We are having our entire 1st floor hardwooded (prof. installed), but agreed to do all tear out ourselves. We had vinyl in our kitchen, so the underlayment had to be removed. Fun! My husband used a sawzall around the perimeter of the cabinets and in spots cut all the way through the plywood subfloor. He and my neighbor assure me this isn't a big deal. I'm having nightmares about my cabinets sinking down to the basement!!! What do you think?

Cut all the way through the plywood? How long are the cuts that are all the way through? This could be a MAJOR isuue.

in most spots, just 1 -2 inch areas where the blade went too deep.... One area though, is at least 10 inches. I look from the basement at the cut (cut along the front of a diagonal sink base) and there is a joist midway through, so I'm hoping that helps brace it and is not as bad as it seems...

Both he and my neighbor work in new construction and claim bad cuts are made for hvac, plumbing, etc and moved and it's not a problem. I just can't help but wonder if the floor will eventually sag.

Define major issue?

well a 4x10 hole in the subfloor from a vent mistake is an easy fix, put a few long boards over it and that would be fine stability wise (that may have moisture issues though)

But back to your problem, If the cuts are long enough to allow the cabbinets to flex (they may do it now, or could be months before it happens though. And by major problem I mean you may have to remove the cabinets and replace the subfloor. From how you explained it though I would venture to say you can just put some cross bracing up. The 10 dollars in materials, and 20 minutes it would take to brace the 10 inch spot would atleast give you peice of mind, The 1-2 inch spots sound okay, but I have no idea how far apart they are etc. Wouldnt want it to wind up like a perferorated envelope.

My house, Id brace it, its cheap and easy, and will help you not worry about the cabinets sagging

Ex has the answer, in my opinion. Some extra bracing is better than replacing the sub-floor. Easy, fast, In-expensive and the best thing to do.

Well, I'm glad I asked you guys! I'm so happy there's an easy answer. My house is only 4yrs old and I really don't want to tear the cabinets out! I wonder if the flooring guy will say anything to me about this when he comes out to lay the floor....

Anyway, thanks so much! I'm feeling better already. Now we'll see how the actual floor installation turns out!

I concur... use adequate blocking underneath. You should also sister any joist that were cut into, then re-nail the subfloor from the top-side. Thats where using a sawsall will get you in trouble quick.