New Roof Problem

I recently had roof replacement on my modular home. It did not have a roof vent before, but roofer said we needed one because plaster on my ceiling was cracking and falling off. A plastic shield was placed, then shingles and a roof vent. Now I have mildew growing in corners of some rooms and the plaster is really coming down. Also my home seems stuffy. What should I do!

Dehumidifier, wash all the walls and allow some airflow behind furniture. Where is the mildew showing because it’s likely your indoor environment and not the roof. Do you do a lot of frying?

I don’t fry. The mildew is in the corners of rooms. It didn’t show up until after the roof was about 8 months.

Mildew coincides with high indoor humidity. You’ve suggested this is showing up in several rooms? I often see it in homes that are inadequately ventilated and/or have cold spots on the walls due to poor insulation. Post some pictures and share some details on the type of modular home, the roof type, age of the structure and your general locale. Some very experienced contributors on this site might be able to help you with your dilemma by offering an alternate diagnosis. Good luck.

Do you have exhaust fans in the kitchen / bathrooms? Check for loose plumbing vents and any ducts or vents for fans as they may have been compromised.

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Good idea, Dark. We’ve had the flex duct fall off the vent unbeknownst to us before, customer spotted it when retrieving holiday decorations from attic. Easy fix and generates customer good will.

I do have vent fans in kitchen and bathroom. My duct work for AC under the house. Would I need to go on the roof to check vents for fans?

Modular construction is notorious for mold. Depending on how the modular was constructed adding additional ventilation could have allowed outside humid air in without letting it exhaust.

Unfortunately a lot of roofers don’t understand ventilation and condensation and just assume a roof without ventilation should have it.

If you are convinced that the vents are causing the issue, close them off and de-humidify, clean the areas, and see if it comes back. If it does not, then permanently remove the vents.

The fans should be in the house. The question is if the ductwork is connected, properly attached and vented outside. Being a modular, I’m assuming there is no accessible attic space.

I’ve got pics of a roof completely destroyed by a dryer vented into the attic.

there is no attic space. indoor ceilings are vaulted.

The only logical supposition from the given information is a change in the interior ventilation exhaust. Previous powered vents, bathroom/kitchen, are compromised or completely sealed.

Before you do anything, you need a humidity reading in the house. I would check it in the areas of concern. They are cheap. Your reading shouldn’t be over 60.