# new hole for dryer vent in cinder blocks



## gregzoll (Dec 25, 2006)

I would not place it that close to the a/c unit. I would go higher up to the ledger above the cinderblock, than go through the block.


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## RWolff (Jan 27, 2013)

The hole in the corner shouldn't be a problem, and if you honestly had to worry about a 4" hole there causing your house to come down, I'd worry a lot about being there!.
If you can cut the hole out that's best, rather than trying to break it out with a chisel.


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## jobblyman (Sep 15, 2010)

Thanks for the replies. That AC unit is old, seldom used, and will be replaced sooner than later. I feel it's too close to the house to begin with, but it was here long before I was.

The rim joist is a 2 x 10. My understanding is a hole cannot be larger in diameter than 1/3 the size of the joist. For a 2 x 10 I figure that's 3-5/32". A dryer vent is 4", so it's my understanding the hole would be too big. Perhaps that would bring the house down!?

I like the idea of cutting a hole best, I tend to butcher with chisels. Might be best to hire that out to somebody with a large bit than buy one...


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## RWolff (Jan 27, 2013)

jobblyman said:


> Thanks for the replies. That AC unit is old, seldom used, and will be replaced sooner than later. I feel it's too close to the house to begin with, but it was here long before I was.
> 
> The rim joist is a 2 x 10. My understanding is a hole cannot be larger in diameter than 1/3 the size of the joist. For a 2 x 10 I figure that's 3-5/32". A dryer vent is 4", so it's my understanding the hole would be too big. Perhaps that would bring the house down!?
> 
> I like the idea of cutting a hole best, I tend to butcher with chisels. Might be best to hire that out to somebody with a large bit than buy one...


The rim joist is resting fully supported on that block wall, no? the risk of over cutting a JOIST concerns those freespanning across the room, and you don't want to cut the bottoms of those in any way either, but the rim joist if it's supported on the block wall is different.

Keep in mind it takes a lot more than a 4" hole in the wall to "bring a house down"!
This reminds me of a woman who bought several sculptures from me, then afetr she got them she emailed that she thought they were too heavy for her wall so she gave them to a friend for her garden.

I had to write back that the weight of a wall and it's strength is far greater than she thinks, and that a 40# sculpture is NOT going to be too heavy for the wall, the wall holds the roof, snow and more up, 40# is nothing it's another sheet of sheetrock in weight.

Cutting/drilling is better than pounding on the block with a hammer and chisel- that tends to crack the block and can loosen it.


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## stadry (Jun 20, 2009)

why are we talking rim joist when the hole's thru block ? what'd i miss ?

try a 5/8" bit w/bulldog class hammer drill - cheap to rent compared to conc cutter's min charge


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## RWolff (Jan 27, 2013)

itsreallyconc said:


> why are we talking rim joist when the hole's thru block ? what'd i miss ?


Someone suggested going higher up to avoid having to go thru concrete, to which the OP said:



> The rim joist is a 2 x 10. My understanding is a hole cannot be larger in...


Can't always do that without a bunch of elbows to get the vent up in that area under the floor, or using flex vent hose.



> try a 5/8" bit w/bulldog class hammer drill - cheap to rent compared to conc cutter's min charge


Here's all he needs since he is only drilling the one hole thru the block one time, and his vent is sheet metal so a 4" bit should work: $16.99 at Lowes, there's better bits but since this is aone-time job why spend $80 on a better bit.

*Kobalt Carbide-Grit Hole Saw Kit
*Item #: 322704 | Model #: 9228
Cuts Granite/Masonry Yes
4" HoleSaw, Mandrel and Pilot Bit.

Can get the next larger size to be sure, 4-1/8" maybe available, but for under $20 there's a holesaw to do the hole.


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