Repainting a porch rail, top surface only (vacuum, installed, stain)

[pikabike]

The contractor painted it during the wet season (late 2012) and paint at the knots cracked and sloughed off, followed by the rest of the surface wearing through awfully fast. They had to redo it once right away. The second time lasted longer but is now toast again.

I suspect the wood was not completely dry and they began painting anyway.

I intend to fix it myself. Would the following steps be adequate to result in a more durable finish?

1. Clean the top rail on its top and sides.
2. Lightly sand the top surface, then vacuum away the sanding dust.
3. Mask off everything but the top surface, using low-adhesion painter's tape.
4. Prime top surface with an oil-based primer, and let fully dry. (This might be the hardest part, since the weather is swinging between damp and overcast, and sunny/hot/maybe windy.)
5. Paint top surface with two coats of 100% acrylic latex paint.

Should I reverse steps 2 and 3? And would a foam brush or bristle brush be better for wood?

I have painted interior walls but nothing that had to dry outdoors or be protected from too much sun. The porch gets intense sun due to southern exposure.

I am glad the house itself was painted in a long dry period. The GC told me it was the first house he had done in thirty years of building that did NOT get rained on during the painting. Unfortunately, the rails were installed and painted months later, when the weather switch had flipped.

[cdelena]

I have found paint on flat outdoor surfaces never lasts so I stain my handrails and deck surface.

[K'ledgeBldr]

The question is- what kind of wood is it?


That can make all the difference in the world as to primer; and maybe even the paint.

[pikabike]

I don't know what kind of wood it is. Does not look like cedar, redwood, or pine.

[K'ledgeBldr]

Originally Posted by pikabike

I don't know what kind of wood it is. Does not look like cedar, redwood, or pine.

Just speculation on my part...

But, if I had to guess its probably PT. Hence the reason for the paint failure. There are specific primers that are formulated for PT. Even though flat exterior surfaces do take quite a bit of abuse (as previously stated), that doesn't mean you can't get 5-6yrs of service out of a surface that has a proper primer/sealer and a good durable paint.

Although I get you're trying to preserve what you have, you may want to consider a different top rail. There is PT cap that is cut with a double bevel so it sheds water. And there are several "alternative" materials also.

[pikabike]

I was looking at another piece at the bottom of the porch rails that was left unpainted. I think it is pressure-treated wood (is that what you mean?). If so, probably the painted rails are the same material.

Thank you for the info on special primer. I will look into capping that rail as an option.

[ormari]

Originally Posted by pikabike

I was looking at another piece at the bottom of the porch rails that was left unpainted. I think it is pressure-treated wood (is that what you mean?). If so, probably the painted rails are the same material.

Thank you for the info on special primer. I will look into capping that rail as an option.

Hey pikabike. So it was constructed in 2012? If you do have unpainted rails, you may be able to spot some markings somewhere on it, giving you a clue about the material. Could you ask the contractor?

There are different types of pressure treated wood (PT). Where I am, it is mostly Southern Yellow Pine treated with a preservative called ACQ. An older preservative was CCA, but that has pretty much been deprecated due to the arsenic content and isn't used in residential construction anymore. I don't know for sure, but for proper paint adhesion, choice of materials/techniques might depend on what the preservative is. My reasoning is that proper fasteners for PT depend on what preservative was used, so paint may well too. You might investigate that. Since your porch was built with PT within the last decade, it is probably treated with ACQ, but there are other preservatives used.

PT is almost always dripping wet when you get it from the lumberyard/home center. After construction, it is best to let it acclimate before painting if it is used "fresh from the yard".

If I were building a porch out of wood, I would use cedar, mahogany, or possibly pressure treated wood. I also would use a judicious eye when selecting wood, aiming for wood without knots or with very tight knots. But since you have them already, you might treat them with a shellac based primer such as the one from zinnser. But for the best advice, go to your local paint store (not a big box home center, but a store dedicated to paint) and ask them what product they recommend for knots in an outdoor environment.