How should I clean and repaint a painted wooden deck?

Question

My deck appears to have been painted with just a single layer of paint, which is now peeling off. I like the look of the paint (when it's in better condition, of course), and am uninterested in staining, especially because I'll be adding some new balusters which may not necessarily match the existing wood. I'd like to clean, prime, and repaint the entire deck, and have a few questions:

• Do I need to actually strip the existing paint? Or can I just follow this cleaning method (power wash, scrub with bleach/water/TSP)?
• Because I don't particularly care about the discoloration of the underlying wood, is the above-mentioned chemical cleaning necessary? Or can I just pressure wash, wait to dry, then start priming?
• Should I prime/paint/stain the underside of the deck? While I want paint on the top, I'd be okay with staining the underside, if necessary.
• What kind of primer/paint should I use? This deck is in Illinois and experiences hot summers, cold winters, and plenty of moisture.

Answer 1

Painting a pressure treated wood deck is always tricky. Pressure treated wood does not seem to hold paint well, even with a good primer. Stain is usually a better alternative, but since your deck already has paint, it would have to be stripped completely before using stain.

In order for the paint to stick fairly well, the surface needs to be as clean and dry as possible. Looking at your pictures, I see a fair amount of algae in the grain of the wood. This is a very normal condition. You should however, use the pressure washer and bleach/water/TSP shrub down method to clean it up. I'd wait until April or May when temps are up in the 60's to 70's to help dry the deck and open the grain.

Select a high grip primer rather than a stain blocking type. Many manufactures have come out with new formulas that are designed to bond better. When you apply the primer, don't rush. Simply rolling on primer too quickly is not good. The primer needs to be brushed into the grain as deeply as possible. Let it dry completely. Now you can apply your deck paint as normal.

Answer 2

I fought with degradation of stain every year. When I painted the entire board, sealed it, I gained an extra year before the moisture compromised it.

Answer 3

One should first remove as much of the old sealer / coating as possible. This can be done using a pressure cleaner to remove loose flaking paint / sealer. Sanding is a time consuming job and therefore expensive. Often the new sealer you will want to apply is translucent and you will see any peeling through the new coating. So a compromise needs to be made regarding sanding it all of (very expensive) or just lightly sanding and removing flaking paint. If the deck has been taken back to raw wood now is the time to rather oil the deck. Oil cannot peel and flake as it soaks into the wood and does not coat it like most other sealers or coatings. This make future maintenance easy and therefore less expensive.