Expert: Roger Zona - 8/18/2008

Question
QUESTION: I want to build a low 3-sided wall out of cinder blocks only two rows high to serve as a planter box, with the cinder block wall of my garage as the fourth wall.  My question is, do I need a footer or other surface (such as a poured slab) since this will be such a low wall (only two rows high with cap stones) or will dry stacking or mortaring be enough?  I was planning on not pouring a slab, just building a wall with the dirt expose to allow for draining.  Thank you!

ANSWER: Craig,

You didn't say in what climate area the planter area is to be built. Weather conditions call for different sollutions.  I am in Florida and we "dry stack" landscape bricks or blocks for areas attached to a house.  If the planter were to be free standing, then a foundation is recommended.  No slab is necessary and you want good drainage.  Contact a landscaping expert to ask about preparing the soil for your planter.  Again, soil condtions will vary from area to area and you want the optimum condtions for best growth and maintenance.  

Cinder blocks are not the most attractive materials you could use.  There are landscape blocks made especially for stacking.  They are not 8" high so you may need four rows instead of 2 rows.  These blocks have a taper from front to back so you can make a curved line.  I would not recommend mortaring or the blocks.

Hope this has been helpful.

Roger



---------- FOLLOW-UP ----------

QUESTION: I apologize for not including my locale, I  realized after I submitted it that that would have been helpful.  I am in Indiana, across the river from Louisville, KY.  The reason I am intending to use cinder block is that the fourth wall I will be placing this against is already a cinder block wall (part of a garage) and wanted consistency of color and appearance.  I know it's a strictly utilitarian look, however in this particular locale that is the look I am going for.  I have other locations I am working with more decorative blocks for a more aesthetically pleasing look.  Thank you for your information!

Answer
Craig,

Your logic makes perfect sense.  I suspect your winters are rather mild and the freeze is not too deep.  You will probably be safe without a foundation.  If you wish, just as a safety precaution, you could dig below grade and lay a cinder block (concrete block) in the opposite direction of the wall block and have a foundation of sorts.  No mortar would be necessary and the open cores of the blocks will allow drainage.  

Good luck

Roger