Construction Industry/monolific footers

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Expert: - 1/27/2011


Question
QUESTION: Building a 30' x 40' garage with attic truss across 30' span.
Live in West Virginia, rarly gets below -10 degrees F. Weight will be on the 40ft. lenght walls.
Will a monolific footer-slab be a good choice?
How deep does footer have to be?
         Thanks alot
         Mark

ANSWER: Hello Mark,

If you experience that much cold, your building code most likely requires that the
foundation must be below the frost line.  I imagine that would be about 2 feet.  If
that's the case, you must excavate and form a footing at least 16" wide by 8" to 12"
deep with 2 or 3 steel reinforcing rods.  Then you lay a concrete block stem wall to
grade, pour a 4" thick slab with welded wire reinforcing and then build wood or steel
frame walls.  Don't forget to pitch the slab towards the overhead door(s)so rain water
or melted snow will run off properly.

If you are using concrete blocks for the walls, you can lay the block to the proper
height you need and then pour a floating slab.  Create a joint where the slab meets
the walls using expansion material. Score the slab in the center and both directions
to control cracking.

If your code allows monolithic slab and footing, it must be deep enough to meet the
frost line requirement.  I recommend you check with your building department and talk
to a plan review technician.

I hope this was helpful.

Roger
Ask The Contractor
I'm in Florida where we do pour monolithic slab and footing - but of course, there is
no frost line either.  When I lived in Michigan we had a 3' frost line.  

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

QUESTION: I appreciate the help, need to get below frost line got it.

What about the strength of monolithic compared to block footer?

         Thanks again,
         Mark

Answer
Hey Mark,

The structural limits of either footing depends on the load.  Obviously
a two story home requires a larger footing than a single story home.
The wide continuous footing with steel reinforcing is stronger than a
monolithic slab/footing.  Usually the depth of a monolithic slab is
included in the depth of the footing when calculating loads and limits.

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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