Need a quick answer. Does anyone know...

[William J. Decker]

Does anyone know what the guidelines or IRC codes are for the amount of time that concrete foundation forms must be kept on?

Foundation walls are 8' 10" and the foundation wall is 10" thick. They poured yesterday morning and the forms were taken off this afternoon.

Doing a phased inspection for a contractor (go figure! ). They want me to check the site out, prepare an ongoing report and do a final, pre listing inspection.

Here are some details and pictures. Please comment as you see fit.

NACHI helps.

Little Indian (eastern, not American) woman whose husband has WAY too much money and was a builder (money guy only) and built some pretty decent tear-down McMansions. The husband has gotten out of the business, but the wife likes it. (Around here, the Indo-Pak community is very big.)

She "built" her first house (She is the GC) and had me look at it (spec house) and she ran into many problems (she hired the cheapest subs. Go figure.)

Now, she wants me to "inspect" (read, check out and report how well the subs are doing and correct (or fire) them depending or their work.

You have to understand that the codies in this area (northern Chicago sububs) are usually good, professiona guys, but they have very little time on site (an average 4,200 SF SFH has only about 45 minutes, total, of local code inspector time on site during the whole process).

Footings were poured (with 2 x 6 forms and the concrete only went down about 7 to 8 inches). I never got a chance to check the rebar in the footing (duely disclaimed). The keyway was formed with steel angle irons, dragged through the wet cement (only 1 1/4" deep and in a V form. Picture 1.)

Then they put up the forms (about 3 days after the footings were poured). Please note the rebar (only at the bottom of the forms) which were tied with old, rusted wire. (Picture 2).

Drain tiles were just flexable black perf, not shedule 40 PVC. Seems like they want to claim both interior and external drain tiles, but the just run them through the footings, depending on the perimeter (many in and outs). (Picture 3, outside corner in an indentation.)

The concrete was poured yesterday morning, but was still wet and "could easily syill write my name in the top" on yesterday, early evening (pciture 4).

There was a garage (less deep footings and foundation) at the front east, and a basement walkout on the east side. The footings for these areas had no protruging rebar (for marriage into the adjacent foundation wall). There erre also big gaps, and embedded wood (from forms) at the basement walkout interfaces with the higher footings and foundation walls.

Please answer the "how long before you can remove the forms" question first, then, any comments?

[William J. Decker]

Sorry. Hit the 5 picture max limit. Here are the other pictures.

[Michael R. Boyett]

Here's some food for thought from the American Concrete Institute:

ACI 347-04, “Guide to Formwork for Concrete,” Section 3.7.1, gives direction regarding who is responsible for determining when the form stripping operation can begin: “Although the contractor is generally responsible for design, construction, and safety of formwork, criteria for removal of forms or shores should be specified by the engineer/architect.”

As stated in ACI SP-4, Formwork for Concrete:
“Since early form removal is usually desirable so that forms can be reused, a reliable basis for determining the earliest proper stripping time is necessary. When forms are stripped, there must be no excessive deflection or distortion and no evidence of cracking or other damage to the concrete, due either to removal of support or to the stripping operation. Supporting forms and shores must not be removed from beams, floors, and walls until these structural units are strong enough to carry their own weight and any approved superimposed load, unless provision has been made to allow for anticipated temporary construction loads, as for example in multistory work. In no case should forms and shores be removed from horizontal members before concrete has reached the strength specified by the engineer/architect for form removal.”

[Brian E. Kelly]

http://www.concrete.org/FAQ/afmviewfaq.asp?faqid=28

You are good Michael

[William J. Decker]

Originally Posted by mboyett

Here's some food for thought from the American Concrete Institute:

Thanks. Good advice (spread the liability to the subs ).

Also, please note. The soil was compressable clay.

[William J. Decker]

Originally Posted by bkelly2

http://www.concrete.org/FAQ/afmviewfaq.asp?faqid=28

You are good Michael

You too, Brian.

Mike always tries to be the hero

[David P. Valley]

I've never been in the foundation pour business, but I do know that all poured concrete must be given time to cure. IMO...24 hours is too early to remove forms.

During the curing period, the concrete surface should be kept wet down by repeated hosing with a fine mist. Such a hosing down process should be done at least twice during any 24 hour period for about three days. Then the forms can be removed.

[Michael R. Boyett]

Originally Posted by wdecker

Mike always tries to be the hero

My Googler was just running at top speed today that's all.

[ldapkus]

Will,
Is that the contractor I referred to you a couple of weeks ago?

[Bob Elliott]

Yeah basic 101 is the longer it is kept wet. the better the concrete.
Same with plaster.The slower the cure the better.

[jbettencourt]

William, I have been working in residential and commercial poured concrete foundations for 7 years now and on most residential work the forms will be removed the following day should be fine if the concrete is a proper mix and not watered down. I am working on a large commercial project right now where we did one of the pours yesterday walls are 10' high 12''thick with double mat rebar to the top , poured 90 cubic meters ( yards for the americans) of concrete yesterday afternoon and spent today removing the forms.

Sorry William I just reviewed the pictures, there are a couple of things that bother me. The wood imbeded in the wall is an incorrect method of closing the forming gap at the step, it should be closed on the outside of the form ensuring that concrete fills right to the step and not leaving an open gap. Also the footing at the step should not end at the top and the start again at the bottom. The framing should come out past the step so the concrete extends out past the step and joins the lower footing, the engineers and inspectors up here would never let us do it the way it is pictured. Hope this helps, if you want any more info send me a PM I will try to help.

[Mario A. Kyriacou, CHI]

Here is an interesting article.

[Frank J. Carey]

I have to agree with Jerry. I would be more concerned with some of the other issues. If they had the proper mix this time of the year in the climate that we share (not very nice), then the concrete should be fine. I would be more concerned with what Jerry stated and the drain tile not being pvc. When do they intend on starting the deck for the first floor?

[Brian A. MacNeish]

CSA document I read many years ago recommended 72 hours for forms to be in place with exposed surfaces to be covered with burlap and wetted when necessaery. When I tested concrete for the NB Dept of highways, three days was requied also. The concrete forming company had to have someone come back to the site on weekends to wet the burlap.

[William J. Decker]

Originally Posted by ldapkus

Will,
Is that the contractor I referred to you a couple of weeks ago?

No. At least I don't think so. Call me.