As a firefighter, I've grown to really despise lightweight construction methods. Remember - most of these methods are used to save $$ - and if the book says they can be placed 48"o.c. max, you can bet they will be.
This, of course is very different than the fudge factor allowed by the "old" 2x10 16"o.c. When lightweight fails, it fails BIG.
They're even telling us FF's to not go into lightweight buildings if they've been exposed to fire conditions due to the rapid failure of these things.
I won't cut trusses. We've even been warned about cutting them when venting roofs causing failures.
I hate lightweight.
