How do I say ‘no’ to a pack rat?!

Sorry in advance for my answer to be negative, but here goes. My brother is a pack rat/hoarder of many years. Our family has done the clean out many times. It never lasts. It’s a psychological condition that he can’t overcome, at least not so far in his life, and yes, it’s generally always a touchy subject. Even if you get your father to come into your home with far less he will find a way to clutter it up, he just won’t feel comfortable or strangely, safe, there without all the stuff. It’s a tough condition and I really doubt you’re going to change it at this point in his life

If you move your parents in, you will be overrun by Dad's clutter. As Daughter0f1930 wrote above, he'll require mental help to get beyond it--if he even chooses to do his best. You'd all be better off selling the house and moving your parents into an apartment so they don't have to worry about maintenance. Or better yet, perhaps give your father a choice: either he seeks psychiatric help for his hoarding or he moves into an apartment.

Look into Senior housing. They are subsidized by HUD and charge rent on scale. Parents can get help with utilities and food stamps.

You DON'T say "no" to a pack rat. You're under an illusion that he wants to change and get rid of what he has.

Your father is mentally ill with the disorder of hoarding. It can be treated but the person has to want treatment. If your dad won't even talk about the subject without getting irritated ("touchy"), I doubt that he will be interested in treatment/changing.

Unless you won't mind constantly fighting with your dad about his problem AND finding junk around your new home, I'd suggest that you abort this idea of moving them in with you.

I would NOT buy the big home, I'd take what they can get from the sale of their home and get them into a nice senior apartment. The money they get from the house can supplement their meager income. They might even qualify for Section 8 or low income assistance.
I would refuse to haul all the junk with them to the new apartment. If he wants to pay for it being moved, he can.

Research hoarding disorder. As a minimalist, you will loose your mind within a month living with him. He's not going to change.

I think that you mention someplace that you have worked in a Memory Care Unit. Are you still working as a nurse in a Memory Care Unit or Long Term Care facility? If so, do you realize that after working 8, 10, 12 hours with the elderly, you will be coming home to "work with the elderly"? You will have NO REST! Your "name" is "tirednurse02"---so if you are "tired" now, how much more tired are you going to be trying to take care of your parents AND working as a nurse?

Who has your parents Durable POA? Moving your parents in with you is NOT the only option! The other people have given you some good options.

You stated "I’m almost a minimalist! Clutter freaks me out!" Have you watched the TV show "Hoarders"? That is how YOUR HOUSE is going to look in a couple of years. You will NOT be able to control the clutter that your Dad brings into the house. He has a mental disease and needs professional help.

You really need to STOP BEING A NURSE and BE A DAUGHTER! I have been told that many times and I wish that I had listened to them. I think that my Mom and I would have still lived together, but I think that there are some things that I would have done differently. Since 2017, my Mom has been in a nursing home and I am still living in the house we shared. My health has been compromised and I can't do a lot of the activities that I used to do even one year ago. Please listen to our advice and reconsider living with your parents. I am afraid that you are going to live to regret it.

There’s no reasoning with pack rats/hoarders/junk fiends. Whatever you care to call them, they’re all the same.

100% defensive and belligerent, if any discussion is attempted.

Oh, and two things make this trait worse: #1) Age #2) Dementia

Forget the “come to Jesus” convo. Forget making an offer of “you can bring only XXX much of your stash.”

As some others above have suggested, please consider looking into low-income senior housing (or such) for your folks.

You went to college so you could support yourself. Not your family.

Don’t let your parents guilt you. They’ve had decades to figure out how to be a tad more resourceful. And don’t let your siblings hide behind “She’s single and she’s the nurse in the family.”

Your health and sanity matter, too. Don’t “good girl” yourself into early disability or an early grave. (It happens.)

My Dad is a pack rat/hoarder. When my step mum was around she was able to rein him in, but for reasons beyond their control they no longer live together.

Your father will not change, just as mine will not.

Mine also cannot pass up a good deal, even if he has multiples of the item. He also hoards food such as canned goods and bags of powdered milk. He is 89, we could stock his tomb for eternity.

My dad was a hoarder. He went "dumpster diving" (literally crawling around inside dumpsters) into his mid 70's. His drawers, cupboards and closets were filled with old styrofoam containers (from Meals on Wheels) and I threw out 60 frozen Meals on Wheels dinners in the freezer and 15+ in the fridge after he died! They were SUPPOSED to be eaten. Better to save them.

He'd pick up junk on the street or sidewalk. Anything thrown out by other tenants, he grabbed and brought home.
(Me) "Why do you want that old broken coffee pot?"
(Dad, "Oh, I'm going to FIX it". It the wound up in the "broken electronic graveyard" in the corner of the living room. Always a project for another day.

Is your father mobile? Can he still drive?
If so, I'll guarantee that "good" items will cross your threshold. They probably will be stored where you wouldn't look.....until all that space gets full. Bugs may also be coming in on the things he brings in. How horrible for your new house.

I'm sure there is research out there with the statistics on how often horders, who have completed treatment, have relapsed. It's an addiction, like being addicted to anything else.

Please reconsider. Have a heart to heart talk with your dad. You'll see he won't give up any of these "treasures". That may change your mind.

The "Hoarders" show is definitely realistic and hard to watch. An episode may conclude with "new beginnings" and a clean place to live, The question always remains how long it will last.