Log Cabin Chronicles

Royal Orr

Watch it rot
or, spare the caulk and spoil the beam


The paint on the window trim was peeling. So one weekend this spring I dug around for a scraper and brush and found a can of exterior latex that was still half full. But when I pressed the scraper to the wood trim board, it sank through the peeling paint into spongy rot beneath. Intimations of my home's mortality.

I built my house when I was a young man. It was slapped together with a lot of dash and very limited cash. I understood the importance of caulking and flashing and ventilation in a theoretical sort of way. But mostly I was just trying to get something built on a very tight budget.

To my present regret.

Wood rot is interesting -- and very common -- stuff. One estimate suggests that as much as 10 percent of the structural and finish lumber that is produced in North America is used to repair the effects of wood rot in existing structures.

There are two main types of rot, according to the experts. The stuff on my window board belongs to a large family of wood rot fungi that are usually white or yellow in color, and make the wood stringy or spongy in texture.

The other group causes dark brown discoloration on the surface and breaks the wood into brown chunks or cubes on the inside. I have some of that in a wooden post in my basement.

Decay fungi are living organisms that send tiny threads called hyphae< through damp wood, taking their food from the wood as they grow.

A scientific paper I read on wood rot explained the process in this way: "The fungal hyphae penetrate inside the cell walls of the wood and produce large cavities in the surrounding cell wall matrix."

"Large cavities" are not good.

And as for that brown rot in my basement, it's probably Gloeophyllum trabeum. For the last few years its "plasma membrane regions" have been spewing "low molecular weight phenolic chelating compounds" into the cell walls of the spruce 8 x 8.

In a word, my little brown friends have been quietly digesting my structural timbers.

Moisture is, of course, the problem. Keep out the moisture and you keep out the rot. My failings as an amateur carpenter have caught up with me.

As the works of my youth crumble about me, I cry out to the next generation: Give heed young carpenters and wood butchers! Do not deny the benefits of fresh caulking nor disdain the mighty power of flashing!

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Copyright © 2000 Royal Orr/Log Cabin Chronicles/06.2000