The woes of building with wood products

By Tom Gocze, BDN Staff
Posted Aug. 14, 2009, at 7:01 p.m.

I like working with wood. Some days, I hate building with wood. This past week makes me think a lot about why we build with wood. Many of our current wood building products are fraught with woes.

Here is this week’s tale of woe.

I removed some of the 1-by-12 pine that covers the interior of the building I use for our business. We were going to do some simple renovations. Once the wall covering was removed, there were rotted studs, sills and sheathing.

The way the building is constructed, there is rain runoff that channels off a large roof, onto a smaller roof and then onto a small “doghouse” that protects an oil tank.

The runoff then was pushed directly onto the wall that I had just opened up.

This summer did not help matters any and the wall was mostly humus, along with live worms that were about to have their ecosystem disturbed.

We were able to rebuild the area, using pressure-treated lumber and covering the area with Ice and Water Shield to help keep future runoff from it.

The real solution is to install gutters and manage the rainwater, which we also will do.

But that is not the point of this article. The point is that wood houses decay when they get wet. Duh.

In 2009, the wood that we use for construction is terribly susceptible to rot and mold. The wood is fast-grown. This rapid growth does not impart rot resistance. And the least rot-resistant species are the fast-growing ones. Oriented strand board, or OSB, which is usually used for sheathing buildings, is made from a rot-susceptible species that is made into flakes and glued back together into sheets. The smaller pieces make it simpler to break down when it does get wet.

On the inside of buildings, drywall is composed of gypsum with paper facers to contain it. Joe Lstiburek, a noted building scientist, calls this food for fungi that have no teeth. Look at drywall with humid thoughts and it gets moldy.

We can do better than this. And we slowly are.

It is inevitable on a planet that has rain and wind and snow that water will leak by all our protective schemes and eventually rot some part of a wood structure.

Someone comes along and does some construction that is marginal and water creates the perfect recipe for bugs, rot and mold.

I guess the good news is that it keeps carpenters busy, and without stimulus money.

This has got me thinking about alternatives when building. I have always felt that pressure-treated lumber, or PT, is a unique product that affords us more protection than we appreciate.

I suspect that pressure-treated lumber was created to help sell fast-grown southern yellow pine species that are particularly liable to rot.

PT lumber is usually relegated to sills, decks and other areas where it might remain wet. There is a 20 to 30 percent premium cost for this material.

As I was rebuilding the wall last week, I was wondering why we would not use this for the whole building, since it could eliminate the problem I had run into and make wood structures more durable.

There are a couple minor reasons that I can come up with. First, PT lumber is usually wet. Since it is fast-grown, it is left wet because it will warp and twist all over the place if dried. So it is usually sopping wet and heavy because of that.

Second, the current generation of PT lumber uses copper as its primary preservative. This material is aggressive with fasteners. Steel, galvanized and hot dip galvanized fasteners all corrode quickly when used with PT lumber. The only fastener that seems to hold up is stainless steel. Stainless fasteners are about twice the cost of other fasteners. I’ve used anodized fasteners, but I don’t feel comfortable that they will stand up over time, so I use stainless.

So we keep looking to places like the U.S. Forest Products Labs and UM to come up with user-friendly, safe materials that will allow us to do more with the wonderful natural resource that is wood, without having to break the bank or ravage the environment.

And no, I will not use steel in lieu of wood. It is a nightmare to make a steel building that can be superinsulated, and wood is still more fun to work with.

And there are no steel mills in Maine.

Questions for Tom Gocze should be mailed to The Home Page, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. A library of reference material and a home-project blog are at www.bangordailynews.com/thehomepage.html.

http://bangordailynews.com/2009/08/14/living/the-woes-of-building-with-wood-products/ printed on September 20, 2014