Prime PT steps in garage?

Old 12-26-10, 04:32 AM
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Prime PT steps in garage?

We want topaint two steps made out of PT wood coming from the garage into the house. Two questions:

Should I prime them before I paint them?
Can I get away with regular semi-gloss wall paint or should I buy floor paint?

Old 12-26-10, 05:28 AM
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I would advise against painting them, IMO you'd be better off applying a deck stain to them. It will wear better and shouldn't be as slippery if your shoes/boots are wet.

If you use paint, you do need to prime and use a floor enamel. Some porch and deck paints specify thinning the paint 10-15% and using that for a primer. It is not a good idea to use wall enamel on the steps.
Old 12-27-10, 05:50 AM
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I'd stain before I'd paint but personally, I wouldn't bother with any coating at all
Old 12-28-10, 09:08 PM
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Here's what the problem is:

Your pressure treated wood, being in your garage, is exposed to the same temperature and humidity of air as it would be if it were outdoors.

Wood swells and shrinks with changes in it's moisture content caused by seasonal changes in the temperature and humidity of the air around it. So, to accomodate that expansion and contraction of wood outdoors, paint companies make EXTERIOR oil based paints that dry to a softer and more elastic film than interior oil based paints.

But, elasticity and hardness are mutually exclusive. To stand up well on any hard working surface (like a floor, or a deck, or stairs), the paint has to dry to a HARD film. Otherwise dirt gets embedded in that softer paint underfoot, and your painted stairs won't stay looking good for very long.

As a result, about the only paint suitable to your needs would be an exterior oil based paint, but it's not going to stand up to foot traffic nearly as well as a much harder drying paint like a polyurethane floor paint (which is really nothing more than polyurethane hardwood floor finish with pigments inside it to give it colour and opacity).

The best course of action would be to just use a stain on that PT wood or put some other coating on those steps, like a vinyl or rubber stair tread. Since it's a dry area inside your garage, you might just consider carpeting them.

If you do paint, you should prime with an exterior oil based primer first. I'd opt for an exterior oil based paint for a top coat, and put some traction grit in the paint to provide good traction even when the steps are wet. And, pressure treated wood shouldn't be painted for two years after pressure treating. That's cuz pressure treatment is done by injecting water soluble chemicals into the wood under pressure, and it can take up to two years for the water injected into the wood to evaporate out of it.

I wouldn't use ANY latex paint on those steps at all. Latex paints just don't dry to a hard enough film to provide good service on a working surface like a floor, steps, shelves, window sills, mantles, etc. They get scratched up and embedded with dirt and are constantly needing cleaning to look good. You're much better off with either no paint at all, or a paint that's hard enough not to get dirt embedded into it. And, I don't know for certain that even an exterior oil based paint would be hard enough to stand up well on steps.

This is in fact the same problem and solution that most homeowners face when deciding how to finish their decks. Most chose to simply apply a stain and then a water repellant to the deck and leave the wood essentially bare. Those that paint face the same difficulty of finding a paint that provides high hardness while still providing sufficient elasticity.

You COULD glue or screw down a much more dimensionally stable material (like steel plate) onto the wood, and then paint the steel plate with a very hard drying paint, like an epoxy floor paint.

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