I’m very sorry to hear about your window troubles. Not only is this bad for you, but it’s a sad and all-too common example of the deplorable condition of the construction and renovation trades in Canada. Anyone is free to call themselves a renovator, and many unskilled, unprincipled people do. If you’re feeling air coming in around your windows at this time of year, then the installation is clearly faulty. The situation will become unbearable in winter, not to mention the rotting of your wall frame that you quite rightly fear. Your first step is to approach the contractor with your concerns. Keep me posted on how things go. If he doesn’t respond with a re-installation of properly sized windows, let me know. A little public exposure does wonders for helping people do the right thing. If you had to do it all over again, choosing an installer certified by Window Wise (800-813-9616) would have taken all the guess work out of the job.