Frozen concrete footer, still building 1

[skippyzz]

My wife and I are building a new house with a local builder in Ohio. The concrete footer was poured before a very cold weather spell with only 3-5" of straw cover as protection. Vertical core samples in the exposed 4" of footer beside the basement wall after 35 days came back just below 1300 psi and code requires 2500 psi. However, this was discovered after the footer and foundation (poured concrete, horizontal rebar 2' from top & bottom) wall had passed inspection, thus the rest of the house continued construction. The basement floor has not yet been poured, the local inspectors are aware, had a meeting and it was decided that horizontal borings would test the concrete strength directly below the wall. Those borings (taken more than 60 days after placement) came back just below 1800 psi, now the builder wants a meeting with the head code compliance officer to discuss their position. I believe their position is that since other jurisdictions allow the foundation wall to be placed atop a crushed gravel base, the low compressive strength of the footer is still sufficient to handle the load of the house. The clay soil is rated at or above 2000 psf. My question is has this been encountered previously by anyone? Is the footer sufficient to withstand the load over time? What were/are the potential fixes to move forward (the house is under roof and mechanicals are nearly complete)? If this was your house what would you do?? Thanks,
Skippyzz

 

[Rjeffery]

First, Hire a lawyer.

I would make the contractor pay for the all the testing (coreing), then ask for a reduction of the total cost for the out of specification footing. (providing the code officials accept the footing.)

Finally I would insist that the warrantee extend for 25 years (or more) and that the warrantee be able to be passed on to any new owner.

In the 20/20 hindsite department: Hire an engineer or an (shudder) architect to develop the contract and specifications, next time.

 

[dik]

You may want to leave it with the Code Officials to determine the outcome, advising them that they are responsible for the decision. They are the experts, you are the lowly homeowner... let them and the contractor 'duke it out...'

Alternatively, have the contractor provide an engineering report saying it's OK... or better yet, have the contractor compensate you for the cost of your report. If your consultant, let the contractor know that you will be 'bound' by the results of this report... If the contractor's engineer, then reserve this option.

Cost of all testing should be borne by the contractor.

Asking for compensation for the mistake will likely reach an impasse; the contractor has already suffered financially. If the matter goes to the lawyers then seek compensation and/or remedy.

 

[boo1]

Current winter concreting practice has remained unchanged for many years. Concrete ingredients must be heated to melt all ice and to create a mixture temperature that is well above freezing; the substrate on which fresh concrete is placed must be thawed; and the concrete must be kept warm and moist long enough to ensure adequate strength development. According to ACI 306, once concrete has attained a compressive strength of 500 psi (3.4 MPa), it can resist one freezing event. At 3500 psi (24 MPa) concrete is able to resist multiple cycles of freezing and thawing.


Deterioration of concrete from freeze thaw actions may occur when the concrete is critically saturated, which is when approximately 91% of its pores are filled with water. When water freezes to ice it occupies 9% more volume than that of water. If there is no space for this volume expansion in a porous, water containing material like concrete, freezing may cause distress in the concrete. Distress to critically saturated concrete from freezing and thawing will commence with the first freeze-thaw cycle and will continue throughout successive winter seasons resulting in repeated loss of concrete surface.

You have a footing that does not meet code and probably your drawing requirements. The real question is, wil it support the structure? At this stage I recommend an Professional Engineer to evaluate if the existing footing condition suports your loads. The engineer (hired by you)should:

1. Field examination of the structure
2. Review core strenght reports
3. Order soil bearing capacity test
4. Evaluation of raw materials and production data and methods - if available
5. Conduct load analysis to determine actual requirements
6. Summarize with recommendation

Inform the builder of this plan, and team with him for a win/ win outcome.

 

[tamu]

I am really surprised & shocked to know such problems so often in advanced countries where contractors know law (layer sui for small small neglegency)and client also try to appoint competent agency to do right job.Then how come such incidents are happening ??

 

[RDK]

First get a lawyer then get a local concrete engineer to do a full testing procedure and report. Don’t pay the contractor any more money. If necessary put any payments otherwise due into the lawyer’s trust account.

Cold weather concrete work is common in Canada. I have poured concrete successfully at –38C. Its not rocket science; all you have to do is keep the stuff from freezing. Insulated tarps, preheating of the water and aggregate, full enclosures and, for mild frost, straw has all been successfully used.

Do you know how cold the concrete was? 3-5 “ of straw combined with the heat of hydration might protect against what you may consider very cold. We will commonly use that for temperatures as low as –5C overnight provided it warms up in the daytime. All that is required is that the concrete does not freeze. The Canadian code suggests that 7Mpa (about 1000 psi) is sufficient to resist early frost damage. Concrete actually freezes around –2C

Depending on how cold and for how long, I would suspect that there might be something else like a bad batch or mix design that is lowering the strengths. The cement content can be analyzed to determine if the mix should have been capable of reaching the required strength.

Forget the 60-day strength. Concrete is specified at 28-day strengths and the continuing strength gains after that are already factored into the designs. Concrete strength is also important for reasons other than the actual compressive strength of the concrete. Crack control and durability are related to strength. Even if the design can get away with a lower strength, the codes are usually based on a strength that performs acceptably in compression, tension, durability and shrinkage.

Forget about putting your faith in the building code people. They may or may not be competent professionals. They also will not be putting anything on the line. Where I live, you cannot sue the local building inspection branch for anything. They make a bad decision and you pay the price. I have done a lot of residential inspections where I’ve seen things that that were passed and posed a significant threat to the structure.

Put the onus for this where it belongs, squarely on the contractor. Do not accept any half-baked fixes. Do not accept a reduction in price. Everyone else will go away and you will be left with the problems in the long term. Removal and replacement may be the only viable option.

Good luck



Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[sc]

tamu,

Welcome to the world of construction where anything can and will occur if you take your eye of a job for long enough. That is why it is always good practice to have someone suitably qualified to supervise the works.

As for the advanced country comments all it means is that the criminals are smarter.



Regards

sc

 

[gp238]

I currently facing a situtation very simillar to you. I had a basement foundation poured for a new house on December 14th at Amherst, New York. . The high and low temperatures on that day were 32 and 20 degree. The high & low tempreatures on the next day were 40 and 24. The tempreatures scince then have been below freezing. After 7 days I tested the concrete strength of the wall by a Swiss rebound hammer. I tested at least at 20 different points and the correlated compressive strength was 1000-1200 psi. Also, when I tapped the surface of the wall by a small hammer it left a dent on the wall. I am very worried about the basement wall and hesitant to let the builder start framing. Could you please inform me as to what happened in your case.
Thanks!
te

 

[Ron]

RDK has nailed it. Don't depend on the code officials...they are usually absolved of liability for their decisions, so don't think you'll get anything there.

Rick's advice is excellent...follow it.

ps...it is a "footing" not a "footer".