Roof Beam Dry Rot

In new construction, some drying-related end-cracking and shrinkage is normal with roof beams. Larger splits and warping can also occur during this period. But openings of any size, especially at the outer end and top, are notorious for quietly channeling rainwater deep inside the beam. Over time, this cycle creates a condition that promotes the growth of wood-destroying fungi. Dry rot (also known as wood rot, brown rot or wood decay) is the byproduct of this growth.


The term "dry rot", often used informally to describe decaying matter in wood (as it will be throughout this site), is a little misleading. Wood must be moist to decay, even though the rot can periodically dry out. The growth of this kind of fungus rot depends on food (wood), water (condensation, rain), air (oxygen), and moderate temperatures. To eliminate any one of these is to eliminate the growth; the obvious controllable factor is moisture. In fact, under ideal conditions (i.e., dry), wood beams would last indefinitely. 


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.)