priming cedar siding - also painting - OIL or LATEX?

Hi,

My "new" house (circa 1928) has cedar shingle siding. The paint is peeling badly and I'm working on scraping down to bare wood. Most of the paint is coming off easily.

I want to clean, prime and paint the best way, so it's not in need of a repaint in just a few years.

I've read on Sherwin Williams and also Benjamin Moore's websites that they recommend oil based primers for cedar. It seems they recommend this (my interpretation) because of the risk of bleed through from the oils in cedar knots.

My home's shingles do not seem to be knotty, nor does the existing paint have any issues with bleed through.

However, it does have serious issues with adhesion.

Can I prime with a Latex primer or must I use an oil based one? I'd prefer to use a top quality latex primer rather than oil, because of the ease of cleanup and because I can spray it instead of having to brush it on. I'm sure I can't go wrong with an oil based, yet (as I said) would prefer latex.

Conversely, I don't want to screw this up. Any advice would be helpful.

Right now, I'm planning on using SW's best latex primer and probably their super paint as the top coat. I'd use the duration if it seemed that it'd do better.

Also, any recommendations as to prep (other than scraping/sanding) would be helpful - wondering how to properly clean it (what chemical) and how long I should let it dry before painting

 

Bleach/water solution [for mildew] and TSP [heavy duty detergent] are good for cleaning. I normally spray the cleaner on with a pump up garden spray and rinse it off with a pressure washer. A garden hose can be substituted for a PWer - just takes a little longer. It needs to dry before painting/priming. Time depends on conditions, full sun/wind will dry quicker than shade. Expect to do a little more scraping after cleaning - the water will lift any edges of paint not bonded well to the wood.

Tannin bleed is the main reason for using an oil base primer over cedar. It may or may not be an issue with siding that old. A big issue with older homes is the lack of vapor barrier. This also causes moisture to pass thru the walls [from the interior] and can cause the paint to lift Because of this fact, these types of homes do better with a latex primer and latex finish. But, tannin bleed might be an issue and it's not corrected much by latex primer.

I've used SWP's A-100 latex primer and IMO you'd have a hard time finding a better exterior latex wood primer. I'm also fond of their super paint. Haven't used much of the duration as it didn't come out until just before I retired.

Either latex or oil can be sprayed with an airless but atleast 1 coat [finish or primer] needs to be brushed or back brushed after spraying. This helps to work the coating into the substrate.

 

Thank you Marksr - this is exactly the clear reply I was hoping for. The home does not have a vapor barrier (of course) but it does have blown-in insulation in the walls. The home inspector promised me that the blown-in insulation had a binder which created a vapor barrier - but I doubt the reality of this. I do understand what you mean about vapor moving through the wall and understand how it can lift paint off.

I do not think tannin is an issue in my case - the cedar is old and seems to be knot free + I haven't seen any tannin issues on the home.

I'll go ahead and wash/scrape/wash/scrape then prime with SW latex + super paint.

Thanks much!

 

You might also want to consider adding flood's emulsa bond to the latex primer. It's some good stuff It will help the latex primer bind to any chalky surfaces [if you have any] I think the oiliness of it also helps the primer to adhere better to raw wood. It does make the brush a little harder to clean up. I usually rinse with water until it's almost clean, a quick rinse with paint thinner [gas would also work] and then a final rinse with water. A good detergent might take the place of having to use paint thinner.