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  #1  
Old 11-08-2008, 10:34 AM
Dilton Doiley,Philosopher King Dilton Doiley,Philosopher King is offline
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How far down under my house can I legally dig?

Assuming that a) I own my house b) I don't hit any water, sewage, or power lines and c) digging under my house won't affect the structural integrity of my house or its foundation, how far down can I dig, from a legal perspective? Can I build a five story house under my own two story home?

I am imagining something like... digging a stairwell out in my basement floor, and then digging out rooms and whatnot, farther and farther down.

Additionally, if I am able to dig down to a certain depth, can I start to dig out, essentially under all the houses in the neighborhood, but so far down they would never know (unless they also dug under their houses) with no legal repercussions?
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  #2  
Old 11-08-2008, 10:39 AM
Snnipe 70E Snnipe 70E is offline
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Quote:
Originally Posted by Dilton Doiley,Philosopher King View Post
Assuming that a) I own my house b) I don't hit any water, sewage, or power lines and c) digging under my house won't affect the structural integrity of my house or its foundation, how far down can I dig, from a legal perspective? Can I build a five story house under my own two story home?

I am imagining something like... digging a stairwell out in my basement floor, and then digging out rooms and whatnot, farther and farther down.

Additionally, if I am able to dig down to a certain depth, can I start to dig out, essentially under all the houses in the neighborhood, but so far down they would never know (unless they also dug under their houses) with no legal repercussions?
You can dig down but not out. The problem comes from needing permits and inspections. As you go down you are going to need to support the walls of the hole so they will not fail. Also as you go down you could effect the stability of your neighbors land.
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Old 11-08-2008, 10:58 AM
The Great Sun Jester The Great Sun Jester is offline
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You'd need to get a building permit and your property taxes would be adjusted according to any improved house value.

You'll probably only be limited by local building codes.
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  #4  
Old 11-08-2008, 11:22 AM
robby robby is offline
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Quote:
Originally Posted by Dilton Doiley,Philosopher King View Post
Assuming that a) I own my house b) I don't hit any water, sewage, or power lines and c) digging under my house won't affect the structural integrity of my house or its foundation, how far down can I dig, from a legal perspective? Can I build a five story house under my own two story home?

I am imagining something like... digging a stairwell out in my basement floor, and then digging out rooms and whatnot, farther and farther down.

Additionally, if I am able to dig down to a certain depth, can I start to dig out, essentially under all the houses in the neighborhood, but so far down they would never know (unless they also dug under their houses) with no legal repercussions?
In most jurisdictions of the U.S., from a legal perspective, you own the land within your property boundaries all the way down to the center of the Earth. The exception are properties where the mineral rights are severed from the remainder of the real estate rights (generally only an issue in western states).

Any water, sewer, or power lines on your property (not owned by you) should have an easement.

You cannot dig under someone's house or anywhere else on their property without an easement.

With respect to this last question, I am actually involved in a project that will involve tunneling under people's houses, businesses, a railroad line, etc. We are installing several deep sewage tunnels that will run between 30 feet below grade to as deep as 150 feet below grade. Some of the tunnels are being bored in soil, and some are being bored in bedrock, and they will be several miles long. Anyway, we have to get easements from every property owner on whose property we tunnel under, regardless of the depth of our tunnel.
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Old 11-08-2008, 01:57 PM
Savannah Savannah is offline
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Well. Be careful. Don't be a Mole Man.
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  #6  
Old 11-08-2008, 06:53 PM
Una Persson Una Persson is offline
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In some (many? All? It could be an OSHA mandate) jurisdictions if you dig a hole and have humans in the hole at any time deeper than about 20 feet, you need a licensed Professional Engineer to sign off on your design for maintaining the structural integrity of the walls. In some places you need a PE's approval to go below 8 feet.
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Old 11-08-2008, 06:55 PM
MC$E MC$E is offline
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Don't forget, with the earth being roughly spherical, the deeper you go, the smaller your owned area is. Think of an inverted, very elongated pyramid.
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  #8  
Old 11-08-2008, 09:59 PM
Boozahol Squid, P.I. Boozahol Squid, P.I. is offline
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Originally Posted by MC$E View Post
Don't forget, with the earth being roughly spherical, the deeper you go, the smaller your owned area is. Think of an inverted, very elongated pyramid.
And once you hit the middle, you're really digging under someone else's house. So definitely not any more than halfway.
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  #9  
Old 11-08-2008, 10:49 PM
Chimera Chimera is offline
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Quote:
Originally Posted by Boozahol Squid, P.I. View Post
And once you hit the middle, you're really digging under someone else's house. So definitely not any more than halfway.
Once you hit the exact center, you're under everyone's house.
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  #10  
Old 11-08-2008, 11:40 PM
ouryL ouryL is offline
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To dig such in Hawaii, you may need a permit so as to protect the water table.
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  #11  
Old 11-10-2008, 11:18 AM
Tom Tildrum Tom Tildrum is offline
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You're not hollowing out some creepy Austrian-style dungeon, are you? Because that would likely run afoul of other laws.

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