On Aug 31, 12:33*pm, Red Green wrote:
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?

Any concrete/mortar is gonna attack the metal it contacts. My guess is
that's why foundation cutouts have PT wood lining in the opening. Kinda *
makes installation/repair/replacement a tad easier too!

Wrong answer...

A foundation "cut out" isn't necessarily "cut" as it can be designed
into
the pour and framed in when the forms are being put together...

Also, cutouts in foundations used for window and door openings require
framing to attach the door/window to...

As to the issue of the metal fan ducting being attacked by concrete,
there is a simple solution to that problem that involves the creative
use of the waterproof roofing under layment membrane...

Someone also mentioned the OP needing exterior access to prevent
chip out when the hole is made in the wall -- perhaps that is ideal
but not required -- there will be some kind of flashing or trim ring
that
comes with the fan exhaust ducting to conceal the transition between
the duct and the wall...

~~ Evan