Adding a basement to an existing house?

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Just curious as to the probability of adding a basement to an existing house. It was built in 55 and is a ranch style single story 3 bedroom 1000 sq. It has a 3 ft crawl space all the way around. I have a drywell and well also, no city pumbing at all. Any thoughts on this? Thanks
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Expensive. Two ways to do it. One it to move the house off the foundation, dig the basement, pour the walls, etc, then move the house back. Another is to cut a hole in the floor and start digging by hand and bucket the dirt away.
I just has to be cheaper to move to another house, but maybe you have special circumstances. I can see it costing 100k to do this, but it also spends on the type of soil, ground water table, etc. It may be a better investment, not cheaper, just to build a new house and tear down the old.
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JLagg wrote:

Yes it is totally doable.
When I was a kid in the early 60's a neighbor nearly finished one but he died of a heart attack just before completely the dig.
The guy who bought the house from his widow got a nearly completed excavation, he finsihed the project & had one of the very few basements in the area
SoCal is not noted for full size basements even in the 60s......maybe the random ultilty vault but once slab constr took hold as rare as bsements were they became extinct.
My dad & I toyed with the idea (60's bomb shelter) but never executed
A buddy's uncle dug a bsaement; buckets & a pickup truck....... took him a LONG time
If you're serious you've got think it through.....you can easily undermine your foundation. You've got to support the dirt supporting the foundation or dig far enough away.
I've thought about it for my house but I've got post & pier construction; the project is daunting.
cheers Bob
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BobK207 wrote:

Thanks for the input folks. I live in Michigan around Battle creek. There are a few places around me that have basements even walkout basements. A neighbor actually got under his house and pulled out the dirt with a 5 gal bucket! took a while for that one. Also would it be better to use the cinder blocks or actually using forms or is there really a choice.
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One method is to use insulating concrete forms. You can DIY and you end up with a well insulated basement, a must in your area. Check out www.standardicf.com or www.integraspec.com
You can also put a portion in the ground and a portion above grade and have what is known as a "raised ranch" and have better natural light in the lower level.
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Edwin Pawlowski wrote:

Hello Edwin. Ha! never concidered that idea as in raising the basement to add light. Nice thought there.
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adding livable space increases your homes value dramaticall]y.
saw a show from florida in flood prone areas. homes on slab.
they dug under and placed beams under slab then jacked whole house up, and built foundation after digging it out.
expensive but they got to keep their beach homes, people in pittsburgh flood areas have doe this too.
this old house had a show about the anna mae allcott little women house, they added basement for storage.
hopefully you dont have a brick chimney, that would add hassles and costs
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snipped-for-privacy@aol.com wrote:

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yes it's doable-i worked on a house that was shored in place and basement dug with a skidsteer and an excavator (the skidsteer did most of the digging--the excavator was sort of assisted). then a block basement was built, and we jammed cedar shakes to get a tight fit to the block--didn't move a bit when the shoring was taken out. don't think it would be cost effective to move a house, build a foundation and move it back unless it was some high buck house. i have a friend who jacked his house up about 5 feet, dug with a mini excavator, and built a wood basement under it. ICF's would work, but you need a space to pour, so you would have to jack the house extra high, and let it back down, or you would have to pour it low and add a course or two of block.
where I live retrofitting a basement can easily cost 30-40 grand for a small house. it's seldom worth it.
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marson wrote:

$30-40 thousand for an extra 1000 feet would be tremendous. How else can you get enclosed space for $30/square foot? Finished maybe $50-60/square foot.
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George E. Cawthon wrote:

well i was quoting excavation and foundation only. to get you finished living space is going to cost a lot more than that.
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There is alot to consider I dug out my basement. First get bids to see what the pros think, talk to the permit dept. A few things, what is your water table, just because the neighbor has one does not mean there isnt a spring down below, you dont want a swimming pool. You need to jack, support and monitor house level almost daily to be sure you dont ruin it. You need to figure out how to put in a foundation while removing the old one and keep it jacked up. You need a permit or you can have your home deemed un live able. Its going to be 3x more work than you think.
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Before you expend any money on design work or start digging, check your water table level. When I was shopping for houses here a couple years ago, most of the basements had a musty smell, and the place I ended up buying has a slightly damp basement, requiring me to run a dehumidifier much of the year down there. This area is mainly a thin layer of dirt over old sand dunes. (Look where TopKut meat place used to be, on Beadle Lake Road, for a good example, or the dirt-selling place on Verona, just east of Raymond.) It is also rather swampy, as may be expected with all the rivers and creeks and lakes around here.
I dug out my topo maps, and went to the township office and got a copy of the flood plain map. Near as I can figure, the water table is about 3 feet under my basement slab. (And I'm in a raised ranch, on one of the higher lots in the subdivision.) A house I looked at a couple hundred yards away through the woods, in the next subdivision over, I think the basement floor was right at the water table level. During that open house, realtor had all the doors and windows open, and it still stunk like an old cabin. (Damn shame, because it was otherwise a very cool house.)
I'd call whoever drilled your well, and ask them. Given the address, they could probably tell you pretty closely what the water table is in the area. There may be a reason your place was built over a crawl.
Assuming the water table allows it, the best way to do it depends on the lot and how the house is built. I've seen several houses in BC with dug-out basements, and it is usually hand dug, and smaller than the original foundation, with a mudded-over shelf between the new walls and the original foundation. Doesn't make for a real useful space. If there is good access, a house mover could support the place on needle beams and external cribbing, and jack it a foot or so, and they could carefully excavate from one end by cutting a trench and using a mini-backhoe on a Bobcat, plus a lot of hand work. If there is clear space on the lot to move the house out of the way, that would make the digging much easier. Either option means moving out for awhile- your stuff can stay, but insurance and utilities won't allow people in a jacked-up house. But you definitely want to crunch the numbers to see if it makes financial sense- don't figure on it adding more than 20 or 30 k to the value of the place. And unless you are in a position to pay for it out of pocket, the mortgage folks would want to see real good added-value numbers and real engineering drawings. Almost all the modern basements I have seen around here are poured concrete, but it could be whatever is cheapest and easiest. Reinforced concrete probably stands up to hydrostatic pressure better than block, unless you reinforced the heck out of it. Attached garages and fireplace chimney stacks complicate things, as does figuring out where to add a stairwell in the house. Basements with outside-only entrances aren't a big perceived added value to most buyers.
With the number of houses on the market here locally, and the still-relatively-low interest rate, moving may be cheaper, unless you simply have to keep that house.
aem sends....
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JLagg wrote:

