Replies

1. 
   Guest_ | Mar 28, 1999 06:42am | #1

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   Bob

   Depending on your definition of a real solid floor, I would suggest using TJI/Pro/550, 16" joists and keep it below 30 foot spans @ 12" centers.

   It would be easier of course to split the basement span in half, 21 ft is much easier to work with. You could drop to a 12" joist.

1. 
   Guest_ | Mar 28, 1999 05:02pm | #2

   *Bob and Gabe - I would syggest a 24" deep floor truss spanning no more than 30' clear. Any longer than that, and you might have problems with vibration. There is no floor system I know of that can span 42'. A 16" I-joist shouldn't span more than about 24', no matter what centers you put them on. Reducing spacing does not make a floor system stiffer. I would also state that I think a 12" deep floor system should span no more than about 18' regardless of what the san tables may say. Remember that span tables are an indication of strength, not stiffness. They are not directly related to each other.

1. 
   Guest_ | Mar 28, 1999 05:20pm | #3

   *Morning RonI tend to lean towards the conservative side on all calculations myself.I only was giving TJI information as an alternative and I use my truss joist software only to check out possibilities.If Bob would have gone to a qualified dealer or distributor, he would have been made aware of the limitations to the application.But as far as what I would consider a solid floor, you're absolutely right that for a span of that size, I would never pass the 24' mark either.

1. 
   Guest_ | Mar 30, 1999 04:50pm | #4

   *Bob - ther's a good article on floor vibration at:http://www.inspectamerica.com/html/bouncing_floors.htmlI recommend reading it before you choose a floor system.

1. 
   Guest_ | Mar 30, 1999 05:05pm | #5

   *Splitting down the middle + or - 3 feet would be my choice. Spaning the center beam instead of lapping or butting will give a stiffer floor. If you go with truss joists go with wider flange at 16" o.c. instead of narrower at 12" o.c., it will cost less and utilities will be easier to run. Follow the tables and glue the sheathing. If you must use bridging, the only thing that I have had no troubles with was blocking with stubs of truss joists glued and screwed between the joists. Usually I don't use any blocking or bracing up to 25'. In the basement if it isn't rocked, I will strap with one 1x3 or 1x4.

2. 
   Bob_Ballenger | Mar 30, 1999 05:06pm | #6

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   I'm Building a new house and would like to know how far I could span and still have a solid,Quiet floor with open truss floor joist. My house is 42'X 65'. I would appricate any knowledge.
   Thanks
   Bob Ballenger