I have a mud room that I'd like to make larger. By doing so I have to extend the floor out into the garage. Currently, there is a landing in the garage that is about 3 feet off the ground leading into the mud room. I want to remove the landing and wall/door leading into the mudroom and extending the floor into the garage by about 4 feet and adding non-load bearing walls to the new extension. Since the current walls in garage on top of the foundation, I need to find a way to support the new extended floor/walls. I'm looking for help on how to support a floor that will be about 3 feet off the ground.