Nobody uses cement block for foundation walls where I live. If you do it yourself and get a little help (like on weekends), you can buy a 3-4 cubic foot mixer and mix concrete and pour a 3-6 foot wall section at a time. That allows you to progress at a slow rate and to maintain support under the house. Easier if you pour the whole thing in one shot, but a big hassle to prepare and pour with an existing house. You will want to get a concrete worker to pour and finish the floor in one shot.
Your house is fairly small, (?50 x 20 or 42 x 24?), means that if you put a support in the middle you can span that 10 or 12 width easily. and have two 10 or 12 foot clear space that run the length of the house.
Post and pier is not a big problem, you just need to figure out the basement space where support pier and beams are needed. Then you can start digging You can dig at least 2-3 feet lower that the support for the piers before you do any supports so that you have more head room. You will move support beams and piers around as you dig out the space, but you can easily use 8x8 pieces to cross 3 of your beams (assuming you have 4 feet between beams) which will give you a 12 foot wide space to dig. What I am saying is that you can futz around a lot if you don't plan ahead, so you need to work out a plan for supporting the house as you dig.
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I thought of that. Well if you are going to do that, build a trough with a big augur to move the dirt out. Power it with an electric or gasoline motor. Maybe you dont need a wood trough, just a ditch in the dirt. Or a conveyer belt. But probably worth doing on good job on it so not too much falls off. For a week, I had the job of shoveling up the sand that fell off the conveyer belt at Ingot Molds at Beth Steel in Bethlehem, Pa.

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Years ago, one of my workmates turned his crawl space into a basement with dynamite...
Nick
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Watch the movie The Great Escape, for excavation and dirt removal ideas.
:)

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space was not only 0" (zero) but the dirt actually came up between the floor joists. Seller of the house gave me a $10,000 price reduction since the house couldn't be inspected for termites.
One day I started digging at the down hill side simply to take a look and maybe excavate a 3 ft. by 3 ft. room to hold a water heater or furnace. I chipped (removed) a 3 ft. gap in the existing foundation and started digging. I got my 3x3 6 foot deep and thought "what the hell" lets keep going. After many evenings and weekends I had dug an 800 square foot area, 9 feet deep. Over the next three years I poured 12" deep by 5 foot wide footings around the full perimeter and started building block wall on the edges of the excavation. 12" block for the first 4 feet and 8" block above. Lots of rebar. Lots of water proofing and drain rock. Drainage all around the perimeter and gravity out to the side yard (took an additional 100 feet of trenching outside in order to get enough fall). Long story short, I ended up with the only basement in my part of California, exquisite recreation room with bowling machine, pinballs and pool table. A decorative set of circular stairs connected it to the great room above. Advantages that I had was that I was able to do my own structural calculations and design allowing it to flow well into the remaining architecture of the house. Would I do it again?? No!! I was younger, could do the sweat equity. If half of our house were not on slab I would have simply raised the house 3-4 feet during construction, dug the basement with heavy equipment (instead of 5 gallon buckets and wheelbarrow) and then lowered the old house back down. Would have been a lot less effort.
Email me directly if you want more details. We can even talk on the phone if you are serious.
Ivan Vegvary
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JLagg wrote:

It is done a lot around here. How easy it is to dig depends on the construction. If you have a post and beam support system, you will need to put large beams across the current beams. A more common older system with a large beam through the center may be easier. My father did this to about two-thirds of his two story house and I helped him mix and pour a good deal of the concrete for the walls.
The cost here is very reasonable. Amazing how much even just one hard working person can do in a day. If I remember correctly, a friend of mine had his dug out in about 2 weeks, ready to pour concrete walls. You just need to find someone who does this type of work.
A major consideration is the soil. Digging is easy if it is fairly soft, impossible if the house is above solid rock or large boulders. A second consideration drainage and the the water table; you don't want a basement floor that is below the water table.
Good Luck!
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George E. Cawthon wrote:

Wow thanks everybody for the great insight on my thoughts of adding a basement. Very much appreciated. It really is an interesting subject and i now believe I have been talked out of it! whew, I have a well that is only 50' down and there is a lot of sand in my area. And now that I think about it my neighbors house does have a bit of an odor as you walk in. Bought the place in 78 and swore i would move in 5 years as that was my very first house. Next place I get will definitely have a basement already there ;)
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