Finding hollow cavities in stuccoed concrete block wall


Old 04-25-18, 10:59 AM
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Question Finding hollow cavities in stuccoed concrete block wall

I want to put a portable air conditioner in my garage; it needs a vent hose to the outside. The garage has no windows, so I want to vent the hose thru the concrete block wall. However both sides of the wall are covered with stucco. Is there a reasonable way to find where the hollows in the block are, without drilling a ton of test holes? It's a 5" hose and I would like to put that thru the hollow of one block.
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Old 04-25-18, 11:06 AM
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Welcome to the forums.

At DIY.... there is one thread per topic...... this is yours.

Drill a hole thru the wall and enlarge from there.
If you don't hit the hollow the first time you drill..... move 1" and drill again.

With a 5" hole you may need to chisel out a web anyway depending on a two or three web type block.
Old 04-25-18, 12:41 PM
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Depending on how thick the stucco is, tapping on the block may emit a different sound where the hollow places are.
Avoid block next to windows/doors and corners as they are often filled with concrete.
Old 04-25-18, 12:42 PM
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Are there any recessed electrical outlets on the interior? They will be recessed into a core. From there you can measure in multiples of 16" and should be able to hit a core or be very close, as some blocks are 15-5/8" long. Unless the home is really old and used other than standard length blocks.

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