Winter foundation / basement pouring

My wife and I are about to build out new home. Its rather expensive and we have every intention of making this our last move. I subcontracted my last home when land was still available to the general populace.  Now however, I am have no choice but to have someone do it for me.

My concern is its near mid November here in Michigan. I have expressed a great deal of concern to my builder about my desire for a NON WINTER foundation/basement pour. He assures me I have nothing to worry about and this is actually the best time. My experience with this is my sisters home, who I had warned about a winter pour. She pleaded as I have done with my builder to postpone till spring. They poured anyway.

The result was 10+ MAJOR cracks and leaks, resulting in MAJOR mess and dust throughout on numerous occasions (3).
Can you comment on winter pours ? What to look for, what would you do ?

Can you point me to some areas I can learn more about it ? Am I having chest pains for nothing ?
You wrote:

"My concern is its near mid November here in Michigan. I have expressed a great deal of concern to my builder about my desire for a NON WINTER foundation/basement pour. He assures me I have nothing to worry about and this is actually the best time."

I would not say that! But there is no reason why they cannot do a good job if they follow the correct practice.

"My experience with this is my sisters home, who I had warned about a winter pour. She pleaded as I have done with my builder to postpone till spring. They poured anyway. The result was 10+ MAJOR cracks and leaks, resulting in MAJOR mess and dust throughout on numerous occasions (3)."

The cracks were probably not the result of freezing alone, but the dusting sounds like it was.

A few points:

  • I expect that in your area the good contractors know how to pour concrete under these conditions, but maybe not...
  • The building department may be a good place to inquire about their recommendations regarding concrete practice and inspections.
  • For information on placing concrete under freezing conditions the best source is the "American Concrete Institute" which is based in Detroit. They have publications that teach contractors (and homeowners) on the correct practice for any situation. Try calling 313-532-2600 and ask them. Their publications are used as part of building codes by many cities. These can be found in most engineering libraries.
  • Another excellent source is the "Concrete Construction" magazine based in Chicago. They have excellent articles on these subjects. Try calling 708-543-0870.

As for what to look for:

  • Concrete hardens through chemical reactions. These stop when it freezes and as a result it remains weak longer.
  • Water that freeze inside the concrete as it hardens make it porous and weaker. One of the results is dusty surface as you observed.
  • The main problem occurs when concrete freezes in the first few days. After that it is strong enough and generates enough heat (from chemical reactions) to harden fine.

The main points to look for:

  • Do not pour concrete in freezing temperature or if you expect freezing to start soon (hours).
  • Soon after pouring (few hours - when it is dry enough to sustain walking) cover it with blankets (burlap; tarp; hay; sand...) to insulate it from freezing air and let its internal heat keep it warm.
  • Keep it covered for at least a week if temperatures are low. However, practice in your area may be different but still effective.
Thanks for that very timely comeback, I really appreciate your time and will certainly run down your leads for information. I will let you know what happens. Should I be concerned about the #bags in the mix ? Any additives they may use - calcium chloride ? What about this stuff the Army used for sub-freezing concrete pours ?

Would you mind if I forward you the details when I get this from my builder ? Any points I could put in a legal document for them to sign ?

Again, I appreciate your time.
>Should I be concerned about the #bags in the mix ?

Not really. The mix design is probably done by a ready-mix supplier who knows what he does. Just make sure they use the correct specified strength (2000-3000 psi for foundations) and the number of bags will be a function of that.

> Any additives they may use - calcium chloride ?

Calcium chloride accelerates hardening and may help avoid early freezing damage. If used conservatively by someone who knows not to use too much it can help.

>What about this stuff the Army used for sub-freezing concrete pours ?

I am not sure what you are referring to. I doubt that your situation calls for such drastic measures and the local contractor probably is not that sophisticated. You can wait for a nicer day...

>Would you mind if I forward you the details when I get this from my builder ? Any points I could put in a legal document for them to sign ?

No, by all means do let me know.

Sorry, I do not give legal advise. I believe that any contract which requires satisfactory concrete will suffice.
[I found you through] AltaVista, searched on concrete, cold etc. Your resume showed up and I thought I hit gold - I did. I really appreciate your time and will certainly let you know what happens. If I have a problem, I would love to send you a core for analysis. I know I sound paranoid, however its the last house I intend to build.. Again - thanks for your prompt, courteous, concerned response.