In need of some experienced opinions please!
I currently have a builder building a home for me on Long Island in NY. The builder dug the hole yesterday, and poured the concrete footings today. Tonight, into tomorrow, we are experiencing a blizzard (10-15 inches of snow)and freezing temps (19 degrees). The builder absolutely refused to cover the footings with insulated blankets, and claimed the calcium he put in the mix was sufficient. The footings are now covered in snow. In addition, he claims that the rest of the foundation (walls, etc) will be poured as soon as the snow is gone, despite cold temperatures. We have begged him to wait until the temps hit 40, but he is refusing. Can someone experienced in concrete please give an opinion as to what we should do? Should we not accept the flawed/compromised foundation and back out? Is pouring below 40 really good? Is it possible the footings are okay despite 10 inches of snow and no cover? Please help!

I agree that you should be concerned about the lack of blanket insulation, and calcium isn't the way to go anyway, as it destroys rebar. There are better, newer additives. This is your house, not his. Concrete goes through changes not just in the first days and weeks but also years.

I assume that you have given him a fair amount of money though. I'd let him know that any future payments will be held by your lawyer while you get more opinions. How about your building inspector?

Okay, so I spoke with the building department regarding the inspection, and alerted them to the fact that he poured, didn't cover, and is planning to pour the walls in the cold. They told me that builders often hide cracks and flaws from the inspectors and that it is very possible it will pass inspection despite the less-than-ideal circumstances under which he poured. We plan to hire our own engineer/inspector to come inspect it in addition to the town inspector, but we are worried because my father claims concrete that has been compromised due to weather, can crack years down the line, and we wouldn't know it right away (at the time of inspection).
Yes, he has some of our money, but he is currently in default of our contract (because inappropriate delays in building), so we have the legal option of back out at any time. Our down payment is in escrow, and the only money he currently has from us, is a moderate amount used to pay for upgrades (tile/granite/etc). We would probably have to sue him for that money if we backed out, but at this point we are most interested in getting the house done right (rather than backing out). Everyone has told us so far the footings should probably be okay because they are less important than the flat pour for the walls. But we can't figure out how to hold him off from pouring the walls. Along the same lines as your advice- we are considering having an engineer write a letter explaining that best industry practice dictates not pouring in cold weather, and sending it along with a letter that says we are not going to accept the foundation if it is poured in cold weather. Perhaps a lawyers letter would be better though...
Do you think the footings are okay? Or should we be extremely concerned about those too (they are already done so that would be a big issue).

Sorry my comment was posted above accidentally.

The letter you suggest from the engineer isn't quite right, because it is possible to pour winter concrete safely - it just costs a lot more in time and money. And you have to watch every step to prove it's being done correctly. Again, calcium is old school and not considered good anymore, so he doesn't sound like the best contractor for the job anyway.

Just tell him to stop and he's not getting paid for anything until this is resolved (or not if not). With the work behind schedule, he doesn't have the right to do what he wants.

Okay, I think I'm getting the general idea. We are speaking with an attorney today about withholding money/backing out/forcing him to wait to pour. Thank you so much for your comments!

One way that could prove difficult for you legally is if you asked for change orders that delayed the beginning of the job. He could conceivably go pour and put a contractor's lien on your deed, and might even win.

My parents went through this in 1967. Everyone sued everyone. The foundation was poured in January; mostly because my mother hired the contractor in the fall and kept making changes. Special order windows and doors were late, leaving the framing and subfloors full of snow. Etc etc etc

Concrete should not be placed on frozen grade and needs to be protected from freezing for a specified period (different specs use various criteria).

In bridge construction in the State Highway Agency I worked for the practice was to protect the area upon which the concrete was to be placed by covering and heating to prevent freezing of the soil foundation. Then uncover long enough to place concrete, recover and keep concrete between 50 and 80 degrees for 7 days.
A minimum of 40 degrees was required within the forms and concrete had to be min. 60 degrees coming out of the mixer truck which was accomplished by use of heated mix water.
The contractor knew all of the requirements because he bid based on the specifications for the work.
You will need to show that your contractor was required to perform work by a specific standard, contract or building code.
My biggest concern so far would be whether the footings were poured on frozen ground. Soil "swells" (called frost heave) when it freezes. It will go back down when the thaws occurs which could result in voids under portions of the footings and could cause settlement or shifting. Just because footings are out of sight certainly doesn't make them less important. Here is an excerpt from the Portland Cement Association (the real experts) regarding cold weather concreting.
Concrete Technology | Frequently Asked Questions (FAQs): Cold-Weather Concreting | Portland Cement Association (PCA)

