Hi all,  I’m in the process of creating my workshop.  The building is a 60 x 40 post frame construction.  The laminated posts were sunk directly in the concrete.  I’ve carved out a little over half for my shop, 30×40.  I was ready to install the studs between the trusses, then hang my sheetgoods for the ceiling, then blow-in insulation, add lights, etc.

Then someone asked, “What are your trusses rated for?” so I went down a deep rabbit hole of trying to find that information.  I called the company who installed the buliding (it was 20 years ago), they said they no longer have those records.  I callled the building commission, there were no permits with that information, I cold-called some civil engineers and one guy was kind enough to take the basic specs and look at some drawings they had on hand from their retired “truss guy” and said, “you’re probably somewhere around 5 psf deadload on the bottom chord, 0 psf live load”. 

This is too close for comfort.  As stated, the trusses have a 40′ span, 8′ oc, they are of the ‘double fink’ variety.  The top chord is a 2×8 #1 SYP, bottom chord is a 2×6 #1 SYP with 2×4 (#2) webbing in between. 

It seems there are three options:
1. hang standing seam metal panels and add insulation, being careful to not exceed the load. 
2. One of the local engineers said, off the record, “you could sister the bottom chord to give it more strength” but that he wasn’t giving official advice just that he’d probably go that route. 
3. Add some type of support, like a post & beam which runs perpendicular to the trusses but I’d then have to cut footers in to absorb the load. 

This shop will have a lot of difficult to replace woodworking machines and tools.  I say all of this to be clear that I’m going to great lengths to turn this into a nice shop space and I don’t want to be close to the rating of the trusses.  There will be lights hung, ductwork for dust collection but that’s mainly it. 

Are there any suggestions on how to proceed?