Introduction

Have you noticed that there are more and more houses being lifted, for the creation of an addition beneath an existing residence?  At least in the SF Bay Area, there seem to be a lot more 'Building Beneath' projects than in previous decades.  The number of projects that include building beneath, either through raising a house or excavating (or a combination of both), has been rising steadily, though nowadays everything seems slow.  I teach a class on this way of adding to your house at the Building Education Center and am quite interested in this approach.

It seems one of the main reasons this has become more popular is that the structural code restrictions have been getting steadily more stringent in the Bay Area.  Where once we might easily have put an addition on top of an existing house, to do so now requires much more, structurally.  Many walls and most of the foundation below such an addition must be considered carefully and strengthened to suit.  In contrast, if your addition is below the existing house, only the new walls have to meet code.

The corresponding foundation, of course, must also be strengthened, but often the entire foundation is in need of replacement anyway, and many times this is the original impetus that impels potential clients into my office to discuss such an addition in the first place.  Some houses in the Bay Area are still on brick foundations!  These have to be replaced even when building on top or converting an attic..