Expert: Bruce E. Johnson - 1/12/2010

Question
QUESTION: Hi.

First of all, I would like to thank you advance for your time and expertise.

I am wondering how the second story of a 2009 constructed home in the Los Angeles area might handle the following load:

A semi-permanent 4 foot by 4 foot vocal recording booth weighing about 1300 lbs. placed near the corner of the room, which measures about 12 feet wide by 12 feet deep, plus about 700 lbs of other miscellaneous recording equipment and furniture, dispersed along the walls of the room, plus myself in a chair (total about 200lbs).

I know you may not be in the area, and I do not have access to the building plans or the builder, but I am wondering if this sounds like a set-up that could be detrimental to any 2 story homes I am considering purchasing for my first home.  Could you please give me a basic sense of whether or not this should work.

Anything you can recommend?

Thank you so much!



ANSWER: Hi shaun, you are only talking about 80 something pounds a square foot on the sound equipment, which, along an outside wall where the floor joists are strongest, shouldn't pose a problem.  If you take the entire live load of the room  1300+700+200=2200 lbs. and divide that weight by 144 square feet you are only talking 16 lbs. per sq. foot which falls into the parameters of most floor system designs.  It is always a good idea to keep your concentrated loads closer to bearing walls instead of in the middle of the joist span but other than that I don't see a problem unless your home has undersized joists for the spans involved.  However, as new as the house is, and the city location, your home was inspected and the plans approved by an engineer.  I hope this information helps, please feel free to write again regarding this or other matters, sincerely, bruce e johnson..bejohnsonconsulting.com

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

QUESTION: Thanks for the prompt and clear response, Bruce.  Forgive my ignorance, but when you say to [keep concentrated loads closer to bearing walls]--would keeping the 1300 pound vocal booth in the corner of the room meet this parameter?  Or is there other information I would need to seek out, in order to know where the joist spans are weakest (I assume this essentially would be the middle of the center of the room).

Thank you again!


Answer
Hi again shaun, the closer you get to a bearing wall the stronger the joists become.  Think of a plank laying over two sawhorses.  If you stand in the middle of it, it will sag, if you stand next to or over the sawhorse it won't.  Same with your joists, the closer you get to mid span, the more flexible they are. If you have concerns about the concentrated load for the vocal booth it may be possible to attach it to the wall studs also which will help keep the weight being transfered to the floor system to a minimum.  I hope this information helps, please feel free to write again regarding this or other matters, sincerely, bruce e johnson..bejohnsonconsulting.com