Expert: Stephen Major - 6/3/2007

Question
Mr. Major:

I am planning an addition to an existing house.  The existing house is 70  years old and is solidly constructed of masonry block with a brick veneer.  It has a full basement but the main level of the house is about three feet above grade.  

The addition that is planned will be wood-frame addition that will span the entire length of the existing structure (the bearing wall).  A full basement is not planned, simply a stem wall that will create a crawlspace.  My goal is to retain the brick veneer on the existing house as the interior wall of the new space.  Therefore, I do want to build a "second" house that is "next to" the existing house.

My questions are:

Can the addition be attached to the existing structure with ledger boards that are bolted to the existing structure?  

If yes, does the foundation have to form a closed loop?  Or, can the foundation be three-sided?

If no, are there any other options for using the existing exterior wall as a bearing wall for the new structure?

Thanks, John.

Answer
John,

What you are proposing is pretty sound.  Yes, you can bolt a ledger to the existing wall.  The size of the ledger as well as the bolt size and spacing is best determined by an architect or engineer.  I assume you will need to get stamped plans to get a building permit.  If not, you still need to make sure your structure is properly designed.

The foundation can certainly be three-sided.  This is done all the time.  Before you pour the concrete footings be sure the subgrade is solid, undisturbed soil that is well compacted.  Pin the new footing and foundation wall to the existing foundation with rebar, etc.  

Best of luck with this, and let me know if you have any additional questions.

--Steve Major