exteriorholewalls
I noticed a good sized hole in an exterior wall that allows wires and things to go from my AC unit into my basement.
The problem is that the hole is a good deal larger than it needs to be and there is nothing sealing the hole, so I can see sunlight clearly through the hole.
What should I use to fill this hole in my wall preserving the important stuff going through the hole?
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A better question would be, why is my sheathing getting wet?
The grain of the sheathing suggests to me it is Homosote Homasote. It should not be squishy, rather firm and resilent.
Something is allowing water past your brick barrier, and then, past what was vapor barrier (for the time, 15-30# tar embedded felt paper. I would look up, overflowing gutters can get behind fascia boards and run down the inside of the bricks, soaking the sheathing if the vapor barrier was broken during the bricking (as sometimes happened, also mortar bridging can cause this). In no case is it normal for the sheathing to be wet. Poor tuck pointing (especially around windows) can also allow water intrusion.
Once the water intrusion is corrected, all stud bays in the affected areas should be opened and the sheathing evaluated for viability. Also, opening the cavity will allow faster drying out and possibly see where the intrusion is starting.
As an aside, my 1941 house used a gypsum lath board for plaster.
you don't say what the material is that has a hole in it. Great Stuff works well usually. Let it dry completely (for like a day or two). Hack saw blade (no saw) cuts off excess flush with surface. May want to push in filler to create a dent to allow for cap/finish agent. Spackle/skim over with your favorite skimming agent (something that matches existing surface). I have used vinyl spackling for smooth stuff and sanded, cementicious products for stucco and rock, I'ved used Bondo, Durham's Rock Hard...etc., etc. Great stuff is your insulator and filler then you just need to skim/cap/finish it then paint it.
Best Answer
I would use Duct Seal
I'm surprised whoever installed the AC unit didn't use it, it's used all the time by Electricians and HVAC technicians.
It does not harden; so unlike foam, it can be easily removed and replaced if you have to add/remove wiring/plumbing.