I need some help with a request I received recently to convert a crawl space foundation under approximately 75% (48 feet) of an existing home, to a full basement with 8†poured concrete walls. The house is a ranch with a steel I-beam in approximately the center of the house running from side to side. It was built in 1972 and was moved to its current site in 1987 where it was placed on an 8†block wall. Soils in our area (north of Atlanta, GA) are predominately hard red clay. The house is situated in the center of a 2-acre lot of converted pasture; access to all sides of the structure is very good. The crawl space wall is approximately 24†high at its lowest point and 42†high at its highest point. The lot slopes down from back to front. The grade has been shot and it appears the finished basement wall height will be approximately 9 feet. I will be involving a civil engineer who has helped me with various projects during the past 10-years. Any advice regarding shoring, excavation methods, etc., would be greatly appreciated.
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While I haven't done anything like that myself. There was a really interesting article on this on JLC very recently called "Retrofitting Basements". It detailed how a San Francisco contractor does what you wnat to do all the time
http://www.jlconline.com/cgi-bin/jlconline.storefront/3db6e7dc006ce273271a401e1d290697/Product/View/0208retr
Kevin:
Thanks for the post. I read the article, then printed it. I found the information very useful.
Scooter
My first thought is that, from experience, this is expensive as well as dangerous. You have a wide open lot and know that the house has been moved before so that's no big deal. If would be less expensive and faster to dig and pour a new foundation on the lot and move the house over to it than to try to work in under the existing. The occupants might only need to be out of the house for a few days. If they are in love with the current location exactly, then move the house off, dig and pour, then move it back. In my mind, the reasons for saving position and working in under are; large cmbersome house, small close lot, access problems for movers.
If they showed interest in moving it to a new foundation on the lot, I would aim to price it to where you could buy them a week at Disney World while the shift happens and time it all closely.
But that's in an ideal world....
Excellence is its own reward!
how come you always think out side the box - neat idea.
I would agree that your idea makes a great deal of sense. However, since moving the house to the lot in 1987, the owner has added an elaborate, multi-level deck on the back, and a screen porch addition on the side not affected by excavation. My first reaction to his request is consistent with your remarks - dangerous and expensive. Thanks for your post.
Given that - (thanks for the compliment, BTW coolcall. That's why I can make a few bucks as a consultant occasionally) you can't move the place;
The porch will be a pain, because between that and the portion still without full basement, you will not be able to deviate from current elevation without racking roof joints etc at tie-in.
I might have some old photos on floppies I could look for later if no-one else helps much. I'm too dog-tired from heavy demo all day to look now. Feel free to remind me via email later if I forget. I have done this wiuth a house still in operation and functional but it can be a real pain in the pocketbook.
My thinking is that you should get at least a consult from a house mover.
He may be able to place the beams to hold it for you while you or your subs do the work in under the house. Then you don't have a major investment in cribbing and beams to somehow re-coup. If he's an experienced mover, he can tell you more than I can from being able to see the place. I am not a mover and he wouldn't be moving it but all the skills needed are in his head just waiting to be tapped.
It can also be dangerous to give or take advice on this sort of thing online because we can't see all the things that impact methods and safety concerns. We can only go based on what you describe and you might not fully know what to describe so mis-communications can lead to dangerous situations.
Best advice I can give is this.
Be sure to take regular coffee breaks to sit, study, and analyse with Mr Murphy sitting on your shoulder. Think it through before you do and it'll come out all right..
Excellence is its own reward!
