Several houses around town (NE Kansas) have what appears to be mildew growing on the exterior siding. It’s usually worse on the north side of the buildings, although all sides may be affected. Our church parsonage is one of these. Two storeys, wood frame, built in 1923, insulation blown in during the 70s. An upstairs window was closed in during the 90s, the siding here remains free of the mildew–a clean rectangle framed by the other siding with dark stains. A couple of upstairs bathrooms have ceiling fans that vent into the attic. There are soffit vents, but may be inoperative, such as having insulation over them in the attic. I’m wondering if the mildew is indicative of moisture or damp insulation within the walls behind the siding.
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Replies
not good
I'm no expert, but I'd say this is not a good sign. If the mold is on the outside, there's a good chance it has migrated there from the inside. I'd talk to a building inspector and/or a mold authority, since there could be occupancy health issues.
Soffit vents or not, bathroom vents should never be vented into the attic. I'm sure building code requires them to be vented directly outdoors. Prpblems include mildew in attics, and condensation of moisture on insulating, greatly reducing it's effectiveness.
I'm not at all sure that correcting the venting issue will solve the entire issue of exterior mildew. Factors include how vapor barriers relate to the insulation, whether the proper joints have been caulked, or not caulked, etc. I'd say it would take a really knowledgable person doing a detailed inspection to really track down the solution and to see if the impact is greater than what is visible.
Soffit vents or not, bathroom
Delete this double post.
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