Expert: Bruce E. Johnson - 4/6/2011

Question
Bruce,

Would appreciate your advice.

I am in the Los Angeles area. Need to cover a part of the backyard in my townhouse in concrete. It's about 120 sq ft, 3" thick.

Could you please advise me on what are the parts of the job and labor, and possibly what the costs are of each part.

Thank you for your time.

Answer
Hi BK, I don't know why you only want to go 3" thick on your slab but 4" is considered the nominal depth of patio concrete.  A patio in a backyard requires the following: 1. the grass has to be removed and the area graded and compacted..2. 2x4 formwork is erected to contain the concrete until it hardens.  3. Wire mesh is laid inside the forms 4. The concrete is poured and finished and then the forms removed.

120 sq. ft of 4" concrete requires approximately 1 1/2 yards of concrete which will be a minimum load from a redimix plant and cost probably 300 dollars.  Some companies have trucks that can mix onsite but again they have a minimum charge.  To use bagged mix from a Home Depot or Lowes you will need 80 or so bags depending on the size of the bag and rent a mixer to mix it with.  There are wheelbarrow mixers that mix the concrete and allow you to wheel it and dump it.  80 bags of mix at 3.00 a bag is 240 dollars and a mixer is 50 dollars a day.

You might need a pump to get the concrete from the front of the house to the backyard, this will have a minimum charge of usually 150 dollars for one hour of pump time or more depending on your area.

Wire mesh will cost another 50 dollars or as an alternative you can get fibermesh concrete which will not require wire mesh.

To have someone come and form and pour the slab will also be a minimum charge of probably 2-3 dollars a square foot.  Or if they provide the concrete 5-7 dollars a square foot.  I hope this information helps please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com