Scooter,
Take Piff's advice about the professional mover doing the shoring up, the last thing you need is to have the house shift or worse come down on your head while you are working on it. After you get it shored up I would rent both a bobcat and the smallest excavator you can get so that you can get underneath and dig out the red clay and move it out with the bobcat. A few points about properly waterproofing the basement. I live in northeastern Ohio and most of our soils are clay. First make sure you place perforated drain tile on both sides of the footer and connect it to a sump crock assuming you don't have enough natural fall for drainage. If you do you can just run the pipe to a point lower than the footings where it can discharge. Second make sure you place at least 4 inches of washed gravel or limetone etc. under the concrete floor and around the basement walls up to about a foot below finished grade. We use #57 stone which ranges from about 3/4" to 1 1/2" in diameter. Make sure your mason parges the outside of the walls with about a 1/4" minimum of mortar up to grade and follow that with an asphalt base foundation coating brushed or better yet sprayed on. We have a local guy with a van based sprayer setup that does this for us but you may have to do it by hand since there are not a lot of basements in your area. The stone backfill will enable the water to reach the draintile quickly instead of running along the wall and possibly working it's way in. Clay, be it yellow, red, or whatever has very poor drainage characteristics and the proper backfill is critical to creating a dry basement. There are some types of drainage boards that are supposed to work by placing them against the block wall and not needing gravel. I prefer to use what I know from experience works. Also before you pour the concrete floor put down a plastic vapor barrier,(code requires this in our area). Finally I would recommend using at least ten inch block, preforably 12" for 9' high walls. Good luck.
Mark
Thanks for the info. Believe it or not, we do a fair amount of basement homes in the north Atlanta area. I've built about 80 houses with basements. You are spot on with the best ways to make for waterproof walls and slabs that remain dry. I appreciate your post.
Scooter,
Thank's for the compliment. I visited the Atlanta area about 4 years ago and didn't see many basements but we were south of town about 30 miles. I was unaware that there were many basements being built. Seemed to me that you could get an awful lot of house for the money in your area. Wondered how you guys make any money.
Mark
After 10-years of building new homes, I oftentimes wondered the same thing!
Therre's been a lot of discussion on the forum here about how many builders in the Atlanta area are doing shortcut, substandard work. That probably has something to do with it..
Excellence is its own reward!
Piff and Scooter,
I did see alot of substandard work/ materials but in all honesty you see the same thing in our area with some of the chain builders, most of whom are selling space. Some up around the greater Cleveland area are selling what they represent as custom homes with more choices than others but in my opinion they are still selling what amounts to a tract home. In some of the counties not to far from where I live you cannot even find a "yankee" framing crew as they have all turned to doing something else. This is because the Amish have taken over that market by pricing their work so low. More often than not the quality is also low. I have trimmed some houses framed by Amish and have found most of them to be a nightmare. This is not to say that all Amish are butchers as the best framer I know happens to be Amish and is both expensive and in high demand. He is the exception not the rule. All this being said however, I would have to say that you can get a lot of house for the money in our area as well but not like I saw in Atlanta. As is probably the case just about anywhere there are a lot of really good builders in our area but there are also a lot of butchers. Be well.
Mark
I'm Mennonite and most of the brethren I know are good craftsmen so when my stepson went to Alaska a couple years ago and found his frist job there with a Mennonite fellow, I was pleased.
Then he told me abotu one of the first days on the job. They had a door that needed tweaking. He was on the way to the truck to get his screwdriver and sharp chisle when he heard a loud WHAM! He turned around to see this guy 'adjusting' the door with a full sized sledgehammer.
It takes all kinds!.
Excellence is its own reward!
Hey Prof- was wondering where in northeast Ohio you're located? Let the thunder crack and the waves roar.
We're going on.
Rez,
I live just north of Warren which is about 25 miles from Youngstown and about 55 miles from downtown Cleveland.
Mark
I'm in Ohio on lake Erie. I use to drive into warren down rt46 I believe. Not to far from the Ashtabula -Trumbull county lines on the west side of the road there is this old beatup victorian sitting there. Someone mows the lawn and that's about it. Everything about it is just as it was back when. A friend and I stopped there once and she took some photos of it. Paint is totally gone on it, hole in roof where a chimney use to be, some of the decorative shingles are still on the turret, the gingerbread spindles on the south side are so sun and weather beaten that the part of the spindle facing southwesterly has evenly wore away on all the spindles. Never seen such a thing. The diameter of the poisonivy vines crawling up the sides of the house are big as a silverdollar. I'd give about anything to get to walk thru the place and snap some pics. Worth the look- see if your in that area.
