Yes-

1) Scraping!!! The loose stuff HAS to go.

2) Sanding- A MUST. This goes fast with a Palm-Sander. Remove ALL dust.

NO- NOT Shellac Primer!! Says so right on the can!

Reason: Zinsser's BIN Shellac-based Primer is a very good INTERIOR Primer. It's TOO STIFF of a coating to last long OUTSIDE. SPOT-priming is allowed outside tho', like over knots or bleeding areas.

* TWO COATS of the Peel-Stop. That's literally what I did on my 1996 Steel-sided house last Fall.

* It's kind of thin, & dries to a hazy-clear/white.

* Then, a full coat of Insl-X's STIX Urethane-based Primer. $60+/Gal, but this is DAMN good Primer!!

* Do you HAVE to be this fussy?! No....but.....it'll be VERY durable.

* Lastly, TWO coats of BM Ext AURA.

* DON'T use Flat for Trim areas like that. Use the Ext Low-Lustre or Soft-Gloss.

I'm in SNOWY Fargo, ND. Where I work (NOT a big-box!), I can't afford to give so-so advice!

Faron

Faron, would you recommend Peel stop triple thick or Peel stop clear binding sealer?

I use lots of Peel Stop, some of the regular, far more of the Triple Thick. I sometimes mix them to get the consistency needed.

I do not use them as bare wood primers, although I will use them over a primed surface before applying the top coat.

For your project, I'd go down to bare wood, ideally down to fresh wood removing all the old paint and gray weathered wood.

On some projects, I find it's best to replace rather than prep the existing. I find the man made products take paint better and usually last longer than real wood. Sometimes I will remove and replace, sometimes I'll just cover with a thin piece.

Prime the bare wood with a quality primer. Caulk, if used, sticks best to paint (Peel Stop or a topcoat), and you should do 2 coats of your chosen topcoat.

Paint has always been self priming over a previously painted surface in good condition, so don't fall for the paint and primer in one marketing.

PPF's note of mixing the 2 is a good idea.

I'm torn here tho'.....

The "BEST" answer is get rid of the paint that's halfway off anyway. You then do the PS Triple-thick Primer.

A Paint-Job is really only as good as the lowest layer.....

Faron

Before doing sanding and scraping, you should consider testing that peeling paint for lead so you'll know if you need to take any special precautions.