Detecting Beam Rot
Determining the presence of dry rot is important, but the search can be frustrating, and the situation confounding. Dry rot may not even be outwardly visible. Numerous applications of fillers, caulking, and/or paint over the years can mask underlying wood decay. But you can bet that the lack of regular maintenance using these same products will guarantee creating the very problem you're trying to prevent. Go figure.
First, it's a good idea to begin regular inspections of your roof beams (every year or so is a good place to start). This will allow for the discovery of deterioration problems before they become severe. Consider having a qualified licensed contractor perform these inspections.
What Does Dry Rot Look Like?
There are some telltale signs to watch for when looking for rotten beams. Old filler or caulking in cracks that has become dislodged or separated presents a risk of water penetration. Discoloration, staining, or peeling of the existing paint coating can be indications of moisture problems. Beam-ends that are spongy or crumbling, have unnatural voids, or have taken on a marked distorted shape, are exhibiting symptoms of advanced decay. Fungus growth can appear on the beam surface, if there is enough moisture. If you ever see a mushroom (the fruiting body of a dry rot fungus), you definitely have an issue!
To see more images of signs of dry rot, click the top photo to expand and read the explanation. (On some iPads, you'll need to use a slow double tap.) Use the arrows within the expansion to read flip-book style. (On mobile devices, tap and swipe left.)