Originally Posted by oldog/newtrick
My 1st inclination is a moisture problem inside your house. How many people in your family, do you take a lot of showers and do a lot of laundry? Is the dryer properly vented outside? Is the ventilation of your roof properly installed? It doesn't look like a shingle leak to me. A roof leak would be showing up in the ceilings inside also. A leak at the eave would not show up as seen in the photos. Can you show a picture of the attic decking and any vents that are visible from the attic?
I belive oldog is absolutely correct. I noticed dark looking water stains under my soffits as well that just showed up recently. I thought I might have a roof leak, but it seemed somewhat unlikely considering its a fairly new house, less than 10 years, anyway, and the stains were at a few locations. Recently, I replaced an exhaust fan and when I got up in the attic, I found that both of the 2 exhaust fans had no venting on them whatsoever! Note: We have owned the home for 3 years now. I did a little research and found one article that led me to belive that this lack of ventilation was causing the stain. Then I found this site and between the pics of the original problem and oldog's post, I'm convinced. I ran some flexible 4" hose tonight to the soffit, but I'm going to call someone to install the actual soffit vents. I'd rather pay a little extra to make sure I don't end up cutting a joist or something.