From metal roof to composite shingles, mold and water issues?

Question

So we had our roof replaced in 2007 from a ribbed metal roof to a comp roof. We also live in Washington State in a gambrel roofed home with no duct work and about a 4' by 12' attic.

During the tear off, the metal roofing and stringers were torn off. Then sheathing was layed down, followed by paper, ice dam and shingles. Beautiful roof right!

Fast forward six months later, I was fetching something out of our small attic and there was standing water and mold under the visqueen. It was horrid and I was less than thrilled. So I called the roofer and he sent a dude out and he yoked out the bad stuff, painted the entire attic with Kilz and replaced the insulation, A few weeks later a few of them came out and cut in a ridge vent. Cakes and rainbows right?

Now, there are dark areas showing up on the ceiling where the rafters are. The only thing I can think of is that the rafters are getting wet.

So my question is what are the chances that the rest of the insulation is in as bad of shape as what I saw in the attic? Am i looking at a huge mold problem?

Also, before the sheathing was put down, shouldn't the stringers have been replaced as well? Without the stringers, wouldn't it be a giant dead space with no circulation? Looking from the inside, the layers are drywall, visqueen, insulation, sheathing and roofing. I would assume there is no air circulation.

There are a few roof vents but I'm not sure how effective those are either.

Any suggestions? Should I call him up after six years? Is this an insurance thing? Should I track down a mold inspector?

Any help or guidance would be greatly appreciated.

R, Zac

Answer 1

Any moisture issues related to the standing water incident would have manifested itself long before now. Whatever the current issue is, it's unrelated to the previous issue. In that time, it is possible a new leak developed. It's also possible the dark areas are related to interior humidity and unrelated to the roof. In cold weather, the ceiling surface under rafters is measurably cooler than the nearby portion under insulation alone. This can cause condensation only under the rafters. As you know, condensation can lead to mold.

Can you tell if the darkening is due to actual mold? The damp surface can attract dirt that darkens the area even though no mold is growing. Even though the dirt can stain, attempting to clean an area with plain soap and water would yield a very different result than if mold is actively growing.

If mold is actively growing, it is time to consult with a mold professional. They will determine the cause, mitigate the mold, and suggest how to prevent it from happening again. If you want to investigate further before going that route, the only reliable way to determine if the rafters are getting wet is direct inspection.

Cut a small inspection hole where you think it's the worst. If it's wet up there, a lot more ceiling is coming off, so don't bother patching the hole. The roof is leaking. It needs to be repaired and all wet drywall and insulation needs to be replaced. If it's all dry, breathe a sigh of relief. The need to patch the hole is much less than it could have been. Be sure to adequately seal the damaged vapor barrier.

If the rafters are dry, the only thing you can do to reduce condensation on the ceiling is reduce the overall humidity of the house. First try selective ventilation and lifestyle adjustments. Consider bumping the thermostat up a bit. If that's not enough, look into continuous ventilation through an air to air heat exchanger.

A far as replacing stringers, that cannot be done with comp roofing unless a full cold roof is installed. It is normal practice for concealed structural spaces filled with insulation to not be ventilated. It sounds like the roofers followed conventional building practice.