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Question DetailsAsked on 4/15/2014

Cost to dig out and construct a 1100sft basement under a existing home on a crawl w 3 beds 3 window wells an bath

Would like to move furnace water heater and water softener down as well. Then also to add about 8ft out off of back off home w New basement under that as well finish off w New Windows and siding

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8 Answers

Voted Best Answer

It has been awhile (2000) since it was done to my 2 story house but it ran me $17,000 to have the house lifted, dug out, concrete poured and set back down.

I did do the electrical and pumbing and added a knee wall so my overall basement was 9' tall. 6' conctete with a 3' knee wall.

The original house (950 sq ft x2 for the second story) had a 6' partial basement under the front 1/3 of the house with the rest had a crawlspace under it.

Be aware that cracking of existing drywall WILL happen.

Answered 3 years ago by loghome


YOU are looking to spend a Pile of money .

Doing simple math , 28x40 =1120 sf .

In order to remove 1120 sf of earthen spoil from underneath an existing structure is going to require an enormous amount of temporary cribbing , using railroad size cross ties for cribbing or 6x8x4 timbers which cost about 20.00 each @4 foot lenght . To stack these 9 foot in height creating a Pier to rest your home on while removing the spoil ,and you'll need about 4 cribs every 8 feet ,rough math = 18 timbers x 4 = 72-timbers for each pier x 4 = 288 timbers, 288 x 6 peir sets= 1728 x 20.= $34,560 in timbers alone .These will be reset every 24 feet or so ,and then moved up successively as you Frame and pour foundation walls ,which will probably cost $60.00sf , pour 24x9 x 8"foundation each pour= 162 cf x $ 60.00 sf = $9720.00 or you could pour footers and set block walls under the home frame exterior, which would require you to pour footers on each side simultaneously and then set cement blocks to create a foundation wall on each side as you continue to excavate and reset your timber cribbing and so on and so on..................................The point being ,you are opening a can of worms attempting to remove the earth from beneath your structure and run the risk of the piers collapsing while attempting such a daunting Task.Of course we are NOT counting Architectual or Permit cost nor real labor costs !

Were we to run out the numbers completely , I would dare say and venture a quess between labor , material and equipment costs you would easily invest $ 150.000 to $185,000 in RAW costs ,much of which would be in material you could only resell to a Home Mover .

Your best investment , would be to relocate to a new home with a full basement

and give up the idea of digging out from under your home .

It is a grand Idea ,and as there are numerous contractors seeking work , I am sure you could find many wanting to accomplish the task,,,,,,,,,,,,BUT , The risks Out weigh the benefits ,unless of course ,You got a pocket full of money burning a hole through your pockets and creating enormous discomfort for You !

All of that being said ,It's YOUR Dream ,and if you desire , Follow IT !

Answered 3 years ago by BentheBuilder


For this type of job, you need plans and specs from an Architectural/Engineering firm before thinking about contractors - and to get a building permit.

Ben's method would work and done incrementally could cost well over $100,000 plus as he says, but this not really the most economic way to approach this big a job. A House Mover or Foundation Underpinning specialty company can usually slide your house onto a whole new foundation, or jack it up on steel beams and hold it there while a basement is dug underneath it, without any intermediate piers. The jacking/move cost would probably be on the order of $30-40,000, and a new basement probably about $40-50,000 - rough ballpark, though I have been involved in some 1000-1500SF single story jobs that went for under $70,000 total.

I have been involved in a fair number of these type jobs - and the way the numbers come out, if there is room on the property to move the house, it is almost always nearly as cheap or cheaper to build an equivalent square footage (basement plus ground level) addition rather than add a basement under the house, and that way your new footage is half above ground so worth more on resale, plus you do not lose use of the house for a month or two. Second cheapest is usually sliding house to a new foundation, if property is large enough to do this - though house is totally cut off from utilities for a week to three. Most expensive, and usually only done in tight city environments or with full 2 story or higher houses, is adding the foundation in place, though your utility interruptions should be on the order of hours at a time rather than days or weeks.

Talk to an architect - I think you will quickly lean towards the addition option rather than adding a basement - it is just too expensive to deepen foundations in most cases, plus you WILL get cracking in the house and possible water and sewer pipe problems in a move/underpinning job, which is not the case with an addition. This become more likely the case since you want to add 8 feet off the back of the home anyway - so why not just enlarge the addition and do it all that way - MUCH simpler, and MUCH less disruption of your life, and you get much higher resale return on your investment.

Answered 3 years ago by LCD



Answered 1 year ago by BENNYRED


I am having a 28 x 40 cabin picked up and moved for $6,000. The basement estimate is $24,000 for a total of $30,000. Then I will have the expense of putting in stairs inside the cabin to access the basement and replacing the deck. Other costs will be unhooking power and water, removing two trees for the move and dirtwork. I figure total cost is going to be close to $40,000. But my cabin will go from 1,120 square feet to 2,240 square feet.

One end of the basement will be a walkout, so they will just stud up that side and not pour concrete walls.

Also decided to add radiant floor tubing in the basement floor when the concrete is poured for future heating. I was told $1.00 per square foot additional for this.

Local Amish people do the actual cabin jacking up and moving off site then back onto the foundation.

Location South East Iowa/ Northeast Missouri.

