Mold Remediation

[mayhem]

Anyone have any experience in dealing with mold indoors and remediating not only the mold, but also the cause? I've got a funky smell in the house and just the other day I looked up and noticed this huge black smear coming through the master bedroom where the ceiling meets the wall. Its mold and I have to kill it. Years ago before we painted the rom I had a spot there too, I cut it out, couldn't find anything else and chalked it up to mouisture inside the sheel from construction...cleaned it all up and went on my way...well its back now so obviously I've missed the cause so I need to fix it.

Some background info. House is pretty new. Log cabin kit assembled weathertight by a certified log cabin guy. Project was completed in Dec 2002 and we moved in in January 2003. The mold is right next to the master (upstairs) bath (I'll get some photos tonight). I strongly suspect at least part of my problem is inadequate ventilation. The bathroom vent fans are plumbed outside, but there is no actual vent exhaust installed...rather they both (first and second floor bathrooms stacked on top of each other) are run out to the soffit vents under the eaves of the roof. Cool way to hide them and not clutter up the exterior of my house, but I suspect that each one is a round 4" tube that is just pushed up against what is effectively a 4"x1.5" rectangular opening, likely resulting in about half of the vent pipe being covered up and probably venting some of the air back into my house...effectively pluming moist air indirectly into the living area and whats probably worse, directly into the space between the floors and inside the roof rafters. I surmise this is so because I have these charming little dust bunnies on the wall near the ceiling in the first floor bath, they're about 4-6" down the wall from the ceiling and more or less directly below where the exhaust vent goes out to the soffit...when the vent fan is runing I can see the dust bunnies moving in the breeze and I cna feel a steady stream of air coming out of the area where the ceiling meets the wall...that stream of air goes away when I turn off the vent fan. The second floor exhaust is setup in an identical manner, so logically if one is creating backpressure into the house, the other might be too...but the celing is better sealed in the upstairs bath (its all sheet rock and downstairs the wall is log so it needs trip to seal it up properly)...so if that secodn floor exhaust can't push moist air back into the bathroom itself, its probably going into the rafter area and dumping moisture into that area...thus causing the mold.

So I need to get opinions on how to best track down the root problem and fix it and what to do with the mold I've got. Wash it with bleach or something? Some other anti-mold product? Cut out the infected material and patch the holes?

I want to do it right and fix the problem, but this is strictly DIY, I simply do not have the resources to hire a professional.

 

[Highbeam]

Cut out the bad sheetrock. You need to dry out the wall cavity. While it is open, check out the cause. Sheetrock is cheap to work with but takes some practice to make it look good.

I would definitely terminate the exhaust fans with the proper termination outlets. This can done in the soffit or on the roof but the outlet must be the same size as the 4" pipe. Bathroom ventilation is extremely important.

Have you ruled out roof leaks?

 

[mayhem]

While I can't rule out the roof 100% yet, I've been up there repeatedly to check for leaks and to clean the chimney, never even a shingle out of place, no obvious damamge, no torn strips or anyhting obvious...which means exactly nothing of course. Additionally I have no discoloration on any sheetrock anywhere...except for the moldy spot. Not concrete proof, but the lack of brown discoloration says I probably don't have a leak.

The more I think about it, the more I think it has to be the vent fans. When I cut the sheetrock out I'll run the fan and see if its pressurizing that area. Ought to a good indicator.

 

[Wet1]

Sounds like a water leak to me. Could be external or internal (leaking water pipe, drain, baseboard circuit, condensation from cold water line, etc.)

 

[blades]

A the previous poster said plus if your vent line is in a unheated area, during the cooler times you will get condensation in the vent pipe. This can leak out contributing to your problem. The vent line should be insulated.

 

[mayhem]

Pics of the damage. After looking around the web of some pics of bad mold damage, this doesn't look so bad. Time to kill it while its still not bad.

 

[peakbagger]

Running exhaust vents into the soffits is a popular but potentially risky shortcut that builders take. If the ventilation in the attic is working properly air is continously flowing up through the soffits and out the ridge vent, therefore any moist air is pulled up into the roof and depending upon the temperature of the roof deck, will condense into liquid on the cold surfaces. It will usually freeze in place then drip down into the insulation when it warms up.

The other issue is that you may have a vapor barrier issue and a gap in the insulaton system in the mold area. On conventional construction the top header and plate of the wall has no insulation between the outside and the inside, plus on many insulation installations, the insulation in the wall has settled leaving a gap in the insulation. This leads to a cold pocket up at the wall to ceiling joint. Not a major problem normally, unless there is no vapor barrier and the area has a high humidity level. If either are the case, dampness will find its way through the sheetrock and condense on the underlying wood and mold will frequently form. If the vapor barrier is unknown, there are paints that can be applied to the face of the sheetrock that acts as a vapor barrier.

 

[d.n.f.]

Just helped my neigbour demo his second floor deck. Bathroom vent was vented into the soffit. Talk about mold and rotten wood. Yech.
My house has two fans that vent into the soffit. They will vent through the roof when I change it out next year. After seeing that damage especially.

 

[fbelec]

most of the building inspectors that i run into on jobs here in mass see a vent in the soffet and fail the job. if your fan is running and the roof is seeing sun on it then it is pulling air in that same soffet to get let out up at the ridge vent or gable vent or power venter. so yes that humid air from the shower is coming back into the house. guys i know that have to deal with mold say that the only thing that really kills mold is straight bleach. go up in the attic on a rain storm and double check that it's not a leak. i just repaired a couple of small holes at my chimney flashing that would leak water in to run down the rafter 12 feet before it dripped down on the insulation and my ceiling.