I am building a garage. I am ready to install the entry doors, I have 3. I need to know the best way to seal the threshold to the concrete floor. 2 enter directly to the garage and the 3rd will enter into a hair salon for my wife which we will be putting down some sort of finish flooring product not yet decided on. They all have aluminum thresholds. I live in South Dakota, the winters can get pretty cold. I don't know if that will make any difference. Have considered just silicone but I am wondering if there is a better product out there. Thanks.