Let the thunder crack and the waves roar.
We're going on.
Edited 10/25/2002 2:14:23 AM ET by rez
Edited 6/1/2007 12:33 am ET by rez
Mark,
I tried to send you an e-mail in response to some of your observations. Please send me an e-mail at: [email protected] and I'll get back to you. Thanks!
Thanks again for your insight. I think the house mover suggestion is excellent. The support structure (beams or cribbing) is the part giving me the most heartburn. Once more of the cost figures are in place I'll know if, and when, this project will move forward. If its a go, I'll probably send you an e-mail as more details of the project materialize.
The only downside to this from the point of view of the house mover is that it ties up his steel and cribbing for kind of a long time. So, you may find that his rental rates for it will be rather high. Pencil out a comparison with having your house mover put it up on stuff that you own. If you have room to store it, this could become a specialty of yours.
-- J.S.
Maybe. The mover we see here has enough beams and cribbing to keep five or six setups in operation at once though. He'll get paid for setting the beams, not rental really. When moving or jacking up a house, the major part of the labor investment is in settup, not moving day..
Excellence is its own reward!
Back to original query:
My daddy did this when I was kid in IL with hard red clay, he did 4 ft of the wall at a time, never had any problems, never used any shoreing.
Did it myself a few years ago on kid's house (hand dug with WheelBarrow yet) and did one 38 ft section all at one time, but that was in hardpan. Left 1 ft of earth inside existing crawl space footing and then poured 12" thick retaining wall 2 ft inside house outside line - left a nice almost 2 ft wide countertop.
Scooter:
I was recently involved in a lifting project myself. We subcontracted with a houseraiser and it was the least expensive part of the entire project -- about $7500 in the Seattle area for a two story house. It was money well spent: with an experienced lifter, I didn't worry about the house coming down, and *his* pocketbook was on the line if anything bad did happen.
I would look into getting some sort of insurance if you decide to do anything like that yourself -- and make sure the lifter is insured as well.
Thanks for the ideas. If you don't mind me picking your brain, I have some specific questions concerning your project. For instance: Did you raise the house or did you stabilize the structure at its existing level? Also, how big was the area you excavated, including depth of cut? What equipment was used for the excavation and how long did it take. Once you were done with the excavation, what type of foundation wall was constructed - block or poured concrete? Any feedback would be very helpful.
Thanks
Scooter:
The house here was raised about 2-1/2 feet to make more headroom in the old basement (went from 6-1/2 to 9 feet).
Originally, only part of the house's footprint was excavated to basement depth, the rest was crawl space. In the remodel, the whole footprint was excavated to full depth, which was about five feet below grade. A bobcat and a small track hoe were used for the excavation. Since a garage door was put in at the front (this property has a sloping grade down to street level at the front), all the dirt just went right out the garage door opening. I'd guess about 95 yards of dirt were hauled off site. Excavation itself only lasted several days.
We used poured concrete walls up to about 6 feet, and then 3-foot pony walls to bring the ceiling height up to 9'-0". Using concrete all the way up would have had some structural advantages, but the wood pony walls made it much easier to apply siding and make the house look less "industrial".
We consulted with an engineer, who pointed out that the use of pony walls also made it necessary to design the concrete walls with enough steel and footing width to withstand the pressure of the backfilled dirt. This wasn't immediately obvious to me, but when you think about it, the walls have to basically be designed as retaining walls, since the floor joists won't keep them from tipping in due to the separating distance of the pony walls. Think of a large piano hinge connecting the pony walls to the concrete. Not much bending strength can be transferred through this connection.
On the other hand, if the concrete walls go all the way up to the floor joists, then the joists act to keep the walls upright.
Hope this information is helpful to you!
Thanks for the details of your project. I too am considering pouring concrete walls approximately 7 feet high and then framing the remaining wall to acheive 9 feet. Your comments concerning retaining wall strength are well taken and timely.
Thanks again.