Evan wrote:

On Aug 31, 4:44*pm, harry wrote:
On Aug 31, 6:24*am, wrote:



I'm trying to put a fan into a 12-inch thick brick wall. Diameter is
about 8 inches. Naturally I don't have an 8 inch masonry bit (and I
wouldn't like to pay the cost) so the next best thing is to cut
through enough bricks to make a squarish hole though which the fan
will fit. But that leaves small gaps on each side which I'd like to
fill in with mortar. I should also mention that I can only get to the
inside; the fan (really the vent part) is lowered from a higher floor
using a string duct-taped in place. When it's where I want it one
strong tug and it's free. So I have to push the mortar in from the
inside and it's a pain in the butt. Push as far as possible using
hands and then use a dowel to push it all the way and hopefully
compact it.

Well there's actually a miniature tool that I could use to do the job.
You know when you have a filling at the dentist: he does his drilling
and then uses a thing that looks like a tube with a piston inside to
place the amalgam in the cavity. He then tamps the amalgam down with
another instrument.

Upsize that tube with a piston to 1/2 inch (or maybe have a range of
sizes from 1/2 to 2 inches), pack it with mortar and then push the
piston home to place the mortar deep into the hole. Now where can I
get such a tool?

Don't use cement, use canned foam to fill the gaps.

That advice is only good if the wall doesn't need to comply with a
fire rating... Otherwise canned foam is not an approved method
of firestopping...

It's also not as strong.