Do my Old Wood Window Sashes have Dry Rot?

Some people think of dry rot as unprotected wood that has been exposed to the elements and contains large checks.  This wood is usually still structurally sound.  The checks can be filled and the fibers reinforced to save the wood.  We think of dry rot as powdery or mushy (so in this case not really dry) wood that is no longer viable.  This substance must be removed and replaced with new wood fiber in the form or a splice or dutchhman, or entirely new component — or filled with restoration-grade epoxy.  The examples above show wood with a degraded finish – not dry rot.  The wood fiber is still in good shape, it just needs refinishing.