Should you use a paint and primer in one for interior or exterior painting?  Using this class of paint could cause bonding and adhesions issues in the future so I highly recommend steering away from this option.

A paint and primer in one will lack the proper adhesion qualities needed on most surfaces.  The result could be peeling or flaking paint in the future.  So why do paint companies manufacture such products.  I spoke to a high level Sherwin Williams employee and a paint rep who told me SW was just following Behr who created labels with such wording cause the consumer demanded it.  The SW employee said SW had to stay competitive with Behr so they followed suit. 

Do paint and primer in one coatings perform any better then straight paint coatings.  From my experience I have not seen a difference.  If you are painting bare wood, bare metal, new drywall, glossy surfaces, contaminated surfaces, new block or concrete you will need to prime if you want optimal adhesion and life expectancy of your coating.  Never trust a paint and primer in one to give you the bite or etch to these surfaces. 

I would feel comfortable using a paint in primer in one on a previously coated surface in sound condition but then I would feel comfortable using just a high quality paint.  So do I need to prime a previously coated surface?  That will be another topic for another day.