Why did the termites stop eating six to eight inches back under the outside edge of the house on most joist boards?
Here is the sequence:
1. Continued wetness of wood allows the growth of fungus. This occurs when it rains a lot. This is worse when water is trapped between two touching boards. Fungus rots the wood, making it soft. Rain does not fall under a house, so those parts of the joists remained dry and hard at all times.
2. Termites prefer soft wood. They even like soft redwood. This is the most important lesson in this series. When they find soft wood, they come and feast.
What other evidence is there that termites like soft wood?
A. Pine is a really soft wood. Termites are often found inside indoor pine moldings such as door and window casings, and baseboards, even when these have never been exposed to water.
B. They rarely attack house framing, especially fir, that has not been softened by water and fungus. House framing is usually fir, which is harder than pine or redwood. When they do attack a house framing board they usually leave most of the nearby framing boards alone. Based on the above, I believe they choose the softest ones. Of course a leak can result in many boards being softened. Besides a roof leak, a leak can just be – the wall or the trim around a window or door was not maintained, or poor quality caulk was used, which cracked, and water gets into the wall every time it rains.
C. I have rarely seen a termite in a sound oak board. Oak is much harder than fir.
So do termites like redwood and cedar? If in good condition, termites usually leave it alone. So it seems to last longer IF it is not set up to soak but can dry out when it gets wet. That is true for other types of wood too. Air on all sides works wonders.
The above observations apply for sure to drywood termites, and at least some of it applies to subterranean termites.
After I wrote this, I discovered a website, by an exterminator who discusses the resistance of various woods to termites. He says, in the comments, “The only thing I can tell you for sure is that the harder the wood, the more resistant it is to termites.”
What I have added to that recognition is that water and fungus makes the wood soft, and termites then get a lot more interested in almost any wood.
Visit my next post (next week) where we will look at Defending Against Termites – When Building.
Copyright 2013 by Brandon D’Rion