Construction Industry/load capacity


I just acquired a hot tub. it is 8x8 ft and weight is 765, I think it holds 7 people and 510 gallons of water. I need to put it on a deck rather then a pad. I have someone doing this. It is a 14x14 foot deck and I am concerned how many supports are needed and the size of the joist, etc to make certain this will last and hold up to the weight? I do not think they are making it heavy enough but can not do the figures to know what I will need to do the job. It will also have a roof over it.

Hello Edna,

I don't think you will like this answer.  Your hot tub, water and people have a total weight of 6,500 lbs. (I assumed 1,500 lbs of people.)
That calculates to 101.56 lbs per square foot under the hot tub.  When the tub is empty the weight per sq. ft. is only 12 lbs.  As you can see, water is heavy and your hot tub will hold over 4,250 lbs of water.

I recommend that you isolate the hot tub on its own foundation.  That is, build an 8' x 8' frame with 9 columns going to the frost line. Use 2"x 10" rim perimeter and joists at 12" o.c. with a maximum span of approx. 4'.  Apply the floor decking in long (14') pieces over the entire deck and the hot tub framing is concealed and the weight distributed. You may want to consider plastic decking which looks like wood will not deteriorate.

As a safety factor, you may want to contact your Building Dept. and ask them what their minimum standards are for supporting a hot tub, given all the above weights.

I hope my reply has been helpful.

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Roger Zona


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.


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.

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

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

Michigan State University University of Detroit BS in Engineering

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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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