Mold In My Attic....What?!?...Why Now? HELP!

So I'm a bit stressed right now. I just went into the attic (pull down ladder/stairs) for the first time in a couple of months to grab the Christmas decorations. And what do I find? MOLD!!!!

Okay, so this isn't right. The house is 112 years old and has ZERO history of mold. We bought the place six years ago and there has not been one hint of mold or a history of mold. And now there is mold? Why? Please help!

I'll post a diagram of our houses construction below but I don't understand how there is mold now. The house is uninsulated except the attic. The attic has blown in insulation over the ceiling and roof rafters (knee wall). Last year I added more insulation to the attic. I rolled UNFACED R-19 over the 6" of blown in insulation and added more blown in insulation over the low/settled spots. I did this last around December/January last year. This spring when I put some things away I did not notice any mold.

So why now? About three years ago I put a outdoor vented fan in the bathroom (there never was one). The house has a ridge vent also as well but no soffit or gable vents.

And here is the kicker....the mold is only on the North side. The South side of the house looks fine. The attic is noticably humid. Many of the boxes of Christmas decorations felt moist, kind of like I took them out of a humid basement. We've also been heating our house with a wood stove (newly installed) this year which I would think would dry the house out even more!

So I'm wondering "Why now???" This is obviously a new thing. Any ideas??? I apologize in advance for the frantic post, but I'm a bit freaked out. Having mold in the attic is about as good as putting up a "Leaded House - - Do Not Enter" sign when it comes to resale value.

What do you think.....why now???? Was the addition of insulation a bad thing?

 

Hi BigOldXJ,
Wherever you have cold surfaces, and north will be colder, you need to prevent inside humid air from reaching those areas. Dew point is the key number and inside air at 70° and dry, say 28%, will cause condensation at 35°, its Dew Point. Temperature, Dewpoint, and Relative Humidity Calculator

What is missing is a source of incoming fresh air that is much lower in moisture. This normally occure in the soffits, but with your kneewalls, side vents would work.

Air seal from house to attic and vent the attic. If you want to move that attic space into the conditioned space, then it will need to be insulated and air sealed from the outside and that small attic up top, and a low gable vent added.

Bud

 

Thanks Bud, your post confirms my thoughts on why it happened. But why now? Why after 112 years, is this the first time that mold has taken hold of this attic? I've never felt or seen evidence of humidity up there. This seams to be a first.

Ideally I would place a vapor barrier on the warm side of the ceiling, but thats kinda tough to do now. There would also be soffit vents and an air space between blown in insulation and the sheathing too, again tough to do now.

The moisture seems to be condensing along the entire inside roof surface. I stuck my arm as far as I could down into the insulation along the sheathing and the sheathing felt moist.

So is there an easy solution? Or is the only way to do it "right" to:
- Remove the roofing
- Remove the sheathing
- Install some foam rafter vents on top of the existing insulation
- Install some soffit vents
- Install new sheathing and roofing?

Or am I over thinking this? Just spray some bleach on the existing mold and install a gable vent at each end of the attic?

 

I'm under the weather at the moment so a bit hard to concentrate, but I would think removing the roof would be unnecessary, unless you need a new roof anyway. If there is no insulation in that attic floor, then what you are moving towards is conditioning that space and creating a thermal barrier between the walls and ceiling and the outside.

A couple of thoughts:
1. A good coat of the right paint will serve as a fine vapor barrier.
2. Sealing all air leaks from the heated spaces into cold spaces is extremely important.
3. Deciding whether the mold has progressed enough to require a tear down and treatment.
4. If the cellulose is wet, it does not like to be and will dry very very slowly. I usually recommend it be removed.
5. Until under control, minimize extra moisture inside the house. That is where all of the water you see is coming from.
6. Air seal the door going up to that attic and any plumbing, chimney, or other openings where moist air can flow.
7. A hot roof style of insulating those rafters would eliminate the need for venting and increase the depth of your insulation. Usually done with spray foam so absolutely no air can get past to the cold surfaces, but it can be done with cut and fit rigid foam board sealed in place.

I'll let you chew on that, and don't feel bad about trying to make improvements and moving backwards, this process of insulating and air sealing is far more complex than one would think. In other words, you are not the first.

Bud

 

Thanks Bud, your advice is always appreciated.

We were planning on replacing the shingles this upcoming summer. No leaks, no shingle damage, just close to the end of its life and we were going to be proactive. The sheathing did look good, we weren't planning on replacing it.

That said, this is an old house with iffy horsehair plaster that we have been remodeling a bit at a time. So we were eventually going to gut the upstairs anyways.

So I'm forced with two options.

1. When we do the roof, cough up some extra money to have them scoop out the probably wet blown in insulation....install modern insulation, proper soffit venting, and new sheathing.

2. Or since the sheathing is in good physical shape(aside from the mold), gut the upstairs, remove the existing insulation, KILL THE MOLD, install proper venting and insulation, remodel the upstairs.

Option number two kills two birds with one stone.......its just an EXPENSIVE stone. Its earlier than we had planned on doing this but it had to be done anyway.

