If you need more space in your ranch house, I highly recommend looking around for it inside the existing walls first. If any portion of your basement is un-finished, if your kitchen is fully closed off from the house or if you have a three season room connecting your house to the garage, any of those spaces should be your first move in a remodel.
However, it is relatively easy to put an addition on to a ranch style house. In fact, they were designed with just that idea in mind. In their history of ranch development Conolly and Wasserman describe it this way:
“Ranch house were designed to be built in stages, as the owners could afford to or when additional children necessitated more space. Many ranch homes started out as simple rectangles and evolved into a veritable alphabet soup of options as an extra leg or two was added to form an “L” or an “H” shape.”
From Updating Ranches: Design ideas for Renovating, Remodeling and Building New
This is easily demonstrated with a quick view of Google Maps satelite imagery. When this neighborhood was built, each home was a slight variant on a 28′ x 40′ rectangle of house with an additional 24′ x 12′ single car garage either attached or nearby. They all had the same rough interior layout: kitchen, dining and living area to one side, family bath and 2-3 bedrooms to the other.
The fly over view shows a few untouched examples of this layout … and countless variations of L, U, and Z shaped additions projecting out. Garages were expanded, living areas and master bedrooms added off the back, breezeways converted into 3 season deck additions and the list goes on.
The sturdy construction, simple roof line and single story setup make it easy to add a rectangular form to a ranch in any direction allowed within the lot lines. I think the best effect can be achieved by pushing out to the back to add either a more generous master suite or a back-yard-connecting family space but the possibilities are nearly infinite.