drywall - What did I drill into? - Home Improvement
2021-6-5 · If the magnetic stud finder is showing response across a good part of the stud cavity then there is probably a metal duct in the wall. This could be a stove hood vent, a dryer vent or a heating duct. If the magnetic finder is showing just a narrow range near where you drilled the hole then the item in the wall might be a metal pipe such as a sewer vent stack, an iron water pipe or an iron gas pipe.
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