New construction.  We unfortunately bought enough engineered floating floor (Kahrs) to do entire kitchen and put cabinets on top.  However, cabinet guy said it makes more sense to put cabs in first, and just run flooring up to them, for a few reasons (including keep the floor safe from damage during construction).  Flooring guy of course wants to do flooring first.

I see online it's almost political how strongly people feel one way or the other (flooring or cabinets first).   I don't foresee replacing either in a long time, unless something happens to the floor, but is there a green building rule of thumb by chance?  Everything is pretty nontoxic if that matters.

Floor is going over 2 inches of lightweight concrete with radiant embedded in it -- second floor - so island definitely has to go straight on concrete so it can be bolted down (no radiant under island).

Your last sentence answered your question for you.
If the island is going directly on the concrete, so should the rest of the cabinetry, (keeps your countertops level)
And, yes, I know you can shim up the island to keep things level, but it is simpler not to.
Plus the floating floor will react better without the weight of the cabinets to deal with.

Seems like the green thing to do would be to not waste flooring under the cabinets and either sell the excess on Craig's List or repurpose it.

I thought they had to shim up regardless? Carpenter mentioned using our excess alder (from trim/casing) to do that, and said we needed to - not sure why.

I guess I'd need to get quarter rounds everywhere then - but not a big deal. Do they prevent spills/crumbs from getting under cabinets well enough?

This does seem to be the way to go -- wish it was enough flooring to do a room...other repurpose ideas for engineered flooring?

Also - what are your thoughts with whether we need to glue between boards. It's a click together system and they say we don't and each flooring sub said something different. Can it hurt to glue between boards in a floating system? Distrib said either way should be fine but I like to hear from actual users.

What does the floor manufacturer indicate about gluing their boards? We did not glue ours and have had no issues with seams (been over a year now). I would be concerned it might just add to expense of installation if the mfg does not recommend it.

they said we don't need to glue them together

I would not glue a click-lock floating floor. The individual boards will move, sometimes at different rates. Glue could cause problems. Plus it is not necessary.
Sorry about the confusion on the term 'shim'. Should have said 'raise the cabinets'. You will normally have to use shims to get the cabinets as level as possible. I used the term 'shim' simply to mean raising the cabinets. I sometimes forget that our colloquialisms don't work outside our local areas.

woksawi
i have installed literally 100's of kitchen's , bath's and 99% of the time they were installed on the subfloor

fwiw

Here in the Mid Atlantic, cabinets are generally installed on top of floors when they are "nail-down".  Not sure of floating.  Reasons for placing on top are more difficulty in installing/replacing a dishwasher if placed on subfloor due to the floor thickness, and getting a proper match-up when replacing cabinets in future years.  Cabinets can rearranged to new configuration and floor can be resanded to eliminate any mismatch.

I have also found it simpler to lay the floor.  The cabinet overhang makes it more difficult to nail.

Correction "lay the fllor first".

Also, you can drill and lag the island through the floating floor, No?

Doesn't really float when you drill and lag through it.

We lay down plywood of matching thickness where the cabinets are to be, to serve as a base to shim and install off of. Install floating floor, then install cabs hiding the floor edge just inside the cabinet base. Eliminates the pain and look of quarter round, maintains perimeter floor spacing and makes flooring install much easier and maintains the "float" for the floor.

Posted By greentree on 18 Dec 2011 11:38 AM
Doesn't really float when you drill and lag through it.

We lay down plywood of matching thickness where the cabinets are to be, to serve as a base to shim and install off of. Install floating floor, then install cabs hiding the floor edge just inside the cabinet base. Eliminates the pain and look of quarter round, maintains perimeter floor spacing and makes flooring install much easier and maintains the "float" for the floor.

Same here, but I install cement board in the whole kitchen area, then cement board under the cabinets to make them level with the finished tile.  If going with manufactured wood/tile, read the manufacturers instructions for potentially wet areas.  Many recommend putting a thin layer of glue on the top of the tongue.  This seals the board to prevent water intrusion.  The floor will still float.  It doesn't matter if they are glued together.  Whatever you do make sure you have something to bring the level of the dishwasher to the same level of the finished floor.  If it starts to leak, you want to know right away.  Also, if you ever decide to change your flooring (before you change your cabinets), it'll be easier to pull up the flooring if you don't have it running under your cabinets.

Sean