I'm starting to lean more and more towards the glue side of things (at
least for round 1). Hopefully this holds, this board doesn't take any
abuse (it simply is a faceplate below the door threshold facing
outward). There's really no way for me to clamp it though, so my
thought is to lean a heavy patio paver up against it while the glue
cures for 24/48 hours). I'll just have to find a warm day as this is
in New England and nights are now getting into the upper 30's.


John Gilmer wrote:

I vote for adhesive. The urethane stuff is incredibly strong. Easier
than
using any sort of screw or anchor. Worst case scenario is that if it
fails,
you can still put the screws in later.

Amen!

Old concrete doesn't want to "drill" right and, often, you end up with
oversized holes. Even if he does drill, the belt and suspenders with the
screws and urethane glue together will keep things in place indefinitely.
That type of glue expands while it cures (and it cures by reacting with the
water in the environment). Thus, it's important to have a good amount of
clamping pressure on the joint.

I had some problems with carpet nail strips on a concrete floor. The
original concrete nails weren't put in right as all the nail did was blast a
crater in the concrete. The glue "fixed" the nail the locked the nail
strip in place.