Another Live Load Question

[JoeBaseplate]

Project: Church bldg with wood roof trusses. See attached. The contractor has somehow talked the owner into having the box shaped attic in some of the trusses to store “light” items like xmass decos etc. For starters the truss manufacturer is not showing any design LL for the bot chord, so that’s not right.

I want to determine the live load criteria for this. Its not a storage, or a catwalk. The closest reference I could find was uninhabitable attics with storage @ 20 psf, but that’s under Residential (well it is house of God).

Would a higher criteria like 40 psf for catwalks apply? I am not sure how to define the load on this area per code.

 

[BAretired]

It is not a good idea to designate an attic space as storage space. Christmas decorations may not be heavy, but they are likely to be combustible. I would try to talk the owner out of that idea.

BA

 

[Lutfi]

If it is to be used for storage, it must be designed for storage. Code lists a light and heavy storage. You cannot massage the numbers to make them work! I am concerned that these things take place especially in a place of worship where large number of people will assemble.

I also agree with BAretired, storage will not get approval from Fire Marshall.

Having said all of that, many of the projects I worked on required bottom chords to be designed for nominal live load. Make no mistake, this load is nominal and is not intended to be used for storage.


Regards,
Lutfi

 

[paddingtongreen]

If you provide an area for storage, people will find things to store in it, sometimes heavy things. Either nix the idea or design it properly.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[RHTPE]

Code issues aside, paddingtongreen is correct. You would be amazed at what will accumulate in a storage space like this. I once had to check a mezzanine in a warehouse that was to be used to store light stuff - like paper. It turned out that the sensible design load for the mezzanine was 250 PSF based on the file storage boxes that had to be stored there. The avaerage high of the accumulated boxes was 5' or so.

Ralph
Structures Consulting
Northeast USA