Expert: Dan Griffin - 6/27/2011

Question
I just had an inground pool put in.  I am having the concrete patio around the pool put in next.  They are putting in 3 feet of concrete all around the pool except on one side of the pool I have it extended out to 10 feet.  They put in rebar for reinforcement in only the first 3 feet of that side.  They tell me they will put in concrete piers for support in the rest.  What is your opinion of this?  would it not be better to have rebar within the entire patio? how will it affect the structural integrity if part of the patio has rebar and the other part is supported by concrete piers?

Answer
Diane, on concrete flat work that is only a nominal 4" thick rebar does little to add to the strength.  The important factor on any slab on grade is proper subgrade compaction and preparation.  The next most important consideration is proper jointing to deal with shrinkage cracking.  Too many joints are better than having cracks - of course, the joints will need to be sealed and maintained.

I would think that for the dollars being spent and the good will, that the contractor would be more than happy to give you the rebar for your peace of mind.  It is a minimal cost.  I suspect that the 3 floot rebar has more to do with maintaining the joint with the pool to prevent the sidewalk settling at the pool.  The need for piers would imply that the contractor is concerned about fill settling or soil erosion problems.

Proper joints, proper curing, attention to subgrade, and well bonded finish with Cool Deck or similar would be the things I would want my concrete man to discuss with me and have ready answers.