On Mon, 08 Sep 2008 22:40:02 +0100, Rod wrote:

It just feels the right thing to do! I want to be able to drill new
holes anywhere without coming across voids.

But the filler will be so soft compared to brick, block or mortar that the
drill shoot off into it anyway and give you a "problem hole". Stop
worrying about it and deal with the "problem hole" *if* you ever end up
with one.

--
Cheers
Dave.