Siding and soffit staining

Any opinions what causes this? The pattern is different than others I have seen.

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I’ve seen unusual staining on siding on soffits, and after looking more, I realized there was in the vicinity of humid discharges. The moisture condenses on the first cool surface, and then collects dirt. Bathroom vents in soffits, or something is venting directly into the attic, and then exiting the gables.

Just a guess…


Was there any sign of smoke damage in the attic?? Did the home have a fire at one time or another…sometimes it may have been more smoke damage than anything. Just Asking?

You’ve got yourself some bath fans or dryers venting into the attic, without a proper vent cap terminus.

I’ve seen several black smoke damaged siding material at gable end vent areas.

Most are caused from improper firing of an oil fired heating system. Black smoke rises through the living area, then to the attic area where it vents out of the gable end vents and builds up onto the siding.

Your stains are brown, so you must have a different situation.

Ahh… the notable “puff back”. That just happened in a 3 story furniture store near me, and the insurance payout was in the 100’s of thousands of dollars.

Was the roof recently replaced? Many times in older homes when the roof gets stripped off there is quite a bit of dust and it tends to vacate thru the vent’s and soffits.

It appears to be dirt / dust blowing out of the attic space.
It seems to be a lot of air movement out of the vent. It should be able to be rubbed off by hand. If so many times this indicates the roof could use more vents.
Some houses I have seen that were older that have no plastic air barrier placed in the ceiling. This seemed to allow air movement from the house and a lot of dirt around the exterior vents.

Need more info…did you inspect the attic…what did you find…the posts are asking the right questions, likely to be a combination of dirt and humidity getting out any where it can.

Was there any signs of water stains on the wood in the attic?