Pouring a foundation during the winter??

Hi,
We are also planning to begin construction this winter in the Pacific NW. From my research the "precast foundation systems" look very interesting - only I can't find anyone around here who does them. They are especially designed for basement use. I like the idea because you don't have to worry about weather and you can begin framing the next day after they are set into place. One day for the foundation - makes a difference if you are paying on a construction loan. Anyway, I got the link from this (bobvila.com) website. It is superiorwalls.com. Good luck. Linda

It would matter A LOT when a foundation was poured in St Louis.

Not only would concrete to be poured in winter cost more (because of additivies to keep form freezing)...special precautions would need to be taken to keep the soil warm to keep from freezing and heaving during pour and curing.

The bottom line is:

You CAN pour a foundation in winter in St Louis, but it will cost you substantially MORE to do so to protect the foundation from any ill effects from cold weather.

For that reason, most will choose to wait till spring when temps won't matter and costs will be lower.

Costs aaside, the biggest problem in terms of quality is making sure the ground does not freeze under the 'crete while working and untill backfill is done and th efloor system is on. Otherwise, the soils will move under it and cause settling and cracking

I have a similar problem, Please see the inquiry I posted as well as the advice I received.
I hope this helps you as it has helped me.

Bob Vila
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Question Posted
I need some advice on our foundation repair. We are having our faulty foundation repaired, the Staten Island NY home was built in the 1950's and the foundation was formed with beach sand/mud in the concrete mixture. Well now it is crumbling below us and my architect was shocked to see the foundation in such bad condition. He had never seen this type of foundation. I have a contractor. However, I wish to get a second opinion about the process of rebuilding ,extending and repairing parts of the foundation. The part that they have to rebuild as well as the new extended part of the foundation I want to verify at what is the lowest recommended temperature they can pour any foundation mix and be sure it will set and cure properly, without having a problem with it, other than reasonable maintenance issues 1 to 10 years. My contractor guarantees their work but how long can they guarantee their work for. Also I heard about new forms they use to build foundations on one of the home improvement shows and that they are insulated to be used in negative degree temperatures. Is that fact or fiction. If it is fact, I want to advise my contractor.
Thank you for your advice.

Answer posted by
Glenn Good www.consultationdirect.com
Moderator on Bob Vila's bulletin board

It is true that concrete can be poured during cold weather. The main thing is to keep the concrete from freezing. There are insulated concrete blankets that can be used to hold the heat in the concrete. (Polystyrene foam board insulation can also be used.) Concrete creates some heat of it's own as it cures and if insulation is used to keep the cold away from it should cure fine.

It is recommended to keep concrete above 40 degrees. With the proper insulation covering all areas exposed to the cold it will maintain this temperature in most cases. Keep in mind that this insulation must extend below the frost line as well. Rigid polystyrene foam insulation board can be used below the grade and left in place. The warmer the weather the less insulation required.

It is also important to keep the moisture in the concrete as it cures. To do this you can cover it with polyethylene and seal or tape all joints, or spray it with a heavy coat of concrete sealing compound such as "Cure and Seal". Freezing and rapid drying are the 2 main problems you need to be concerned about.

You may also want to try to keep track of is the amount of water in the concrete and the time it is poured. Concrete should be placed within 1 hour after it leaves the plant. The "slump" test is used to determine the amount of liquid in the concrete. Concrete should not be poured over a 4" slump. The lower the slump the less water in the mix and the stronger the concrete will be. Excess amounts of water cause the concrete to shrink more as it cures and as a result stress cracks will begin to form and weaken it.

Another item I should mention is the addition of calcium to the mix. This is often used in cold weather pours to accelerate the curing time and prevent freezing. The one major draw back with using calcium (and many other accelerators) is they have a tendency to deteriorate or oxidize (rust) the reinforcing steel that is used in the concrete. Chances are you will have steel rebar in your foundation and I would advise you do not permit the use of accelerators in the concrete mix. This will mean they will HAVE to use insulation to protect the concrete from freezing but you will get a stronger product that will last longer.

I hope this helps,
Glenn Good www.consultationdirect.com
Moderator on Bob Vila's bulletin board
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