Math Check On Amount Of Concrete For Poured Foundation? - Building & Construction - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum Math check on amount of concrete for poured foundation?
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05-02-2007, 01:03 PM   #1
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## Math check on amount of concrete for poured foundation?

I'm just playing with some numbers in order to estimate what it would cost to build the following:

Poured concrete foundation
51' 4" x 31' 4" (simple rectangle)
8" thick walls throughout
9' wall height throughout
24" wide x 12" thick footings throughout
4" thick floor

I did not account for any window or door openings figuring that the amount of concrete those would displace plus displacement by rebar/reinforcing wire would about make up for the fact that I did not account for the footings for the support columns. I ended up with 65 cubic yards-seems like a lot to me, but I've never poured a foundation either. Does that sound right given the dimensions?

05-02-2007, 01:30 PM   #2

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67 yards, with finished wall height 8'8"

 05-02-2007, 01:43 PM #3 Member   Join Date: Oct 2006 Posts: 167 Rewards Points: 180 Thanks a lot! From what I can tell around here concrete runs about \$65 a yard delivered, so allowing for surcharges for the partial loads I'd probably need on the footings, floor, and walls, would \$6000 be a good estimate?

 05-02-2007, 06:56 PM #4 Extreme DIY'r Adk's, NY   Join Date: Nov 2005 Posts: 324 Rewards Points: 272 if you're in the estimating phase for pure concrete material that sounds safe... you will have three pours. I assume you will eventually quote this out you're just doing preliminary budgeting quotes? Dont forget excavating, forms, rebar, remesh, argon/vapor barrier, and/or slab and/or wall insulation, wall and footing sealing, drainage, sand for backfill, etc. I'd say this job hired out would be \$12-15k easy depending where you are.
05-02-2007, 10:12 PM   #5
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Quote:
 Originally Posted by crecore if you're in the estimating phase for pure concrete material that sounds safe... you will have three pours. I assume you will eventually quote this out you're just doing preliminary budgeting quotes? Dont forget excavating, forms, rebar, remesh, argon/vapor barrier, and/or slab and/or wall insulation, wall and footing sealing, drainage, sand for backfill, etc. I'd say this job hired out would be \$12-15k easy depending where you are.
Thanks again for the info. Basically I'm trying to get an idea of how much it will cost to do a good poured foundation. Eventually I want to construct a house and be my own GC, but I'm not sure whether I want to go stick built, do a modular, etc...either way I want a nice, dry, full height basement. \$12-15K is less than I thought it would be to hire the entire job out-so could I assume \$20K would be the extreme high end?

What is your opinion on insulated concrete forms? I saw them demonstrated on one of the home shows, and I've done some research on the internet. They look easy enough to set up. I've worked construction during summers off from school and I'm relatively good with my hands. I've helped out on some foundations from footings all the way up, etc... I was thinking that with some more research I could tackle the job with a friend of mine who's been in the construction business on his own for about 5 years as the "supervisor," and 4 or 5 more friends as a crew.

Assuming that ICFs were used and the labor for the pour (not counting the concrete truck's time) costs me a 30 pack and a BBQ, could I knock that price down to \$10-12K? One more thing-are the footings overkill? I picked those dimensions based on what I remembered from a job, but I may have overestimated. I believe in overbuilding things to a point, but if it's an expensive waste of concrete, I'll downsize.

Last edited by Badfish740; 05-02-2007 at 10:21 PM.

 05-03-2007, 08:23 AM #6 Member     Join Date: Oct 2006 Location: Minneapolis/St. Paul, Minnesota - Latitude 45.057 Longitude -93.074 Posts: 4,068 Rewards Points: 2,626 From and energy standpoint, ICFs are rarely economically justified considering the temperature difference between the soil and the interior basement. They are great above grade!!!. Above grade is where you need the insulation. If you go with ICFs you better make sure you have "friends" that are experienced and qualified with pumping concrete (another cost) AND bracing lightweight non-rigid forms. - It is not for amateurs. If you pay with a 30 pack, you should look closely at the qualifications. Remember - any goof in the ouring (honey combing, cold joints, bridging, lack of vibration, over vibrating, etc.) will be hidden by the ICFs and you will never know untill too late. - One of the reasons for using exposed systems like block and conventional poured. I never did see anything in your list for drain tile and sump pumps. If I thought ICFs were good, I would use them in place of wood above grade and get a real home!
05-03-2007, 09:02 AM   #7
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Quote:
 Originally Posted by concretemasonry From and energy standpoint, ICFs are rarely economically justified considering the temperature difference between the soil and the interior basement. They are great above grade!!!. Above grade is where you need the insulation.
Insulating the foundation isn't why I'd want to go with ICFs. My reasoning is that they don't require the use of either metal forms which I'd have to source from somewhere, or a whole lot of lumber. It is appealing to me to order the ICFs, put them together, pour the concrete, and leave them in place.