Never a dull moment. What confuses me is why this happened now. Why now has warm moist air made its way into the attic were before it didn't? The improvements I've made should have helped prevent this.

 

There are a couple of places where I can guess the moisture may be coming from. Being an old house, is it balloon construction where those wall studs extend all the way to the basement and create an open air path all the way to the rafters? If so, that moist air could still work its way past the cellulose in places and over time cause it to become more compacted and thus increase the air flow. Just guessing, but gravity and time would ultimately pull that cellulose away from the roof deck and create a space for air flow. And given that the only source for air is humid inside air, there is your moisture source.

I doubt if the added insulation created the problem.

Bud

 

Bud, you are right...I do indeed have balloon construction.

The cellulose insulation had settled in the rafters, and I'm guessing it provided enough air flow to prevent mold growth. When I added the cellulose to the low/settled spots and stuffed the rest with R-19, I think I may have decreased airflow to the point were the moist house air had time to "stick".

So in my attempt to tighten things up, I did just that. The problem is that without proper vapor barriers the warm moist air has no way out.

Tonight I am going to check the bathroom fan to make sure it isn't leaking into the attic.

 

One last question. I was discussing our options with my wife and basically told her we were looking at a $15k gut/remodel job for the upstairs.....a few years sooner than we had planned. This is on top of the new roof we were planning on for next year.

She was a bit taken back and doesn't want to believe me, and I guess I can't blame her. We wen't from fine-and-dandy to moldy overnight. She wants me to bring someone in for a professional opinion before we commit to anything.

So who is the right on to call? A mold remediation specialist, a roofer, or a general contracter?

I'm inclined to think the mold guy but they'll probably try and convince us we need knock the house down to the foundation and chemically treat everything.

 

LOL, call a plumber and he will have a plumbing solution, it does work that way. A good building inspector usually doesn't have something to sell you and a good one can cover a lot of issues.

Tell your wife my feelings are hurt, just kidding. But she is correct, more opinions and from people who are there looking at the problem. And you are correct, some will find a problem no matter how hard they have to look, it pays their mortgage.

Short term, get the humidity level down and stop the mold growth. If it isn't too far along, you might be able to clean it up. Then address to big problem when the weather is warmer.

If we back up for a second, the balloon construction that goes all the way to the basement, what's down there. If a dirt floor, they are noted for lots of moisture. Perhaps blocking any air flow up into those spaces could be a solution.

have to run
Bud

 

Do you have a chimney? Any crack in the mortar or chimney lining would certainly let moisture in.

 

i don't want to contradict Bud because he has made alot of good points. However, I do believe the insulation is the problem. if you blew insulation into the rafter space and did not leave any airspace between the insulation and the underside of the roof sheathing then you will move the dew point inside the building and create the very problem you are having. I believe you have to remove the blown in insulation in the rafter space and make sure the insulation in the small triangular attic space is also allowing airspace so the underside of the roof sheathing can vent. In an old house like yours it is very possible that your soffits have enough cracks and creavices to allow for air movement between the soffit and the ridge. if not I would cut some in some to improve airflow. Gable vents would not do much good seeing as they would have to be very close to the top of the roof line anyway (basically in the same location as the ridge vent). The idea is to keep the underside of the roof deck clear to allow air movement and to keep it as cold as possible. Good luck.

 

Hi spiper,
I'm not sure it is the insulation that has created the moisture problem. I suspect something has changed inside. One I missed in my guessing was the new wood burning activity. If any of that wood is being stored inside or even in the basement it can drive the humidity level to dripping.

This is one of the difficult combinations where it is an unheated storage area, yet sealed with no venting. That means it will get colder than the rest of the house and accumulate moisture from the warm humid air below.

The three choices are:
1. Either the moisture level has increased,
2. The temperature level has decreased, or
3. The path for the moisture to escape has been blocked.

Aren't remote audits fun?

Bud

 

Bud/Spiper...thank you for your responses.

Although the wood stove is the only "new" thing in the house...I'm not sure if it or the wood could have caused the problem. Especially considering the bathroom vent is only a couple years old and the house has never seen enough moisture in the attic to cause mold.

In September I did have a cord of seasoned wood in the basement but I have a hard time believing it was the problem. I have a large dehumidifier in the already dry basement and the humidity level has never gotten about 55%. It has been in the 40's for humidity for the past couple of months.

Even now though even after I pulled the fiberglass insulation away from the sheathing and packed down the cellulose to push it away I am still seeing evidence of moisture.

When this thread first started I sprayed bleach all over the sheathing to kill the mold. It did so but the moisture remains. I have pine planking on the roof rafters. The last time someone did the roof they installed plywood over the planking. On cold nights I see frost on the plywood in between the pine planks.

Removing the insulation and installing rafter vents is virtually impossible from the attic. This summer I am going to gut the bathroom and 3rd bedroom. At that time I'll install R19 and proper soffit/rafter venting. This will properly vent about 50% of the North side and 1/3rd of the south side.

Also, since there is no vapor barrier under the blown in insulation I am going to paint all of the upstairs ceilings with vapor barrier paint which will hopefully slow down some moisture intrusion.

Thanks again!