Hope you can help me once again. I noticed that the plywood ceiling of my attic is discolored black.. I am assuming it is some form of mildew. The plywood and shingles were replaced about 7 years ago. I have about 6 inches of fiberglass insulation on the floor. There are two roof vents, a ridge vent and we placed soffets under the roof overhang. Any ideas?

-- teresa (teresam@ascent.net), May 04, 2002

Answers

I believe you need more ventilation if the mildew is all over the place,if it was just in one spot it would a leaky part of the roof.I have the same thing in my unfinished upstairs.Make sure the area by the soffit leading into the attic is not covered or blocked by insulation so there is good air flow.Most likely you will need install a power attic vent(fan)to pull or push the hot moist air out. Good luck. Dave (central WI)

-- Dave (duckthis1@maqs.net), May 04, 2002.

After you deal with the moisture and ventalation problem, wash the mildew with bleach solution to kill it. Dryness just makes it go dormant and some of these black slimes put off toxins when they bloom.

-- Laura (LadybugWrangler@somewhere.com), May 05, 2002.

Have you checked to see that your 6 inches of insulation is not blocking exit of moisture along the wall-roof interface (not sure of the proper name here)?

-- BC (desertdweller44@yahoo.com), May 05, 2002.

With the exception of a fan, it seems that you'd have more than enough ventilation in your attic. It might be worthwhile to check out the area during a long rain.

I know in some areas where builders have gone with foam and stucco as an outside finish on expensive homes, there have been severe problems with water getting behind the surface and rotting the wood and creating mildew problems.

You have moisture coming from somewhere unless you live in a humid area and it's condensing out from the air. More ventilation might help. As another posted make sure the openings in your soffit aren't blocked by insulation.

-- Darren (df1@infi.net), May 05, 2002.

light will help retard mildew-in our basement we use a combinations of fans and open windows for air circulation, plus leaving lights on occasionally-mildew likes the dark. Mostly it is a moisture problem.

-- Kelly (homearts2002@yahoo.com), May 05, 2002.

I can speak for mildew in winter, but have no experience with humid summers. In winter, the moisture is most likely coming from inside the house, thru cooking, breahting, bathing, etc. It condenses when it hits a cold surface. If there is an nsufficient vapor barrier in the ceiling, the moisure will typically condense on the ceiling joists, often near the middle of the insulation.

I'd check down in the insulation and see if there is any sign of moisture or mildew there. If so, you need a vapor barrier. If you have plaster or sheetrock on your ceiling, something as simple as pva primer paint (that's poly vinyl acetate, or something along those lines) This pva forms a pretty good vapor barrier.

If you have a wood ceiling, it's a bit more difficult. You'd likely have to pull up the insulation in the attic, lay out six mil visqueen over the top of the joists, dipping down in between them, then replace the insulation. Big pain in the rear. But you really want to be sure you don't rot out your ceiling joists, or your rafters and sheathing!

-- joj (joj@home.org), May 05, 2002.

. . . and be sure to take care of the problems, as Laura mentioned above. We just renewed our homeowners insurance policy, which the company had just reworded. They will not pay out for "Mold damage" due to the number of excessive claims. In fact, most any problem that occurs with a house having a long term problem and the owner knowing about it will not be able to make a claim. Insurance company will only pay out for sudden and catastrophic occurances. So if you get a renewal with the company telling about some changes, definitely pay attention and ask questions. Dave has the right idea; not enough air flow seems to be ventilating you attic. Good luck with your solutions.

-- j.r. guerra in s. tx. (jrguerra@boultinghousesimpson.com), May 06, 2002.