Expert: Bruce E. Johnson - 11/19/2009

Question
Hi Bruce,

I recently moved into a home with a little shed in the back.  The old shed sits on a 15 x 15 foot brick foundation.  But the brick foundation is not on a concrete slab, just dirt.  The existing shed is in, essence, a lean to.  One of the four sides of this brick foundation has a 5 foot tall brick wall which serves as a retaining wall.  So basically I have torn down all the rotten lumber and now have a 15x15 brick foundation with a single 5 foot brick wall serving as nothing more than a retaining wall.  Well, I'm looking to build a shed on this foundation.  Nothing complex, just four walls and a roof.  My question is this:  Do I leave the brick retaining wall and simply frame up from the top ledge of this wall.  Or do I build a free standing shed that simply sits adjacent to this retaining wall?  Essentially, do I use that free standing brick wall or not?  My other question is this:  How do I mount my footplates for each wall on a brick foundation that contains no concrete below it?  Should I pull up a few bricks and place 6x6 posts in the ground as the corners of the building?

Thanks so much Bruce, sorry for the long post.  Just lots of confusion with this project.

I appreciate your insight

Answer
Hi Grady, I've read this question several times over the last couple days trying to figure it out.  A lot of mystery surrounds the words "foundation" and "brick"..
When you say 15x15 foot brick foundation, to me you are saying you have a 15x15 foot brick patio or floor which will not support a structure.  A foundation will be deep and solid, generally concrete and capable of supporting not only the load of the building but also be anchored into the ground with enough ballast/ weight to prevent the building from uplifting during wind or other weather events.  The word brick refers to a standard 2.5 x 3.5 x 7.5 inch fired clay brick.  Is this what you are calling brick?  Or are you referring to a 7.5x7.5x15.5 inch concrete masonry unit commonly referred to as a "block" or "cinder block"?  Brick, by itself doesn't make a good retaining wall unless it is several brick thick and reinforced with vertical steel..If the brick retaining wall is properly built and showing no signs of rupture or failure you can put a wood wall on top of it by drilling into the masonry and using a Simpson epoxy bolt and epoxy install a bolt that, when the epoxy is cured, can be tightened down to a mudsill or bottom plate of a wall.  If the perimeter of your brick floor has a thickened edge of concrete or is supported around the perimeter by a footing you can do the same with the exterior walls, epoxy anchor them to the perimeter.  Otherwise you may need to add a concrete strip footing around the perimeter for proper anchorage.  I hope this information helps, please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com