"Norminn" wrote in message
news:A4CdnSYEw6vuzDDOnZ2dnUVZ_u-

stuff snipped

The old-fashioned trick I've read about is to drive nails at an angle;
usually two on the end of a board are driven at slightly different
angles. Good if you know where the radiant heat is.

Oh so bad if you don't! (-:

I am not sure, but I think we're talking about just re-driving the nails
that have come back up back down again. I get that sense because of the
radiant flooring, which I believe is causing the wood to expand and contract
and is exacerbating the problem. Installation of the radiant heat is
probably the root cause of the flooring trouble because of the
heating/cooling and possible poor installation. It certainly would make me
very hesitant to drive nails or put screws into any place that didn't
already have them. There's nothing quite as annoying as trying to fix one
problem and ending up creating a much bigger one. BT,DT, too. )-:

If the OP is constrained to reusing the same nail holes there are different
types of nails that have much better resistance to loosening than common
nails. If you want extra holding power, go with a ring-shank or screw-shank
nail. Tests show that modified-shank nails hold much better than
smooth-shank nails.

Still, there are still some unanswered questions here, such as WHY the nail
heads are even visible in the first place. As Notbob and others have noted,
the usual method of laying a tongue and groove floor is to conceal the nails
with each course. We also don't know what kind of subfloor they are nailed
into. Or even if they ARE nailed into a subflooring. In my years of
rehabbing fixer-uppers, I've seen stranger. Not much stranger, but
stranger. g

It's amazing the things you can discover if you tell a Realtor to give you
the listings for the ten cheapest properties in an area. That's how I
bought my first fixer upper - it was the best of 10 very, very distressed
houses. VERY distressed.

I believe it was Clare that pointed out that a bad underlayment is going to
continue to pop nails until that problem is fixed. Worse still, is that it
may be practically impossible to fix without pulling up the floor. I agree
with Don, glue is a bad idea that will become obvious when it's time to
refinish the floor. Been there, done that, discovered that glue can "flower
out" along the wood fibers and seriously change the way it takes stain and
other finishes.

Screws were suggested, and they might be a good idea if the substrate will
hold them. If the floors are moving around from the weight of walking
because of a bad underlayment, even screws might even loosen. If that's the
case, I might even consider long countersunk machine screws with washers and
nuts on the other side of the floor at several strategic locations to keep
the substrate and the oak floor from "tectonic" action. (-:

--
Bobby G.