Quote:
 Originally Posted by concretemasonry If you go with ICFs you better make sure you have "friends" that are experienced and qualified with pumping concrete (another cost) AND bracing lightweight non-rigid forms. - It is not for amateurs. If you pay with a 30 pack, you should look closely at the qualifications.
I thought this was a "DIY" forum? I don't construction for a living, as a matter of fact I sit behind a desk all day. However, that doesn't mean that I'm incompetent, and it doesn't mean that my "friends" are unqualified. On the contrary. I grew up in a small town and I ended up going to college, but I have a pretty close group of friends who took a different path and work in various fields of construction. By that I mean in business for themselves and quite successful-not drunks who float from job to job. The four or five guys in question have a lot of experience with poured concrete foundations. I'm sure if all of us talked with others in the business and really did our homework, between that and our collective experience we would do just fine. Maybe the 30 pack analogy wasn't the best idea, but the bottom line is they would be more than happy to lend me their time and experience for a couple of days in exchange for little more than a few cold beers and perhaps an afternoon of fishing. I'm not picking up unemployed alcoholics off the street.

Quote:
 Originally Posted by concretemasonry Remember - any goof in the ouring (honey combing, cold joints, bridging, lack of vibration, over vibrating, etc.) will be hidden by the ICFs and you will never know untill too late. - One of the reasons for using exposed systems like block and conventional poured.
Good advice that I will certainly heed. Thank you.

Quote:
 Originally Posted by concretemasonry I never did see anything in your list for drain tile and sump pumps.
I'm still researching what the best drainage system would be, but my basic idea is to do a perimeter drain with 4" PVC slotted every six inches buried in a shallow trench beside the footing so that the top of the pipe is roughly even with the bottom of the footing. The pipe will lay, slots down, in a bed of washed concrete sand. At that point the trench will be filled with concrete sand, covered with landscape fabric and backfilled with 3/4 stone. Not sure how much stone to put down before it's backfilled with dirt. What would you recommend? How about sump pit sizing? Can a sump pit be too big? As for the pump itself I have a source that can get me just about anything I want at cost, so I'll be sure to overengineer that as well

Last edited by Badfish740; 05-03-2007 at 09:05 AM.

05-03-2007, 09:25 AM   #8
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## Math check on amount of concrete for poured foundation?

You can have all the friends you want help on an ICF foundation, but you should hire at least one person that has the know-how. It is not just like "dumping" wood or metal forms full of too wet concrete. If your forms move, you are dead in the water with a mistkae that will tkae thousdands of \$\$\$s. - When the forms start moving, there is little you can do. The bracing if far more than most people are accustomed to.

If you want a dry basement, do not scimp where it is important.

Do not use the "dirt" as a backfill unless you are in a gravel pit. Above the drain pipe, use well graded clean sand and 3/4" maximum size rock. If you have all 3/4" rock it is easy for silt nad clay to wash in and plug the rock or the filter fabic. Make sure the backfill adjacent to the wall is clean and permeable, so it can allow the water to drain and minimize the pressure behind the wall. If you do not have standing water behind the wall, it is hard to get water into the basement, especially if you have sand under the floor slab.

If you plan on finishing the basement, put a layer of 6 mil poly under the slab to allow more choices of floor finishes.

Since you have a lot of free labor consider interior drain tile. This is cheap and very helpful if your local soil is heavy.

05-03-2007, 10:00 AM   #9
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Quote:
 Originally Posted by concretemasonry You can have all the friends you want help on an ICF foundation, but you should hire at least one person that has the know-how. It is not just like "dumping" wood or metal forms full of too wet concrete. If your forms move, you are dead in the water with a mistkae that will tkae thousdands of \$\$\$s. - When the forms start moving, there is little you can do. The bracing if far more than most people are accustomed to.
I'm beginning to see your point now. Perhaps I'll reconsider-if I can't find someone with a lot of ICF experience.

Quote:
 Originally Posted by concretemasonry Since you have a lot of free labor consider interior drain tile. This is cheap and very helpful if your local soil is heavy.
Do you mean in addition to the exterior system? Is this just a similar system that goes inside the foundation below the slab?

 05-04-2007, 02:10 PM #10 Balchcon   Join Date: May 2007 Location: Kirkland, Illinois Posts: 2 Rewards Points: 10 I am a concrete man and I checked your math and it all seems right. Shawn Balch(Balch Concrete)
05-05-2007, 06:49 AM   #11

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I drew a quick solid model in my cad program and hit "verify properties- volume" then converted from cubic inches to cubic yards.

concretemasonry has legitimate concerns. As a pro he knows how costly a mistake can be. It takes a leap of faith to sink everything you've ever earned and more into something by yourself... but it is extremely gratifying when it works! I stayed away from arx and the like for the same reason and had the pros do my foundation and basment... but then again I had 23 corners in my poor! Although other friends have DIY'd "boxes" with success. I saved the money diying things I had more experience on...framing, kitchens, fixtures, heating, decks, etc. Nice product though, the insualtion and sound deadening is awesome! I was in a house completely in this method. It had trusses and roof sheathing but no finished ceilings and no fascia and or soffit yet and I almost forgot it was right along the highway!

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