Portable Garages and more from MDM Shelters, a website of MDM Products, LLC, formerly Shelter King. For an instant garage or other temporary structure, MDM is a source for your portable garage, party tents, boat canopies, motorcycle covers and other applications of high quality tension fabric buildings..Ft garage door is the size that is suitable for you who have a oversized garage. Usually ft door used to accommodate two vehicles in the garage. There are .Double Garage Door Sizes. As it concerns double garage door sizes, the standard doors have measurements of feet, feet and feet..If you plan to replace your existing door, do not justume it must be some standard size. There are some standard garage door sizes, but there are also plenty of exceptions..