Attic Ventilation - Help! Got Mold!

[Dan]

Hi, I went up to our attic to store some items the other day and was overtaken by the smell of mold/mildew. I looked around on the trusses and roof planks and they are relatively covered in white/black mold. Our house was built in 1930. We bought the home 6 mos ago and the previous owner said he put on a new roof less than a year ago.

He installed some low cost ridge ventilation (the stuff looks like corrugated cardboard) from Owens Corning (I think). Although, because of the way our home was built originally, there were no soffits that are accessible from the attic. The roof line connects to the outer wall where it meets the floor. The roof then continues past the floor on the outside of the house and the soffit is below the attic floor.

\\ \\ _____\\ I \\ I_ \\

I think you get the point. So, it's not possible to have soffit vents. (at least I don't think). There is, however, one window at the end of the house (typical rectangular colonial approx 25 x 40). I pulled out the window and installed some plywood and cut out an opening for a gable vent and a ventilation hole for the bathroom ventilation fan; which, was originally not piped to the outside and has now been blowing humid air into our unventilated attic. Now were having fun.

So, my question is, I have installed one gable vent, the house has a cheap ridge vent system, I have corrected the ventilation from the bathroom fan to exhaust out of the house, so, should I install another gable vent on the other side of the building to allow for crossflow or is this not going to work with the ridge vents?

Also, any mold remediation recommendations will be greatly appreciated.

[m Ransley]

You might have fixed the issue if you ran the bath vent excessivly in summer. The mold should have died over the summer if it was just a vent issue. I would get a garden sprayer maybe 5 gallons of laundry bleach and spray the mold to kill it. If you dont kill it you wont know if you did enough to fix the issue. If it comes back you know you need more venting, If you just leave it the mold will die but all the spores might cause you issues, so kill it with bleach. Opening the other side sounds easy enough, are you sure it wasnt open before.

[Dan]

I wish I would have corrected it in the summer BEFORE we got to this stage. But, I wish I had the winning lotto ticket as well.

Is spraying it with a bleach solution enough, or does it need to be wiped down also?

[pawlowsk002]

Dan:

You'll need to scrub. Gear up with goggles and a mask, and some long rubber gloves (Clorox isn't ultra-hazardous but it will make the hands pretty sore) and a stiff-bristled brush, then take a bucket of hot bleach water and scrub the mold away. Open the attic windows and use a fan for ventilation of the

bleach fumes. Don't mix the bleach with anything except water. This is how my brother & I removed an assortment of mold from roof joists in a poorly vented house.

Two questions: is this a finished attic? Is it insulated, and where? Is the floor insulated, or the roof, or both? As I see it your best course for an unfinished attic is to insulate the floor well, with the vapor barrier down, toward the living quarters, and make sure there aren't any openings into the tops of the downstairs walls where air can infiltrate, then ventilate well. Soffit vents would be nice. Is there any opening into the soffit areas at all? Can you see into them through the spaces between the rafters?

Moving the bath vent was a good move. That will cut down a lot of moisture. You also get moisture infiltration from downstairs, through the walls and floor. Warm, infiltrating air holds lots of moisture. It hits the roof, cools, and drops condensation on the wood. Mold grows. The house I was working on was uninsulated except for blown cellulose in the floor, unvented, and finished with pink-painted fiberboard. Mold was everywhere, and everything up there felt damp and clammy with condensation. We insulated the short side walls and roof, using rafter-mates to keep an air space by the rafters, added box vents on the roof and gable-end louvers to let air into the eaves. This cured the mold, but was only a partial solution - the eaves were partly over the 2nd floor ceilings, making those ceiling areas cold where I'd removed the blown crud in rewiring a few circuits. I should have taken up the floorboards and laid down fiberglass there too.

[Mark]

I agree...

3 steps

1) spray and scrub with bleach

2) increase the ventilation in the attic 3) seal the attic floor so that no warm moist air from below can enter the attic...

Mark

[m Ransley]

Don`t scrub, its a waste of time. Bleach kills mold, it will only come back if conditions allow it to. Mold spores are everywhere but only grow in the right environment, and for your attic excessive moisture is what you need to stop. You can`t stop mold spores from re entering, so you need to vent properly so they don`t grow.

[Dan]

Thanks for the replies.

The attic is not finished anywhere. The attic floor is well insulated but, it does not have a plastic vapor barrier underneath the insullation. And, no, there is no daylight to the soffits. the soffits hang off the house. So, the soffit vents are a no go.

My concern with bleach is that it only works on "non-porous" surfaces and does not kill the mold. I have read in another post by someone who claims to work in a mold testing lab, that using a quaternary ammonium compound works. A product that has this compound is called "Steramine" sanitizer tablets. Has anyone used these before? What concentration would work best?

I guess I just want to make sure I'm not going to keep having the same issues after scrubbing this place down.

[buffalobill]

[Stubby]

The second reference site has old articles -- the most recent was 2003. However, I'm an ardent listener of Dr. Dean Edell on TalkRadio. His reports recent studies (2006) that minimize the effects of mold. It's is everywhere but really doesn't harm people except in rare cases. Just another "Mass Sociogenic Illness" that so many of us panic over.

buffalobill wrote:

[tnom]

The above contains ammonia. If you use this make sure it does not mix with chlorine. Deadly chlorine gas will develop along with other dangerous gases.

[m Ransley]

Alot of things will kill mold, bleach just happens to be the cheapest, is easy to use and fairly safe.