On Nov 6, 4:49*pm, Oren wrote:
On Sat, 6 Nov 2010 13:19:44 -0700 (PDT), Ken Wood
wrote:

I have a patio slab that has moved noticeably due to the swelling clay
ground underneath.

That is the problem or likely so.

I'm thinking of *painting the slab to deter water from penetrating
it.

Not a solution.

Any pitfalls in this?

Waste of money, time and effort.

Any suggestions for the best paint to use?

Nope.

paint will forever peel crack etc from the slab.

you need drainage improvement all around the slab....... dig a ditch
all around a foot lower than the slab and install a french drain... at
least the exercise will do you good