I am planning to renovate the floor in my living room (about 30 sq.m of floorboards, in fairly rough condition) and since this is a first time for me I would be very grateful for advice/comments/warnings regarding my plan, which is as follows:
1. Lift all the boards (numbering them to maintain placement), removing all nails, tacks etc. and run them through a heavy duty planer-thicknesser, taking around 4mm off each side.
2. Reinforce the joists by gluing and screwing boards to either side of them, then install a 24mm birch plywood subfloor, screwing it to the joists.
3. Lay a thin (3mm) acoustic/insulating underlay.
4. Screw the planed floorboards onto the plywood subfloor in their original positions, leaving a 1-2mm gap between boards (same as current gap), using stainless countersunk screws.
5. Fill gaps between boards with black or brown flexible caulk, to prevent them accumulating crud.
6. When caulk has set, finish-sand and oil the floor.
Further details that may be relevant/useful:
1. I know this will result in a small height change and that's OK.
2. The floor has central heating and water supply pipes under it, so it has to be possible to take it up in the future without causing immense damage or disruption (hence screws and no glue).
3. I don't mind visible screw-heads, as long as they don't stand proud of the floor and create a hazard.
4. I'm a moderately-skilled woodworker/woodturner but have never dealt with flooring before.
Thanks in advance for your input!