– Do termites like redwood?
– What makes wood susceptible to termites?
– To be Followed by: Termite Prevention
This article series is a summary of years of construction work observations.
Termites are not the only wood-eating pests, but they do the most damage to homes in Southern California.
There are two main classes of problem termites in Southern Califonia (and the country): drywood termites and subterranean (underground) termites. The drywood type is seen much more often and likes wood with low moisture in it. Subterranean termites live under ground and like moisture.
To get to wood subterranean termites will make a mud tube or tunnel going up across the concrete foundation to the wood. They are usually known by their tubes and which are hidden under the building. Sometimes they are visible on the outside of a foundation or inside a house. You can do an internet search for pictures of all this. As they are less common in my experience than the drywood type I am not certain but I do believe that they prefer the same wood as the drywood termites do (more on that later). I do know that by far most boards in most houses do not have termites. But I also have seen sections of many boards of house framing destroyed by termites – enough that I was wondering just what was holding up that part of the house?
There is a datum that most people have heard: Termites will stay away from redwood and cedar. But is it true?
As a contractor, I believed this too. Until in one year, about 10 or 15 years ago, I saw three redwood decks at three different houses in the Los Angeles area. These decks had been pretty well demolished by termites. Either termites had changed their dietary preferences, or there is more to the story. Or both.
A few years later I overhauled another house with two redwood decks. The redwood ALL needed replacing, due to rot and termite damage. However the important lessons were not in the redwood, but what I observed in the supporting joist boards.
I had always wondered – why do termites eat some boards, and not others?
Most of the wood under a first floor – above a crawl space, and most of the wood in an attic, is completely accessible to termites. Actually, given that termites only need about a 1/8″ gap to get to a board, most boards in a house are accessible to termites So why (by far) are most boards on most houses termite-free? (They don’t get a chemical treatment when they are built!)
The joists in that last house mentioned above ran under the floor and stuck out over the hill. The decks boards were laid across them and nailed in. As this was an older hillside home – by L.A. standards – the joists were fully exposed under the house. This is where it gets interesting. In board after board, the termite damage only went back about six or eight inches under the wall of the house. Only one board had termite damage about two feet back, but the rest, some 30 boards, only had damage under the house 6-8″ back. But where exposed to the weather, they were all damaged to the point where it was dangerous to walk on the deck.
WHY did the termites stop?
Visit my next post (next week) where we will explore the answers to these questions.
Copyright 2013 by Brandon D’Rion