Construction Industry/floor joist dead load

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Expert: - 8/18/2009


Question
Two Questions, I am trying to do my own remodel drawings before sending them into my local building department. I have the latest IBC book and am using that for reference. I have 2x10 floor joist that are 16" oc and 19'6" long constructed our of Douglas fir.  Right now I am not meeting the live/dead loads that are being tabled. I need 30/10/5 (bedrooms above) can I get that by adding extra joist so that my spacing is 8" oc.
At the end of my floor joists I want to replace the shotty post and beam system that is there.  How can I figure out what size beam I would need to carry the floor joists (2nd floor) with a 18' span.

Answer
Eric,

I understand your wanting to produce the drawings for your project.  However, you are dealing with explicit code conditions.  Since the 2x10's don't meet your requirements, you should test the use of larger members or the spacing of the joists.  As for the supporting beam, the same test applies only the beam can be a solid timber or 2, 3 or 4 dimensional lumber pieces that are bolted together to meet code.  I suggest you either meet with your local building official and review the code requirements or hire a structural engineer to determine the proper size joists and beams.  

My first impression is that the 2x10's are not adequately sized for the span.  Usually a 16 foot span is the limit.  At nearly 20 feet I suggest a 2x12 @ 12" o.c.   That may be adequate.  The IBC will give you the limits.

I hope this has been helpful.

Roger
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Roger Zona

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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.

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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.

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

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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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