Mike,

That sounds reasonable, and was actually my first idea. I mentioned
using a recip saw from below because of the (potential) close
proximity to the kitchen cabinets. I am left-handed and tend to shy
away from circular saws as a result...but I'm sure I can make an
exception in this case.

The joists *average* 16" centers, but that could vary by an inch or
two depending on the joist....and there's no doubt that the
contractors went cheap (and fast). It looks like there's about 1/2"
elevation change over the span of 4'. Levelling compound just won't
cut it (I think).

I checked the rest of the floor, and there are some minor variations
(maybe 1/16" - 1/8" over a 4' span, depending on the direction. I
hope that a levelling compound *will* be able to compensate for this,
but I need to do a bit more research.

There appears to be nothing but 5/8" plywood nailed to the joists. No
other membrane or layer that I can see (so no underlayment).

In terms of stability, should I put another layer of subfloor down
(maybe an extra 3/8" to 1/2")? If so, I guess I should apply a
levelling compound first to correct the minor variations, then add the
plywood, and possibly more compound after that....I think this may get
expensive!!

Cheers,
Dave


Are they at 16" or 24" centers? Sounds like the contractor may have gone
cheap. You may need to either nail extra 2x8's on the side of the existing
boards.

--
Mike D.