Sir Topham Hatt wrote:
Hi,
I can't seem to find a definitive answer to this age old question, should a shoe
molding be nailed to the baseboard or to the hardwood floor?

From what I could find out with a Google search, There are 2 theories on this:

1) If you nail it to the floor, no gap will appear between the shoe and the
floor if the floor sags. The downside is, when the hardwood floor expands and
contracts (normal winter, summer movement), it will crack the paint seam between
the shoe and the baseboard

2) If you nail it to the baseboard, the paint seam will not crack when the
hardwood floor expands and contracts, but a gap will appear if the floor sags.

Did I get this right?

Not sure what you read and whether you transcribed it correctly, but I
can tell you that you do not nail shoe molding to the floor. The floor
is meant to expand and contract, and that movement is unavoidable, even
with engineered wood floors. Nailing molding to the floor defeats the
purpose of the expansion space around the perimeter of the floor and
you will see some nasty gaps where you don't want to see them.

Now what's this about a floor sagging? If it sags, you have a bigger
problem than where to attach the molding.

R