Window install - in middle of winter - cons?

I have a 2-story 40 year old home that still has all of its original wood windows. I am planning on getting them all replaced with new double or triple pane windows in order to improve energy efficiency (even with the windows shut you can see the curtains blow when its windy).
There was an advertisement on the radio back in February by a local window company saying that they replace windows in the middle of winter with 50% off of the labor costs. This sounds pretty good to me given the amount of windows that I'll need to replace.
Now here's the catch. I live in Ottawa (Canada) where the weather probably averages -15 Celsius (5 Fahrenheit) during winter, without the wind chill. During extreme cold spells the weather can drop below -45 Celsius (-49 Fahrenheit) with the wind chill. Hence why the company is advertising 50% off labor costs for window replacements during Winter. It can get pretty damn cold! :)
In your opinion would there be any disadvantage to getting the windows replaced during Winter, given the temperatures? Would the results be the same as getting them replaced in the Summer? (i.e. a nice tight seal). The only one that I could think of is if they need to do any caulking, it may not work properly if its that cold, or that if its really cold outside that the installers might try to do the job as fast as possible to get back inside and warm up, thus rushing through the job and not doing it properly.
Is having your windows replaced in the middle of winter a bad idea? Has anybody gone through this before?
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It could be a good deal. Also depends on just what they are doing. Many years ago I used to install replacement windows in a little sideline business that I had. All the work was done from inside the house. It was a little uncomfortable at times, but the opening was only open for about 10 to 15 minutes per window. You can close the door to a particular room to save on heat.
Talk to them as far as exactly what they will do, how long it will take. Not much downside that I know of. New construction goes on year round in most places today. Ed
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I would not anyone work on my house doing windows in that temp. You will have rushed work, you cant caulk, my windows were done in fall and the warmth, some were gone 5 hrs due to problems.
A rushed job can mean a bad job and if not leveled, plumb, and squared to less than factory warranty maximums you will loose Any warranty you may have had. Many warranties give 1/8" max or you have no warrany . My hack redid 4. Luckily it was warm out.
In those temps you will loose your heat savings for that month maybe costing your savings. Weigh the costs you may not save but loose.
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jonny snipped-for-privacy@hotmail.com (Jonny R) wrote:

My sister had hers done in Dec. in St. John's NF. she said it was nbd (no big deal). As far as I know, she has had no complaints about the job.
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