I believe I discovered mold on the underside of my roof decking... and a lot of it. The boards down at the eaves are gray in color (as opposed to the yellow pine of the rest of the roof lumber), and as you move up four feet from the eaves or so, the discoloration becomes patchy dots and splotches that look like mold colonies to me.

It spreads over maybe 30sq ft of decking.

I don't know if it's cosmetic mold that originally was part of the frame or if it's active black mold like Stachybotrys.

I'm mad that the inspector didn't point it out to me. In fact I don't think he ever even looked up during the inspection of the crawlspace, and at that time I knew nothing about what to look for.

My research is suggesting that having the mold removed is pretty much useless unless the source of the problem is identified and fixed. Does this essentially mean I need to hire two companies - one to remove the mold and another to inspect the roof moisture and air flow setup? I can't seem to find any mold remediation companies that also do the longer term structural fixes that might be needed.

This problem has me a little concerned. Any advice you guys have would be very welcome!

~C
1955 1.5 storey Cape Cod, Milwaukee, WI.

 

That kind of sounds like a big enough issue that you might not want to tackle it yourself. Mold remediation isn't an easy task when you're dealing with the amount you're describing. I would guess that the company that removes it, might have some contacts who would do the preventative part of things.

 

Thanks Bill, yeah that's what I was thinking. I guess the other route would be to have a pro remove what mold is up there then get in there myself to make sure the ventilation is all correct. Unfortunately the old insulation is such a mess up there I'd probably have to vac it all out before I could even see the eave vents. I have a feeling that the old owner was a DIYer who didn't really know or care about attic airflow.

Can anyone give advice on what I should be on the lookout for when hiring a mold remediation company? Is there a particular licensing I should require etc.?

 

Hi cg,
The wood turning black or dark is common and although a sign of some sort of mold, I would address the moisture source and ventilation first. This is just an opinion from a non-expert in the mold field.

For mold to form it needs food and moisture. Wood is the food, hard to eliminate that, but air leakage from the inside is probably the moisture source. If there are soffit and high vents then a small amount of moisture should have been vented out. Since it is predominately down low, it sounds like the venting is not working.

Describe your vents. Capes will often have soffit and gable vents, but the lower soffit may dominate the function of the higher soffit. let's hear what is there before I speculate.

Bud

 

I think the warm air from the floor below, and cold air from this room/area is potentially creating your condensation, which is a good source for your mold.

 

Mike, if that's the case how would I go about fixing it? Is it a case of correctly insulating the cathedral ceiling slopes or are we talking putting insulation between the two floors, or having heating ducts run up to the second floor? I hear that last one is very expensive?

 

I'd correct the insulation/ventilation in the affected areas. From there, if you are going to make this a warm area, add heat (electric baseboard heater of HVAC duct). If you are going to keep it unheated, you'll need to seporate the floor below from this unheated area with a door of some sort.

 

Thanks for the advice! Putting a door on the bottom of the stairs won't be too much of a problem.

Could correcting the insulation be as simple as clearing the soffit vents and adding more batting? Or would I be looking at a full demo, tearing down the plaster and lathe, and insulating between the rafters all the way up to the ridge then re-drywalling? Maybe there's an option inbetween the two extremes that I'm not aware of?

 

So I finally had some daylight time to check out the ventilation situation from the exterior.

The house is about 30x30' and there are small square vents at each gable and three small soffit vents under the eaves about 10 feet apart each. I don't see a ridge vent but on one slope of the roof only, there are three square metal static vents.

My new question is, is that adequate ventilation for the house or would I be better off getting up there in the spring and installing continuous soffit vents and a ridge vent?

Thanks all sincerely for your help!

 

The most often quoted guideline for vent area would be 1 ft² of vent area for every 150 ft² of attic floor. The details:

1. Vent area needs to be split half high and half low.
2. The area you use is not the area of the vent, but its NFA (net free area). A 12" x 12" vent might be 1 ft² in area, but might have only 0.5 ft² in NFA.
3. It sounds like you are way short on low vent area. That might explain the problem being in the lower area.
4. When the ceiling below the attic is properly air sealed and well insulated, the venting requirements shrink considerable, plus you reduce the heat loss. But moisture is your current issue and that definitely needs air sealing and then ventilation to carry away what you can't keep out.

Bud

 

Yes, in addition to air sealing and installing the proper level of insulation on all faces of your conditioned space.

I may have missed this: Do you have an unfinished attic or rooms up there?

 

It's a finished room, plaster and lathe, with kneewalls.

 

The best way to stop the draft coming down the stairs would probably be to insulate that room to be part of the conditioned space. R-38 or better above any flat ceiling, all you can get above the sloped areas while still allowing for air flow for ventilation, R-13 or better in the kneewalls. You can get the optimum values by entering the information for your house into the ZIP-Code Insulation Program. Add the ceiling insulation into the first floor ceiling between the kneewalls and the eaves too.

While it will never be as warm in the winter nor as cool in the summer as your main floor, unless you add ducting or some other HVAC improvement, it should stop being such a major contributor to main floor discomfort.