Exterior House Painting: Do You Need a Primer?

If the paint is in good shape, no, you shouldn't put a primer on it. Primer is used to bond to the bare wood better and seal any sap in. If you need to scrape paint, use a primer on the bare spots.

Agree. Also, just read the directions on the particular paint product you plan on using which will tell you what you need to do.

i generally only use primer on spots that are bare wood.

If you have done any sanding, patching etc. you are better off priming the surface first. The primers job is to give the paint a proper surface to adhere to.

A friend of mine has been in the painting trade for many years. He avoids priming on a job unless the customer asks for it but he always primes first when he's painting his own house. Draw your own conclusions.

LdB

Behr and other brands have all in one primer and finish coat. You'll pay more per gallon, but the convenience might be worth it.

In addition to cracks and chips, look for chalkiness / oxidation. Rub your finger across the paint, if dust comes off the same color as the paint (disregard normal dirt / pollution), the paint is not a fit surface for new paint. You'll need to power wash or scrub brush the surface before painting. If wood is involved, allow many days for the wood to dry because a power wash injects water deeply into the wood.

There is no substitute for putting on two coats of paint, one primer, and one paint.

Jon

You're mistaken. There is in fact a substitute for separate coats of primer and finish, it is the product that I mentioned.

I have used the Behr product. I had 20 feet of soffit to replace. I used one heavy coat on bare plywood. It looked fair, about what you might expect with two coats. It is now weathered for almost 3 1/2 years, and there is no peeling.

The basic question is why you are putting white latex house paint over white latex house paint. If the original paint is in perfect condition, then why do the job? If it's not in perfect condition then you need to prep the surface. Most likely this will involve treatment that will require priming of at least some areas.

RTFC! Go to the store, look, read, ask, decide or go to another store and repeat.