John Sayers' Recording Studio Design Forum

Hey guys,

I'm building in an attic truss system and requested an engineered letter that documents the load capacities of my sturcture. I received this today and want to have the experienced builders comment on my weight limits.




(I'm not sure if these images will be legible. If not I'll host the pdf elsewhere.)

I think the bottom line is 58psf live load. Can you confirm this?

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7 times down, 8 times up

why?

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inkspotproductions
www.bantamstudio.info

b/c I plan to install 5000 lbs of material and equipment and can't afford for the structre to collapse during an ice storm or hurricane.

not to mention attic trusses aren't built to carry excessive load like floor joists.

why not? Are you fimilar with Loading calculations?

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I have no idea about load ratings other than lighting bars and tri-truss.
I just thought it would be nice to know why and what you were doing, thats all

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inkspotproductions
www.bantamstudio.info

A definition of what is a dead load might read that it is any part of the building that would have to be cut from the structure e.g. sheetrock, floor plywood, floor coverings, etc.

The live load is whatever an occupant may place into the structure, couches, beds, chairs, etc.
A typical living area in a residence may have a 40psf liveload. People and furnishings and all the unexpected items that may come along.

A 10psf deadload is where you get the numbers to interpret how much you can load this area. This [10 PSF deadload] is a typical number often seen for standard residence. It includes, but is not limited to, sheetrock, insulation, electrical, etc. This is the number that needs to be high in order to submit the structure to additional loading above and beyond what is considered typical as it applies to a dwelling.

Even then, the 58psf liveload only applies "if" you are within the boundaries established by the vertical members at location 13 and 15 (according to your drawing). Again, this is a live load calculation. The drawing assumes that the builder has installed the correct blocking and wind sheathing and all purlin as described in the bracing table.

Hope this helps,

Brien

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Brien Holcombe
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Sound: You can't stop it, you can only try to contain it.

I thought Live Load was Dead Load plus "whatever an occupant may place into the structure, couches, beds, chairs, etc." plus typical enviromental stress such as snow weight or wind forces.

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7 times down, 8 times up

Live load is what an occupant may bring plus environmental impacting as snow, wind, etc. PSF that can and does change.

Dead load is whatever is a permanent part of the structure. Including the structure

Live load plus dead load equals design specified load in relation to a truss.

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Brien Holcombe
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Sound: You can't stop it, you can only try to contain it.