Mercer Island Garage Doors. Garage doors are true modern marvels. They are the defenders of all the belongings we have stored in our garages. When we think about the effect that our garage doors have on our home life, we realize just how much we rely on our trusty old garage door. Mercer Island Garage Doors is interested in one thing, and one thing only: Keeping your garage door working as good as new, throughout the years. We specialize in everything you may need for your garage door, especial garage door repairs, in order to keep the outside of your home beautiful.