do you have any recommendations on using acrylic coating instead of replacing the whole roof?

how long does the coating last?

What is the current issue now ? Rust ? Leaking at the screws ?

Both. Rust and leaking

Is this on your home or a barn? I generally reccomend replacing with standing seam if a house. If you have exposed fasteners on your home, that's generally the best way to go in my opinion. I would not coat it. If I didn't want to tear off then there are options to put standing seam over R panel.

Barn

In that case, check out Karnak. We have a crew that does this and will offer a warranty with it. It's cheaper than reroofing. You can do just seams and fasteners or we'll do the entire surface if the metal is really bad.

There are other similar products. JP may be able to speak on those, but I'm not familiar with all of them.

Is this on the Karnac label?

RIP