Search the forums

Loading

Where to drill through concrete block?

vandeweg's picture

I'm installing a frost proof hose bib, and need to put a hole through a concrete block foundation. Is it generally better to drill through the block or to drill through the mortar joint?

Thanks,

Mike

(post #93782, reply #1 of 12)

I'd drill right through a core, unless it's one that is filled and has rebar in it. The bit will cut more evenly and predictably that in a mortar joint where you have the different densities and hardness of the mortar and the block.

(post #93782, reply #2 of 12)

I'ld drill thru the vert mortar joint. Why mess with the structural part of the wall?


SamT



"You will do me the justice to remember that I have always strenuously supported the right of every man to his opinion, however different that opinion may be to mine. He who denies to another this right, makes a slave of himself to his present opinion, because he precludes himself the right of changing it."   Thomas Paine


SamT
A Pragmatic Classical Liberal, aka Libertarian.

I'm always right!
Except when I'm not.

(post #93782, reply #3 of 12)

same here....vertical mortar joint (head joint), is easier

(post #93782, reply #4 of 12)

This is probably a trivial issue and maybe not worthy of debate. However, it's raining and I've got a few minutes. I've done this both ways. If this were a 3/8" hole, I'd agree. But in my experience, when I've tried to cut a 1 1/4" hole through a mortar joint, the bit has had a tendency to snag on the harder block which I think is more likely to compromise the integrity of the block. Drilling through the core is smooth and easy. I can't imagine what risk or negative consequence this choice presents. I'm willing to hear any experience to the contrary.

(post #93782, reply #5 of 12)

tried to cut a 1 1/4" hole through a mortar joint, the bit has had a tendency to snag on the harder block


A poured block wall is basically a series of 4"x5" columns and a thin horizontal web.


Hopefully, each column (or every other) has a rebar centered (Riiiiight) in it, and each web has a rebar in it sitting just below the horiz grout line.


The consequences of drilling thru the column is weakening the column (of course) and severing the rebar.  Also, if you hit the rebar with the bit at other than a square, centered angle, there is a good chance of really torqueing the bit. And it takes a long time to drill thru ½" rebar with a concrete bit and it is hard on a hammer drill.


Granted, the RISK of large damage to the struture is minimal 'cuz it's just one concrete column in a row of columns 8" O.C. Might never want to do it underneath a window or door kingstud or other structural column above.


SamT



"You will do me the justice to remember that I have always strenuously supported the right of every man to his opinion, however different that opinion may be to mine. He who denies to another this right, makes a slave of himself to his present opinion, because he precludes himself the right of changing it."   Thomas Paine


SamT
A Pragmatic Classical Liberal, aka Libertarian.

I'm always right!
Except when I'm not.

(post #93782, reply #6 of 12)

Why don't you go through the rim joist?

Beat it to fit / Paint it to match

(post #93782, reply #8 of 12)

there reinforcement wire in the morter joint, go through one side of the center

(post #93782, reply #7 of 12)

Yeah, going through the red-brick veneer and the rim joist is the other option, and drilling through the red brick will certainly be easier than the concrete block. Plus the hose bib will seat up against the flat brick better than it will against the textured blocks that make up the foundation. It's just that it will end up being a little higher than I wanted since the ground near that part of the house drops away, making the rim joists about 4ft off the ground.

I guess at this point the answers have convinced me that there's no overwhelming reason to drill the hole one place or another, so I should just place it based on where it will be easiest to use and easiest to plumb.

Thanks again,

Mike

(post #93782, reply #9 of 12)

drill through vert mortor joint.

(post #93782, reply #10 of 12)

I agree with Tim on this one. I shoot for the face of a hollow cell. If you go for a vertical joint you fight the concrete block all the way through and the soft/hard nature causes the bit to buck and bind. A horizontal joint likely has wire reinforcement and suffers the same soft/hard problem.


Finding a hollow cell is usually easy by tapping with a hammer and listening. Hollow cell - No rebar. I wouldn't worry too much about compromising the structure. The compressive strength of those blocks is impressive. Remember foundation vents are much larger than the hole your drilling. I would be more concerned near corners and in situations where loads are concentrated.


If your a bold sort you can use a ball peen hammer to knock neat holes in hollow cells. A proper whack won't dent a filled cell but a hollow one will yield a nice, neat, 1/2" hole. Tapping around the edge squares up the beveled edge and gives you your needed hole size. Once your through the face you can either drill through the other face or go outside and repeat the procedure. 

(post #93782, reply #11 of 12)

Thanks for the support. Given that I made the qualifier of "unless it's a filled core with rebar in it" and the double challenge of drilling through brick and then wood (and extruded brick is worse to drill than concrete block), this seems to me like the simplest and obvious procedure.

(post #93782, reply #12 of 12)

Let us know how everything pans out. Love to get feedback.