Jobsaver,
I agree with what the others have mentioned. "Yes, penetrations are allowed!"
They have to be sealed with approved sealants, gaskets, metal collars, other
approved materials. We have used intumescent type caulkings around the
pvc piping.
The stair from the attic area [ over the garage ] can be sealed, but it usually
costs more to achieve it. There are fire rated stair assemblies, but they are
pricey as well. If the contractor doesn't want to install a completely rated
"pull down stair", then a 1/2" [ minimum ] draft stop wall would be required
to separate completely the residential areas from the garage area ( Section
R309.1 in the `06 IRC ).
One problem that we constantly have to deal with is the contractors lobbying
about costs and the "non-sale-ability" of having attic pull down type of stairs
located inside the residence. And when they install them in the garages,
not one of them has ever installed a draft stopping wall to separate the
residence from the garage. That building element is not a desirable feature
to people who want large attic spaces to store more and more stuff!
As the theory goes, ...separation is required to prevent a fire that has
started in the garage / storage room from migrating to the attic areas,
by-passing the smoke alarms and being fully developed before any of the
occupants even know it's there.
Hope this helps!
.