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Re: Weights for design

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David Smith wrote:
I am reviewing the loads for wooden trusses on a church roof.  The architect specified R30 insulation and automatic sprinklers.
It looks like the weights for each of these can vary all over the map.  I would appreciate seeing some typical design weights used by the rest of you.
Dave Smith
For R30, an average value is R=3 per inch.  This comes out to about 10", although batt insulation vendors list 9" thickness for R30.  Using ASCE-7 loads, fibrous insulation is 1.1 psf/inch.  The insulation DL comes to about 11 psf. 

For the spinklers, assume something like 2" STD pipe at 10' spacing. The pipe when filled with water is 5.10 plf or .51 psf.

 The total dead load is 11.5 psf but doesn't include the sprinkler mains.  You would have to adjust the sprinkler DL based on what the mechanical engineers are coming up with..