Cutting a hole in foundation wall
March 25, 2014 6:57 AM   Subscribe

Cutting a hole in foundation wall?

We have an 1850-built house with a stone foundation and a more recent one story addition with crawlspace. We're thinking about (somehow) cutting a hole through the thick stone wall so we can bring ductwork into the crawlspace to eliminate the need for a second heat source for the addition. Our concerns are safety (foundation is holding up the house) and cost / hassle. Is this a major project or something that someone could reasonably do?
posted by dabug to Home & Garden (8 answers total) 1 user marked this as a favorite
Best answer: Without having particular engineering expertise, I'd say it's probably very doable. Another option might be to go through the wood framing that presumably sits on top of the foundation.
posted by jon1270 at 7:03 AM on March 25, 2014

Best answer: I think you definitely want to get the opinion of a qualified contractor.
posted by Thorzdad at 7:16 AM on March 25, 2014 [4 favorites]

Best answer: I think you definitely want to get the opinion of a qualified contractor.

Agreed; I wouldn't suggest DIY'ing this.
posted by jon1270 at 7:19 AM on March 25, 2014

Best answer: How big is the duct? I have drilled large holes through foundations to run 6" duct pipe with a rented hammer drill and hole bit designed for that purpose from Home Depot. If you are just running duct pipe, this is pretty easy and doable. It didn't take that long to drill the hole. If you are cutting large square holes to run main heat and return ductwork, the job is likely more complicated.
posted by fimbulvetr at 7:20 AM on March 25, 2014

Best answer: This is what I rented. Rotary hammer drill, up to 6" holes through concrete and stone.
posted by fimbulvetr at 7:35 AM on March 25, 2014

Best answer: This is done all the time to put in new basement windows, HOWEVER you've got an old house and there's no telling how things have shifted over the past 160+ years. Get a good contractors and/or structural engineer to have a look and recommend solutions.
posted by blue_beetle at 7:44 AM on March 25, 2014 [1 favorite]

Best answer: You want to assess, or get an assessment of, the sill beam or plate that sits on top of the foundation wall, and how well it will support the loads above it once you cut a hole underneath it.

Something you may want to look into is using a small-duct high-velocity distribution system for that addition, rather than a big old standard duct. This would permit you to use a much smaller wall penetration not likely to cause structural problems. Ditto the floor penetrations in the additions. And these ducts are tighter and can be better insulated so there's less distribution heat loss. These systems are particularly useful in retrofitting historic buildings, and are quick and easy to install. They should be able to connect to your existing furnace, perhaps with a booster fan in the mix.
posted by beagle at 8:21 AM on March 25, 2014

Response by poster: Thanks everyone, lots of good suggestions
posted by dabug at 8:45 AM on March 25, 2014

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