I have a cabin that was built in 1930 or so. It has log 'joists', abut 4 inch dia, on 24 in centers. The lengthwise span of these joists is about 8 ft each. Each joist is supported at both ends with a much larger log, approx 8 inch diameter. The log structure seems pretty good from what I can tell. The original flooring on this is 3/4" pine T&G planks, approx 4 to 6 inch width. Anyway, someone installed some Pergo over the top of it and didn't fix the problem with the floor which is some softness in a few places due to the 24 in span, possible damage to the floorboards (moisture issues in the past). What I'm planning to do is to remove the Pergo, and install some underlayment. What I'd like is advice on the underlayment. Should I go with 3/4" plywood or is the 23/32 OSB a suitable choice?
Second question, this is a kitchen area and the base cabinets were installed over the Pergo. Should I remove the base cabinets (this will be a big job I think) or is it OK to remove the Pergo up to the base cabinets and butt the new underlayment right up to the base cabinets?
Third question, is the underlayment even necessary if I install 3/4 finished flooring over the existing flooring (removing the prego of course, but same question about dealing with the base cabinets?
I also have to deal with some transisitons to bedroom and bathroom - is it acceptable to have a small stepdown in these areas or should I be working to keep everything on one level?