Flooring – Is it possible to fit skirting boards with screws into the wall

Most installs I have done we have trimmed around the fireplace. There are several ways to do it. If your fireplace hearth sits on flat ground we try to meet even - which is almost impossible unless you did the floor and hearth all in one install.

Most of the time we trim around the fireplace first and then cut to the trim. This is very very very time consuming because you will potentially have a lot of boards meet the trim and they need to be within 1/32".

An easier way to do this, especially if the hearth material is not as even, is to add a riser then maybe an optional board (or partial board). So you would layout your wood and just get as close as you can to fireplace then nail down the riser around the fireplace. The corners take some work but this is pretty easy. This looks really good if it is brick and you can get (or notch) the riser so its back sits in a mortar line.

And a note on floating - I would probably use a riser. Because you could set the floating wood 1/4 inch from fireplace, giving it a proper gap, and then staple the riser just to the underlying floating wood. It would still be floating then.

If you're staring with raw planks... PLEASE apply the same finish to all surfaces (underside as well as topside). Otherwise, the surface with the lesser finish will tend to absorb/lose moisture much more quickly than the surface with the heavier finish, and the planks will "cup", "bow", and warp with seasonal humidity changes.

Better than starting with raw planks would be starting with tongue-and-groove planks. The tongue/groove joints helps lock each pair of adjacent planks together so they commonly bear the weight of people & furniture. The T&G joint also helps prevent dirt from dropping down between dried/shrunken planks, preventing the joints from closing again in humid weather & causing buckling of the floor. Last, it helps stop breezes from blowing up through the floor from the space below.

It's possible to install the new flooring as a "floating" (not nailed down) floor over foam insulation (mostly for thermal insulation, but there IS a little sound insulation value)... but that's a whole different type of floor and really begs for a completely different approach. If you try to install any resilient insulation under nailed planks, you'll just get "nail pop", where the nails pop up through the surface of the floor and trip you, possibly tearing bare feet. There are completely different materials available (google "pergo") for floating-floor applications.

If it were my floor... I'd leave all the original floor planks in place regardless of condition, and cover them with all new flooring, diagonal or perpendicular to the original planks' direction.

EDIT: ALWAYS allow new flooring to "season" in its destination room for several weeks prior to installation so it's in humidity equilibrium with the room, preferentially always install during the period of highest humidity and make all joints TIGHT, and ALWAYS leave at least 3/4" (18mm) gap around all edges. You'll probably need to remove any existing mopboards/baseboards & trim before flooring, then cover the gap with them after flooring.