Adding on and digging a Basement/Cellar under preexisting structures.

Ive often wondered about this too. I have an old 1700's farm house with a very small basement area but several wings with "Crawl spaces" beneath. Id often wondered about creating a basement beneath the exicdting wings but have never found a contractor or engineer who was conversant in techniques.

So we built a new two story workshed and studio outside next to the barns.

My grandfather did just that in the 1960s but before digging out a basement he place a concrete wall around the area to be dug out so not to weaken the soil supporting the weight of the house.

If you do not do this the soil under the foundation wall could collapse inward into the dug out area.

didnt he undermine the original wall when he dug beneath to set the new foundation? Or did he just say "hell with the room size Ill dig an interior wall and foundation"

Lord this was over 40 years ago so I do not remember details.

Let see he did not set a new foundation he placed a wall parallel and inside the existing foundation in the ground so that over time the soil under the existing foundation would not move into the hole that was then dug out for a basement and result in a collapse of the foundation.

That at least how I remember the project 40 years in the past.

As a greedy contractor, I probably shouldn't tell you this but....the easiest/fastest/cheapest way to do this is to simply build a basement in front or behind, or to a side of your house and move the house over it when you are ready....but doing this would require some major assistance.

If that is not possible, it still can be done....several different ways. The "Big Dig" in Boston is something you might look at for ideas.

My friends did this years ago, they just left the footings, so they had a bit of bump out around the outside wall. Talk to you building department.

my house is like a rabbit warren. It has all kinds of separate "Wings". That was the way **** was done in the [ast as the family grew bigger and /or more prosperous. The original house is Federalist and everything else sorta "Telescopes out". Id have to move the wings away and then dig a basement and then move the wings back. Sounds a bitch to glue the wings back together. Besides, we went and put this entire "tin" roof all over with rolled seams and I dont wanna spend anything more on that fuckin huge roof.

Why don't you check with your neighbors... If people in that part of the country do not have basements it is because they would be full of snakes, or closer to the Mississipee would flood or float out of the ground because the water table is so high...

You are right, lands near rivers have high water table.

prolly no danger of hitting water, but depending on where in Kansas he is, he's likely to hit sand.

I would definitely consult someone with some building experience in the area before I tunneled under my house.

I'd really like to see some pics of your house/barn etc. In your case, moving the house isn't an option anyway....from what I remember, the age, the plaster walls, and said wings, would make it near impossible.

A modern standard home....a 4 square....is the easiest to move, ranch style, not so easy, or houses built on slabs....it all can be done, but with like all things it will cost more. For the DIY'er, tunneling and filling as you go would prob be the best option, but as Fido and RH said, ask around in your area first.

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I live about 5 miles from the big Miss, and it makes a huge loop around the county I live in, so on three sides we have the river...plus the Ohio dumps into the Miss about 15 miles away....and we set right on top of an ancient aulacogen..."the New Madrid fault"....so basements here are not very common, and many of those that exsist do have minor to major leak problems. Often, during the spring/early summer...the ground here becomes squishy, one flip of a shovel, and you've hit water. Our well, for watering the grass and such, is only 18ft deep....our two wells for city water are 115 and 120 ft....and very clean because of the mile deep sand deposits that fill the rift.

It accounts for Mark Twains remark about the distintive archetecture of New Orleons Cemetaries, because there is no point burying below ground if people will simple float to the surface... I had a buddy from Texas who said he never spent a whole night in his own bed for a year after returning from Vietnam, but would always wake up under the house... He would hear a noise and out the window he would go... I asked: didn't you have a basement??? No basements there, and if some one had a basment it would always be full of snakes

Ah yes triple points with running sands can spoil yer day. I have to load some pics of my house. I send my pics by email but Ive never done the Upload thing to PHotobucket. Our home sits on very competent bedrock and we live on a hilltop, so basements are very much with the plan.

I only did the consideration as a means of discussion. We actually did a very nice job of creating this 5000 sq ft out building with a doremr roof second floor as a studio office and a big garage workshop in the firts floor.

There is a town about 9 miles south of me that has a N O style cemetery, at least in the older part, modern burial techniques have elemenated the need for that.

When I was a kid 35 yrs or so ago, I remember coffins popping out of the ground in that town being the talk of the county, but I've never found any evidence of that actually happening.

A modern built basement, with formed concrete walls, with some proper care will generally keep water out....and snakes and other critters....even here in the old swamplands....but the older style, dirt cellar, or even half ass built concrete ones are a haven for anything that crawls, burrows, slithers...etc.

If your water table is that near to the surface is having a water proof basement a good idea?

I have a mental picture of the basement floating upward taking the house with it.

I've never known a basement to lift a house, {won't say it can't happen though, anything is possible} but the mass alone should keep it in place....50 tons for a small house. With our sand base, the water just can't build up enough pressure to lift that much weight.

But, an inground pool if emptied, can and will float up, just like a boat, seen that with my own eyes....most people will leave them half way full or so year round.

The town I mentioned last night, just put in a new city pool about 5 yrs ago, they made huge anchors all around it with rebar and concrete, I don't remember the yardage, but it was a butt load of extra poured in there.

I'd love to see pics too!

So.. you want to remove what is supporting the house and replace it with something else while not supporting the house while you do this?



You may find house jacks are a lot cheaper than repairing or replacing your house. (That assumes you are skilled enough to place them properly so they don't collapse as you dig around them.)



Make sure your life insurance is paid and get a rider on your home insurance so they will cover any damage from you doing this.

I used to be involved in some construction from the design standpoint, but I'm no expert in this question. I'd listen to 2packs and whoever mentioned watertable first.

I've two experiences - one related to a vacant lot down the street that someone bought and put in a slab*, and then moved a 2+ story victorian onto it. The victorian had traveled across nearly all of Los Angeles, from Boyle Heights to Venice, no easy matter, to arrive at our corner.

*I'm doubt it was a slab, I'm thinking what? - it might well have been some kind of foundation, probably was. Will have to find that photo... The house was restored by the fellow with what I think of as rescued maple floors, and much else. Sigh, the photo is probably only in slide form (I have the neg somewhere, as then I was using Red Tag photo, that gave both slides and negs). It was a catch in that the guys looked like they were holding up the house. Ok, maybe only a catch for those on our street.

My second experience was with my own house, an old bungalow which rested on a by then flaky cripple wall.. in an area not in a liquefaction zone, but not all that far away. I ended up holding up two ends of the house, the wider ones, with a new foundation, designed by me but signed off by a structural engineer (our landarch firm used to design strong). Sometime later, on selling the house, a new structural inspector insisted on under house piers. I saw his point. It was a loss of money re selling price but I agree good for the house, which I still care about.

When I first read this question, I could see jacking the original poster's house up and putting in a serious foundation as the obvious answer, but then I saw 2packs point, re a not-far move, if possible.

Hmmm, piers might be in order as well.