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Old 06-18-2008, 10:07 PM  
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I agree. It won't be fun, but adding joists from underneath is the only thing that will prevent deflection in this floor.

2x6, 16" o.c.

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Old 12-09-2009, 01:18 AM  
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Hi folks,
Sorry to resurrect this old thread, but I am finally going to have a new floor put into the bathroom of this house. My contractor says he can put in 2x6 joists every 16" to reinforce the bathroom floor, and is installing marble. Again the floor is framed with 4x8s on 48" centers with 1.125" plywood. Will this be strong enough for marble over concrete backerboard once the additional 2x6's are installed?

Thanks for any clues!

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Old 12-10-2009, 11:21 PM  
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Be safe, Gary And get a 6mil. vapor barrier on that, dirt? And insulate the floor or the concrete walls if closed crawl:

Last edited by GBR; 12-10-2009 at 11:27 PM.
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Old 05-03-2010, 08:53 PM  
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Default Similar issue

I have the same subfloor as the person above except that I have 2x4 or 2x6 tongue and groove. I need to go down and measure it again. Anyway, I want to install a 90 gallon aquarium. The spot for the aqaurium actually falls in between the two floor joists. Should I install another floor joist? If so, do I have to pour concrete columns; how deep do you dig or can I buy post jacks from home depot?
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Old 05-05-2010, 11:52 AM  
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Default need to reinforce for aquarium

I have the same subfloor. I need to reinforce for a 90 gallon aquarium; which is about 1,000 lbs. What is the best way to reinforce this. I've had a couple guys take a look at it and they suggested reinforcing the footprint of the aqurium underneath with 4x6 beams and pillars. Do I need to tie this into the existing beams or do I just reinforce the aquarium footprint underneath which is 4'x1.5'. Could somebody point me to a good book or some detailed instructions for how to accomplish this?
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Old 10-23-2010, 01:36 PM  
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Default Reinforcing Floor Deflection

I too have the same type floor and have been under it many times to put in 2x6 joists between the 4 foot beams. I also added some 2x6 blocking in between the added 2x6 for additional support. I used joist hangers and no compressor. I have only 18-24 inches under most of my subfloor and I am almost 60 and it is a pain. If you really don't want to get under your house and you don't have a finished floor yet, you can cut your existing subfloor from the top where it is nailed to your existing beams. With the subfloor removed and the crawspace open, you can easily add your new 2x6 joists from above and then replace your subfloor.

Hope this helps.
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Old 11-07-2010, 11:41 PM  
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crawl under there and add one 2x6 between the joists with hangers. go upstairs and jump on it. then you will feel the difference. From top down would be a waist of time and money.

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