Wire to Subpanel - through basement

I'm installing a subpanel in an outbuilding behind our house. I will be
running 100 amps to it, off of our main panel in the house (200 A service coming into the house). I'm aware of keeping the neutral and ground separate on the subpanel side.

My question is:
From the main panel in our house, I will need to run the wire approx. 30 feet
in the basement, then it will go approx. another 30 feet underground (PVC
conduit) to the outbuilding. I am using Alum. SER. Can I just staple (well actually use pvc or metal C clasps) the SER to the underside of my basement floor joists (I have an unfinshed basement). Or, should I drill through each floor joist (middle of joist of course to not weaken it) and run the SER that way. It's Alum, so it bends easily. Or (sigh) do I need to PVC (or metal) conduit it to the underside of the floor joists. By the way, I upsized the SER (voltage drop tables said 2/2/2/4 was sufficient for 100 A over that length), but I got 1/1/1/3 instead, in case I need to conduit it to allow for the restriction on heat buildup that conduit theoretically creates).

By the way, I live it Connecticut, so if anyone knows CT code, that would be
good.

Thanks in advance for your reply.

Don't know CT code, but the drilling option is obviously the best. If there a finished ceiling? Will there be? Is it a drop ceiling? You could put a runner on your joists - a strip of plywood wide enough for SEU straps across the joists the entire length of the run - and strap your cable to that.

You want to pull SER underground, through conduit?

Unfinished basement...I would attatch to the underside of the joists...

I don't have a citation handy, but under the NEC, I think the requirement to support wires by drilling through joists or using running boards stops at a certain gauge (I think 8 gauge). So you should be fine with just stapling it.