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Drilling Through Brick Veneer And Cinder Block?

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August 13, 2025, 09:27 AM
4MUL8R
Drilling Through Brick Veneer And Cinder Block?
Looking once more at the ideal path for amateur radio antenna coaxial cable from outside to inside, I believe I should take it through the foundation wall at the garage.

Here, Verizon FiOS drilled through both to put the ONT cable through the wall, so I have a visual guide. But, what is odd here is that the drilling through the mortar on the outside brick veneer does not line up with the mortar of the cinder block. It is off by about one inch.

As it seems best to drill through mortar and not through the "hard" blocks, what's the best practice to go through the typical cinder block and then the brick mortar? Go from both sides?

Is it best to drill a larger hole, perhaps a 3/4 or 1 inch diameter, slip a pipe through that hole, and somehow add a cover disk? I think these are available from typical ham radio sources. If this is best, then it would seem necessary to drill from one side only, and go all the way through so that the pipe hole is straight.

I'm afraid of creating a huge mess in the cinder block, like knocking out an irregular chunk.


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Trying to simplify my life...
August 13, 2025, 09:45 AM
selogic
Drill as small of a pilot hole as you can and then drill the larger hole from both sides . Less chance of knocking out a large chunk.
August 13, 2025, 09:52 AM
YellowJacket
It's not odd at all for the mortar of brick to not line up with the cmu behind it, as there are 3 bricks for every 1 cmu block (8" nominal) in height and 2 bricks for every 1 cmu block (16") in run.

It really doesn't make much difference drilling through mortar or the block. In fact, I usually prefer to drill through the block as it is more stable than the mortar and you can usually get cleaner holes.

A masonry bit in a hammer drill is the best way to go. Also, sometimes it is harder to drive a bigger masonry bit and you can start with a smaller bit and drill a pilot hole to help you.

I would use conduit if you are running line voltage or maybe if you're doing multiple cables or maybe if you expect you'll have to work on the cables or replace them anytime soon. Otherwise, I'd just run a coax straight through, no conduit. I just ran an outdoor wired access point (Cat 5e) to my porch this way last week.



There ain't much difference in the man I want to be and the man that I really am.
August 13, 2025, 09:59 AM
229DAK
I would get some sort of putty to seal up the holes on each end.


_________________________________________________________________________
“A man’s treatment of a dog is no indication of the man’s nature, but his treatment of a cat is. It is the crucial test. None but the humane treat a cat well.”
-- Mark Twain, 1902
August 13, 2025, 10:05 AM
h2oys
Bearing in mind, 3 courses of brick equal 1 course of concrete block.

If you drill through the bed joint, the horizontal one, vs the head joint, the vertical one, they should line up.
August 14, 2025, 07:09 AM
smlsig
quote:
Originally posted by 229DAK:
I would get some sort of putty to seal up the holes on each end.


We’ve used silicone on both ends with great results.


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Eddie

Our Founding Fathers were men who understood that the right thing is not necessarily the written thing. -kkina
August 14, 2025, 09:08 AM
architect
If either wall is exposed to moisture, even just condensation, make sure the hole you drill is not quite horizontal, but with the lower end to the wet side. Does not have to be much of an incline, but every little bit help when keeping water out of the wall. Grommets like these are designed to securely route and seal through-wall installations.
August 14, 2025, 09:19 AM
4MUL8R
Super tips, everyone. One inch ID, good grommets, sloped downward.


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Trying to simplify my life...