I was shocked when our timber framer, Mike Yaker, urged us to forget painting the inch-thick oak boards on our new barn. To me the prototypical barn was barn red. I have always loved to see red barns. They look great against a background or green fields, golden wheat or sparkling snow.
But the natural golden color of our barn siding was gorgeous. The grain of each board was a masterpiece of pattern. Mike said the oak would weather to a silvery gray and would not degrade any faster without paint.
I did a little research and found that according to the research from the Forest Products Laboratory in Madison, Wisconsin, oak does just fine without a finish.
All woods will change color quickly under the harsh glare of the sun. Within a few months, the surface turns every tone of gray, but a few millimeters under that silvery hue, the wood is unchanged and unaffected. Wood’s marvelous elasticity and compressive strength are not affected by surface weathering.
I realized that gray was the new green.
By not painting our barn we have avoided putting a lot of toxic stuff into the world. Most of the products used to coat wood contain volatile solvents and other toxic chemicals. They are added to improve performance and durability, and if you use oil-based paints, the clean up is another toxic solvent. The list is long and nasty.
1,4-dioxane and acetaldehyde are suspected carcinogens. N-methyl pyrrolidinone is a reproductive toxin. And aromatic solvents such as toluene and xylene can cause a number of health problems. Just think about all the lead-based paints people used to use. Some of the substitute metals in current paints aren’t much better.
These materials are chipping and falling off the wall surfaces and settling into the soil, where they will be toxic for a long, long time.
And speaking of long time, that is just what your exterior wall coating is not going to last.
According to Tips by Real-Estate Agents, here are some average time frames for an exterior coating:
Latex paint — 5-7 years
Oil paint – 6-8 years, depending on sheen. (Semi-glossy surfaces will last longer.)
Semi-transparent stain –3-4 years
Solid oil stain – 5 years
That silvery finish of weathered wood is looking better and better.