Cement placer

[knuckle-dragger]

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?

[Evan]

On the off chance the OP is not a troll, the OP should learn how to use cold chisels to properly cut through the concrete block in order to create the desired shape and size of opening needed...

Yet another fabulous example of someone making a mountain out of a mole hill...

Why make a round hole for something in a concrete wall when *I* don't want to pay for someone with the correct size concrete hole saw to come out and make the cut... Surely there is no other way to make a round hole in a concrete block wall other than using an mighty expensive drill bit... Then let me concoct the most "rube goldberg-esque" manner possible to pack mortar into the gaps *I* never should have created in the first place...

~~ Evan

[HeyBub]

Yep. One can rent concrete hole saws in almost any size. They're used for placing floor safes or routing pipes.

Wonder what the OP plans when the fan quits working?

[bob haller]

when the cut from inside is nearly thru the bricks outside will likely spall falling outward..... OP needs exterior access.

better to install just a exhaust outlet with the actual fan somehere else indoors easy to service

[dadiOH]

PVC pipe and a dowel. If dowel is too big - or you are using a big diameter of pipe - whittle down a piece of wood. Good luck with packing mortar into a 1/2" diameter tube. There are also grout bags, look like a cake icing bag. I bought one once, tried it once, threw it away.

I think your nym is appropriate.

[Evan]

[e-mail]:

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

[Evan]

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...

~~ Evan

[gfretwell]

I use a garden trowel. I have a cast aluminum one with a deep curved blade that will shovel in a pretty good amount of concrete at a time.

[HeyBub]

I wouldn't think a fan would do much for a fire rating either...

[aemeijers]

IMHO, this falls into the Life Is Too Short category. For a couple hundred bucks, a concrete cutting company can put a pretty hole through there in an hour, using their honking big drill.

[Evan]

Not true at all, a rated exhaust fan will have a damper inside which can close that is normally held open by fusible links...

You see the same sort of arrangements in some buildings ductwork where the fire compartments must be maintained, at a compartment wall there will be a set of similar dampers inside the ductwork at the boundary...

~~ Evan

[Harry K]

I defy _you_ to use cold chisels and make a neat hole through an existing wall either brick or block.

As for the OP. Without a hole saw you are going to come out with one ugly, ragged, oversized hole.

Harry K

[Harry K]

I doubt it would work for concrete. I once used a caulking gun tube witht he snout cut off to a big hole size for a similar job placing Water Putty to seal cracls in block walls.

Harry K

[knuckle-dragger]

Maybe you should learn to read: It's not concrete block, it's brick. Maybe you should also explain this fantastic skill of properly cutting a round hole: perhaps Evan in a You Tube spectacular!

Your opinion.

You have a better method of packing the mortar? Let's hear it.

[knuckle-dragger]

So... They cost money don't they? More than a cold chisel, mini-sledge, ladder and myself and, I would guess, my rube-goldberg placer.

Same as I do with the other fans: remove the inside grill, unscrew the fan (it fits in the sleeve) and replace as necessary. The sleeve and the flap generally don't go wrong but if they were to I'd cut them out from the inside and replace.

[knuckle-dragger]

Not true. Bricks are strongly held in place.

No. No problem with service.

[knuckle-dragger]

If you only use cold chisels perhaps not however masonry bits drilling a succession of holes around the perimeter help keep it round.

Only by a small amount covered by the outside flange and then with packed-in mortar.

[knuckle-dragger]

Why not have a commercially made one?

You have a point, maybe 1/2 is too small.

Even my wife suggested that but the nozzle is too short. It has to be at least 12 inches long.

Thank you!

[knuckle-dragger]

And there are also expensive hole saw cutters. No one has yet thought about a swinging scaffold.

[knuckle-dragger]

Good idea, That's the sort of thing but in looking at the first couple of dozen Google hits they seem to be only for liquid. No one mentions mortar or anything similar. Further, did you look at the cost? Especially the pneumatic ones. That overpaid contractor is cheap in comparison.

Not necessary.