What am I looking at?

Hello all, I have question about the wood in this attic. First, let me start by saying I’m about a week and a half into the online InterNACHI course, so I’m not an expert by any means. Second, this attic is in my brothers house, so any advice I can give him is appreciated.

How I got to this point is me reading the “25 standards every inspector should know” #13 on dryer vents. Since I was at his house I got curious and was following where the venting led. I found it running through the attic and roof, all seemed normal except I noticed lent on a box top. I look around to the back and saw the split.

Then I noticed the numerous dark spots, which to me only seem to be on the purlins for some reason, but this is too important to guess. So is it rot caused by the moisture coming out of vent? Is it mold? Termites? Or something else I haven’t learned yet? Thanks for the help.

Matt Stentz

Tree sap.

Google… “Wane”.

Never would have guessed that. Pretty cool, thanks guys.