In a previous post says...
This is the main reason I would NEVER build a house with trusses.


There is such a thing as an "attic truss". But, it must be specified at
the time of design and manufacture. Typically, the truss is designed
with an aisle way down the middle and the bottom chord is designed to
carny the weight of stuff stored in a typical attic.

The engineer or architect can specify a heavier than normal load on the
bottom chord. Obviously, the truss manufacturer will do what's typical
unless told to do otherwise. the spec building could specify an attic
truss, but that costs more. Most spec builders on not going to spend
the a few hundred extra dollars if they don't have to.

--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA