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Weight bearing capacity of flat roof


BGC's Avatar
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10-19-12, 12:22 PM   #1  
Weight bearing capacity of flat roof

Is it possible to estimate the weight bearing capacity of the following flat (7% slope) roof? The room below is open beam.

2" x 6" T & G Western Red Cedar or Douglas Fir over 4" x 10" x 18' beams at 5' OC. Room size is 18' x 30'

Thanks

 
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10-19-12, 12:33 PM   #2  
So the 4x10" beams are at 5' OC?

What's the spacing of the 2x6s?

 
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10-19-12, 12:58 PM   #3  
The 4 x 10 beams are 5' OC.

The 2 x 6 T&G is flat on top of the 4 x 10 beams There is no spacing between the 2 x 6 material.

 
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10-19-12, 01:00 PM   #4  
Duh, you said T & G....

 
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10-23-12, 12:48 PM   #5  
Play it safe, and pay an engineer (licensed P.E. in your state) to run the calculations for you. You haven't provided enough information to accurately determine capacity, such as what the beams are composed of, or what the roof sealing surface is composed of.

 
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10-24-12, 02:59 PM   #6  
I would hire an engineer if I was adding solar panels or equipment to the roof. I'm tearing off 3 rock roofs and adding 1 new one with 1/4" MLV for sound attenuation. The 3 old roofs probably weigh 10 psf. I'll keep my new assembly to 10 psf or less.

 
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10-24-12, 06:22 PM   #7  
Since the roof you're adding is likely to be less weight than the 3 layers you're removing (presuming the MLV weighs less than 2 layers of rock), exactly why did you ask the question in the first place?

 
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