Construction Industry/Concrete Slabs

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Expert: - 5/17/2009


Question
I am currently building a house and the builder has told me that i will need to upgrade my slab.
Just curious as to the differences between a "M" and a "H" class slab

Answer
Hello Mile,

I need a few more facts - but with certain assumptions, there probably is a logical reasons for the upgraded slab.

First are soil conditions.  Most codes require a density test on the soil to receive a slab.  This is most common with a slab on grade (no basement) rather than a basement floor.  If the density test was not up to code, and soil conditions are static, a change in the concrete specifications may be required - higher strength concrete, more concrete reinforcing (wire mesh or rebar) or thicken the slab.
Your local or state codes have assigned a specification designation to concrete slabs, thus the "H" to "M" change.  Can it be assumed there are four more categories (I, J, K & L) of concrete specs?

I suggest you contact your building department and ask a plan reviewer to explain the differences including costs.  The cost of the upgrade should only be the added cost of material(higher strength concrete, more steel, etc.) since the labor will be the same (form, place and finish) unless the added steel is a rebar mat rather than a wire mesh.  Rebar requires more time to put in place.
(The downside is - an experienced builder should have a good idea about typical conditions and may have known that the soil in your area may not meet minimum bearing requirements.)

I hope this has been helpful.

Roger  

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Roger Zona

Expertise

I am experienced in all types of construction: residential, industrial and commercial; single family, multi-family, mid-rise and high rise buildings (16 story office building) as well as remodeling, additions and tenant improvements. I can field most any question that relates to general construction. I have consulted with infrastructure (utility) contractors also and have a good general knowledge of underground utility construction for subdivisions and commercial projects.

Experience

After college, I began my career in the construction industry. I chose to become an apprentice Architect and 4 yrs later I opened my own architectural design firm. Six years later I moved to Florida to buy & develop land and build. I became a State of Florida Certified General Contractor and operated my business for 45 years. I built all types of residential and commercial buildings including warehouses, shopping centers, high rise apartments and office buildings and developed sites for other contractors. I retired and became a consultant to the construction industry. I maintain my license and continuing education requirements, operate a small construction company and write a weekly newspaper column for the Palm Beach Post (a Cox publication) with the byline "Ask The Contractor". I am the "technical editor" for a publisher of books that relate to home maintenance.

Organizations
Previously - NAHA Currently - FLCA (Florida Licensed Contractors Assoc.)

Publications
Palm Beach Post newspaper - weekly Q & A column Happy Herald monthly real estate publication - monthly column

Education/Credentials
Michigan State University University of Detroit BS in Engineering

Past/Present Clients
I built a home in Palm Beach for a member of the Pulitzer Family. I was responsible for the completion of a twin hi-rise condominium project for G.E. Credit. I was a partner in the successful development of a P.U.D. (Planned Urban Development) subdivision. I represented the largest home builder from France (Bati Service, S.A.) in the development of a subdivision and the design and construction of the homes.

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