When I was a kid, there was this new-construction, two-story house down the street from us. It was your typical Florida build – slab on grade, concrete block, etc… The second story was stick-framed, of course. It was fascinating watching the process, but then… one day… nothing. Construction stopped.
Days turned to weeks, weeks turned to months, and after about a year, I asked my parents: Why didn’t those people finish building their house? They swiftly and simultaneously responded, “because they ran out of financing.” I paused for a second, then said, “oh…” I got it. They didn’t have enough money to finish building it.
Another year or two went by before someone else came along and finished the house. I’m sure they probably had to replace a lot of that framing lumber on the second story. If they didn’t, I feel bad for whomever bought that house. There’s no way it was still in good shape after years of exposure to the Florida humidity, rain, and heat.
A few years later, the same thing happened again in another neighborhood. This time it was the house next door to us. The situation was much, much worse, though. This was a massive house. Basically a mansion. I can’t remember if it was three stories or just two, but it had a lot of wood construction.
Everything above the first floor was wood. Wooden stairs, wooden balconies, plywood sheathing… all bare. It sat unfinished for about three to five years. I remember seeing the plywood turn green from all the algae that grew on it. The family that eventually finished it must’ve spent a fortune removing and replacing all that damaged lumber.
Seeing this happen, not just once, but twice in a relatively short timeframe has served as a reminder to me: You never know what might happen that could bring your construction to a halt. As an owner-builder who works alone, I have to be especially cautious. If something happens to me, no one else is going to finish my buildings for me.
I could get sick, have a financial emergency, befall an accident…. There are a lot of bad, unpredictable things that could happen, leaving my lumber exposed to the elements for an indefinite amount of time. That is why I paint my lumber – it protects wood.
Think about it: apart from aesthetics, the other reason we paint wood siding is to protect it, and it works. If it didn’t, we wouldn’t waste our time and money on paint. So why not just paint all the wood?
The Benefits of Painting Lumber
So, paint protects wood, but let’s talk about how it protects wood, as well as some of the other benefits. However, before I go any further, let me just say, I realize most builders, especially production builders, are never going to do this. They don’t want to waste time painting lumber on a job site.
They’re also working so fast it doesn’t matter as much. A good construction crew can frame, sheath, and wrap a house in as little as a week. Once the house is wrapped, the envelope is sealed, so it doesn’t matter if it gets rained on or snowed on.
In my case, however, as an owner-builder working on my own schedule, I can spend as much time as I want on any detail. I’d rather spend a few days painting all of my lumber than deal with potential problems in the future.
Most importantly, paint protects lumber from bulk water. In other words, large amounts of liquid water saturating the wood. Why is bulk water such a problem? Because if fresh lumber gets soaked, especially many times over, there’s a good chance the wood will warp.
Sure, I can cover my boards with a tarp while they’re sitting on a pallet, but what about after walls start going up? It would be extremely tedious and annoying to tarp and and un-tarp my entire building every time I work on it. To me, that would be more of a hassle than painting every board.
A single coat of semi-gloss paint – more on that later – can shed a lot of water off wood; especially wood that is standing vertically. Most of the water beads up and runs off the surface instead of saturating the wood.
Termites don’t like to eat painted wood. I’m not saying they won’t, but they would much prefer a piece of dead, decaying wood on the ground rather than freshly cut, freshly painted lumber up on a foundation. I’m also not saying this is the main, or sole, way I plan on preventing termites. I just figure I might as well do everything and anything that can reduce the risk.
Latex paint is a mild vapor retarder. It falls somewhere just outside of Class III range – between 10 and 20 perms. That means it slows the diffusion of moisture but by no means blocks, so the wood can still dry out easily.
If you live in a humid climate, this one might be of extra importance for the comfort and lifespan of your home. The paint, at least in theory, should reduce or slow hygric buffering – the wood’s naturally ability to absorb lots of moisture from the air, which in turn will be redistributed in to the building, increasing the humidity.
Weather Resistive Barrier
I only put a single coat on my studs because studs are quite resilient, and multiple coats would be rather excessive – painting studs at all is already a bit excessive. However, I put at least two thick coats on my plywood sheathing. Plywood is much more sensitive than solid boards.
It is my opinion that if you thoroughly paint plywood sheathing and seal your seams, you eliminate the need for a weather resistive barrier (WRB). In other words, you don’t really need a house wrap. A WRB does three things: blocks air, blocks water, and slows vapor diffusion while still remaining vapor open enough to provide drying potential.
Plywood by itself is an air control layer. Just hold a piece of it up to your mouth and try to blow through it. Plywood is also a Class III vapor retarder, even without any paint on it. It has a perm rating of about 2. The paint then takes care of the third component by creating a water control layer. Throw a bucket of water on painted plywood, and it’ll just roll off.
I’m sure there are plenty of house wrap manufacturers and sales reps that would love to disagree with me, but I just can’t see how there’s really any difference. Considering most house wraps have a perm rating above 10, and questionable air and water tightness, I don’t see how they’re any better.
Most wraps are also UV sensitive. If exposed to sunlight for too long – as little as a few months or less – they start to breakdown from photo degradation. Paint, on the other hand, is much more UV stable, and actually protects wood from photo degradation.
You Must Use the Right Kind of Paint or You’ll Create Problems
I know this might seem trivial but if you don’t use the right kind of paint, you’ll probably do more harm than good. I think it makes no difference if you use interior or exterior. We’re talking about framing and sheathing, this stuff isn’t going to be exposed to the elements for 20+ years – hopefully.
It is, however, important that you only use water-based latex, no glossier than semi-gloss. If you use oil-based or glossy paint, you’re putting a Class II vapor retarder all over your building assembly, which means it’s definitely in a lot of the wrong places.
This is a problem because you’ll more than likely accidentally trap moisture in your walls or even in the wood itself. That’s a very bad thing.
My preference is semi-gloss, but satin and flat are also just fine. I just happen to think semi-gloss is a bit better at water repelling. I also like to use white paint, but not because it’s a radiant barrier. White paint is not even a radiant barrier at all. It reflects about 80% of visible light, which is why it stays cooler than other colors, but it still absorbs over 90% of UV and near-infrared waves.
I just like white because it’s visually clean – easy to see what’s going on, find fasteners, and so forth – and I can also write on it with any color pen, pencil, or marker I happen to have on me, and easily see what I’ve written. It’s also cheap.
If you’re on a tight budget, though, feel free to use any color from the clearance rack at your local home center store. Any place that mixes paint should have a shelf of all the paints that got messed up or rejected by the customer. They usually mark them down to as little as $1 or $2 per gallon.
I know this is an uncommon practice, and most people aren’t going to bother; but as long as you have the patience, I believe it’s worth the extra effort to paint your framing lumber. It’s also not as time consuming as you might think. I can paint seven studs in an hour, working at a normal pace. That’s 56 studs in eight hours, which is actually quite a lot. That’s enough studs to frame seven 8×8′ sections of wall with 24″ on center spacing.
Hopefully, I’ve convinced at least one other person out there to do this, so I don’t look like such a weirdo.