install base cabinets on top of the finish floor is with a floating floor. In this case, the flooring must be removed (or not installed) in the area of the cabinet footprint. The correct way to raise the subfloor to the same level as the finish floor is to install plywood or cement board underlayment under the cabinet footprint.

Because the flooring in never completely level, base cabinets usually have shims underneath at least one or two corners. Sometimes they are shimmed all around. Shims are part of a cabinet installation, the use of shims is not a problem by itself.

A stack of shims is not acceptable. They may not stay a stack. I use a single shim. If two shims are necessary, some adhesive needs to help them stay in place.

One method I like for ensuring the base cabinet shims will stay in place is to caulk around the perimeter of the cabinet base, before the moulding is installed. This also keeps water from seeping under the base cabinet if you spill, or when mopping. (I caulk again after the base moulding is complete)

kdb-206:

If it were me, I would refinish the floor before installing cabinets, but I'm not going to second-guess what may work for someone else. I wouldn't worry about the drywall mud/dust and wall texture spray.

Installing cabinets with shims is completely proper although I would use the plastic composite types because they snap off easily, they are non-compressive and much more dimensionally stable. I would not worry about moisture seeping through joist cracks and warping cabinets.

I use hot melt adhesive to instantly bond shims in place.

We had our floors refinished (done) before the cabinet installation (starts today). I'm petrified, but thought the alternative would be worse.