The ceiling joists above my living room have developed spotty stains and have dripped sticky goo onto the table and floor underneath them. As you can see in the pictures the spots are on the underside of the joists and there are no stains or lines on the sides. If this was rain damage, I would expect more significant leakage onto the floor, stains on the sides of the vaulted ceiling joists and less gooey deposits, but I cannot rule out rain as the cause as we have had significant downpours lately. There are no holes or visible sawdust but I'm wondering if this could also be caused by some kind of fungus or insect.
Does anyone have any suggestions as to what is causing this staining and dripping?
Here is a link to four pics on picasa. The first two show the stains on the joists, the second two show the drip on the table:
Picasa Web Albums - satsujinsha - Ceiling Joist
Thank you in advance for any advice!