When we pulled up the carpet in our 1930's house we can see that there is no "subfloor" The T&G floor is installed directly onto the floor joists. Is this normal?

There are also a couple areas (2 appx 2'x3')that seem to have been cutout and put back in... the wood all matches however the "long boards seem to have been cut for some reason. In a couple of these sections the planks feel a little loose. When you walk on them the bounce a little.

There are also a few small spots were you can see to the basement through small cracks between a couple of boards.

My overall question is Do you think this is normal and we would be able to do a sand and refinish or do you think we need to lay a subfloor and then install new? The floor is definately not level. and has some overall bounce to it. Also any suggestions on how to correct the loose boards if the recomendation is to sand and refinish? We do have full acess from the basement to the underside of the floor.

My friend had this situation in his home and the joists were 24" OC. This meant the tops of some of the grooves were breaking off. It was an old fir floor. I cut off the splintered top of the grooves and glued them back into place.

Then to give the floor strength we installed the subfloor to the back side of the installed fir floor. We cut 22 " strips of 3/4" OSB and used constructions adhesive applied to sandwich the strips. We used short screws to hold the panel in place then scabbed some material onto the joist to tie the panels to the joists as well as the back of the floor.

This fix has worked well. None of the splintered grooves have broken back out.