Answered 11 months ago by SoutheastIowa


ide be interested in talking to bennyred. we had quotes about 5 years ago in that exact ballpark for a new 1000 sq living space dug out and poured from crawl. didnt have the funds available back then but interested now. is there a way of contacting him? thanks tim

Answered 6 months ago by pipeandwire


I would also be interested in contractors who can take this on in Southern California. If anyone has got the contact information for bennyred or has a contractor it would be great if you could pass along. Thanks or

Answered 4 days ago by Guest_9718690


To people reading these answers and rough $ amounts - note the original question included in his desired scope of work, adding 8 feet to the back of the house with basement. For 1100SF house, lets assume maybe around 40LF back wall assuming single-story house - so 8x40=320SF NEW basement and addition, which would normally be from about $30,000-100,000 depending on construction type and local building costs.

Plus new windows and siding - another $20,000-40,000 or more in most areas.

Certainly those additional scope items would NOT be included in the $ mentioned in answers, which had to be for just putting a basement under the existing house.

Also might be worth noting that the scope of work for the original question might well, by the time all was said and done, cost more than a new house with the square footage and full basement - one always has to pay attention to the remodel/addition cost going into a house relative to its market value - i.e. it is easy to put more into the house than it will be worth at resale time, especially if the resulting house will be oversized or over-classed for its neighborhood.

And of course considering the value of the home itself if it is an older house - doing major remodeling an older house, unless pretty much a gut and rebuild from frame (if in good condition), can many times end up with a negative return on the "investment" come resale time, so one needs to consider whether this is their "forever" home or not and how many years they are realistically likely to live in it. Advice from an appraiser or your favorite realtor can be valuable in that case - though of course the realtor will have an inherent bias toward moving to a new home which already has everything you want.

Answered 2 days ago by LCD


Search basement dig out and you will see my educational videos on this subject, user name njstoll on youtube. My dig out videos are rated #1. I promise you will learn something.

There are so many variables when considering a basement dig out. Access, soil type, water table, parking if you are in a city setting, engineering, permits, where to discard soil / rock. condition of existing foundation walls, condition of existing beams, structural condition of home, property value.

Your first step is to consider if your property value will support the cost to lower a basement and liberate the space. If you live in an area that has depressed home values, I do not recommend a dig out, unless you are dead set on remaining in your current area for a long time. If the current value of your living space (excluding the basement) is less than $165 per square foot, it may be best to look for another home that suits your needs. Basement dig outs are a huge commitment.

If your property value will support an basement dig out project, design is especially important. Basement dig outs can be designed many different ways. Over engineering can put your project over budget. The design should be suited to the structure. For example, If you have a 2 story framed home and you engineer the new foundation underpin for a 3 strory masonry home, you will elevate the cost of your project. The engineering design should be structurally sound for your specific project. I have videos that will give you an idea on engineering an beasement dig out.

Consider what is beneath your home. If you live in an area that is known to have rock outcrop, the costs of your basement dig out will increase. Drive around the neighborhood. Do you see any huge rocks, boulders or bluffs next to the road? If so, your costs will increase. I am currently on a project that has an immense amount of basalt that needs to be removed. Basalt / granite removal requires 10 times more energy to remove than sticking a shovel in the ground. You should know what needs excavated BEFORE you start a basement dig out.

Consider water management. The last thing you need is water problems in your new basement. If you are in a low lying area, water will be an issue. Even homes on a hill will require water management. If someone tells you that water will not be a problem, you are getting poor advise.

Every dig out MUST have water management. Ground water is something every basement dig out will be subject to. If your new basement will be below grade of the surrounding homes near your home, you will be the water magnet. Water management is not expensive once the basement is dug out. It makes no sense to exclude water management. It is also important to design proper discharge. The best way is to remove the water from the property by discharging to a storm sewer. If you do not have a storm sewer on the property, then drywells should be included in your design. Be sure to keep drywells on the low side of the lot and a minimum of 20 feet from the foundation. Tie in all downspout leaders. You do not want to dump roof water into the backfills. Watch my videos on this subject (Youtube: njstoll user name)

Consider your basement floor plan and lighting. I always recommend egress wells when doing a basement dig out. Egress wells will qualify the liberated space for bedrooms. Even if you do not want a bedroom in the basement, egress wells are well worth the investment.

Basements are very dark if you do not have natural light entering through windows. Natural lighting gives the appearance that you are not living in a dungeon. The more natural light, the better. Egress wells also provide an escape route in the event of fire or other emergency.

Consider benching your mechanical area. Most basements have a furnace, boiler, water heater, etc. If your mechanicals are in the basement, you can bench that area. There is no need to spend the money removing and re-enginnerering all your mechanicals, unless you are replacing or redesigning.

Consider heated floors. Your new basement floor will remain ambient (about 55 degrees). Before pouring a new slab floor consider the flooring. If you are using porcelain tile, it will be cold. If you plan on carpet, be sure to use a high quality anti-microbial pad below.

Basement dig out vs. a new addition. If you live in an area where property taxes are high, or your lot will violate zoning code by adding an addition, a basement dig out will make sense. Say you have a 2 story 2000 sf home and you need 1000 sf of extra living space. An addition will cost more than a basement dig out. The addition will also increase your property taxes much more than a dig out, as the addition expands footprint of the home and the city will tax the new addition accordingly.

Hope this helps you out. If you have any questions, feel free to call me.

If you go to my youtube page, be sure to subscribe and like.


Answered 1 hour ago by njstoll

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