Hi, I am a poured wall contractor from VA. Your footings should be OK, in my opinion. They should have been covered for sure, but the snow will insulate believe it or not. Since the hole was just dug, geothermal heat from the earth will also help. Your walls are another item. Mix design is important here, more so than ambient air temps. With the proper mix and planning we can pour into the low 20's at night. Below 27 he should cover to be safe, below 25 think about a heated enclosure... nothing to fancy, heaters and a tarp work just fine. Below 20.. not a good idea, if you can wait. The absolute most important thing here is the mix is not wet down too much on site, this delays early strength gains which is what you want here... high early strength. Keep in mind the first 3 nights apply to the temperatures above. You must remember though, your clock is ticking, you have to get this foundation done asap as freezing the earth below your footings is a concern as well. I have seen recent studies of walls poured and air temps not above freezing for a month, the good mix designs all achieved design strength. Keep in mind though as you choose to have houses built at this time of year, these concerns are sure to happen. Many contractors bid work in warmer weather, then as cold sets in, might ask for the customer to share the cost. Remember, quality work is not cheap work, low bidders do not allow for heated enclosures. Good luck to you!

I just wanted to add to my last answer. I think you will definitely have to become more involved with your building process. Talk to the concrete supplier, they should have good winter recommendations, as they can't have a bunch of frozen concrete either, bad for their business. Covering that footer should have been done and would not have been expensive, plastic and straw would have worked, although you should be OK. Some of the other posts are right on. Concrete at the time of pour should be 60. Hard to do if you are far from the plant though. One thing that can help offset this are going to a higher strength (psi)concrete. Accelerators are a must. Calcium chloride is kind of the residential standard, but can steel can be degraded by the chlorides. Non chlorides do not hurt steel, but are about twice the cost. In my opinions you have to use accelerator, non chloride is better, but at a cost. Our winter mix is 3500 psi (4000 better but hard to handle), reduced flyash content, 1-2% accelerator(non chloride for ftgs and walls and calcium for fiber reinforced slabs), 6% air entrainment, hot water, 5" slump max. Long story short, we have poured walls through the winters for 10 years and along the way mixes have gotten better as has our knowledge. I have never had a problem with any wall we have done, even though I take more precautions now than I did when I first started. Final note.. document things, ask for batch tickets, record your weather conditions, send certified mail of concerns/requests, email is better than phone calls, take pictures of coverings or lack of, hire third party inspectors if you're really concerned.

We are doing all of that, hiring inspectors, etc. we are now going through an atty to deal w/ this because the builder will not wait until proper conditions, and refuses to cover the concrete. I appreciate all of the advice.

Back again...
All this can be confusing for about 3 reasons:
One is that residential doesn't have the same requirements as commercial or highway because the load of a typical house is minimal.
Another is that the technology is constantly changing, and you have old school and new.
And third, all the data isn't in on the new, and there are going to be differing opinions, and there are other variables, such as soil type, ground water, drainage and waterproofing. (One of our piers holding up the carport sank 10" after 40 years, while the 2 around it were fine. Lots of water collected in that spot.)
Our 1967 foundation, poured in winter probably with just calcium chloride, hot water and more curing time, no modern additives or blankets or thawing the ground, has been OK; 2 minor cracks and one separation at the slab for about 3', fairly typical and easily fixed with epoxy. Excavating has revealed that 95% of the waterproofing is gone and the drainage pipes are totally clogged and useless, and downspouts run underground clogged too. Concrete is porous and isn't expected to keep water out on it's own; it's job is to hold up the house. You should have specified a footing drainage system that is wrapped in filter cloth around gravel and pipe, and a dimpled membrane over the waterproofing. This all comes under 'new' approaches to proper drainage. Then there's insulation, which people don't agree on. Some say it should be outside and some in. A new idea is to put it flat on the ground around the foundation, about 2' down, to hold in geothermal heat. (This is the foam stuff, sold in blue or pink in various thicknesses.) These are all topics at least as important as winter concrete.

Of course any contractor wants to do winter jobs to make a living, and it has it's advantages for the client. But they need to still do it right.

Concrete contrater in ontario 10 inches of snow will protect footings better then your insulating blanckets for a longer period,remember insulation works both ways it keeps cold in and out