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Construction Industry/Fill that is placed below a concrete slab and compacted

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Expert: - 7/24/2008


Question
What kind of fill do I need below a slab? What is it called and where would I buy it? I understand the concept of installing it  in lifts, but I'm not sure how to do an onsite compaction or density test. Is such a test done per lift?

Thank you Roger - Larry

Answer
Larry,

We call it "Structural Fill" - clean with no roots, debris or trash - and usually a combination of light loamy clay with sand.  It should be readily available in the Ocala area.  Unfortunately, costs have risen because of trucking.

Spread the fill in 12" lifts and compact after each lift.  You can use a "sheep's foot" plate compactor or a vibratory compactor or a rolling compactor.  

The tests must be done by a soils laboratory.  Down here it is mandatory that we submit test results showing a 95% compaction after you have filled to your grade.  The cost is not too serious.  Check with your local building dept.  They may not require a certified test.

Compaction is done as a prevention of settlement and cracks and is well worth the cost.  I have had to make repairs to houses that have a settled slab or footing.  Now it becomes costly!

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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