Replace roof or remove attic mold?

We moved into our house about five years ago and did not notice the attic mold. Shame on us. Our attic has mold on all for sides of the hip roof. The worst of course is on the north side of the attic. I would guess mold covers 60% of the attic sheathing. However, no mold has grown on the supporting joists that are in contact with the sheathing. Since I was not the original owner, I can only guess what caused the mold. We know the previous owners overhauled both upstairs bathrooms and properly vented the shower/bathroom fans with PVC running through the attic and to the outside of the roof. The problem is, it’s quite possible that for many years prior, the bathrooms either had no fans to remove moisture, or they did, but they may have been vented to the attic. Clearly, moisture has made it into the attic and caused lots of mold.

Our roof has a power ventilated fan in the upper center. It also has three plastic roof vents near the top of the roof. All vents on are the west side of the roof. The soffits have a total twelve vents to supplying air into the attic and exiting through power vent/plastic vents. The attic floor is about 800 sq. ft. and this is a two story house. I believe the power ventilated fan was installed after the house was built.

I believe the source of moisture has been solved with the proper venting of the showers, but I’m not 100% sure. My attic floor has no vapor barrier, but has about 8 inches of blown-in insulation on avg. Was it unusual to have a home built without a vapor barrier during the 80’s? I have no clue why anyone would do that. I suppose moisture could be making it’s way through the attic floor. Since I have noticed the mold (about four years ago) I have installed a humidistat on the power attic vent so I can run the fan in the winter as well. It appears the mold growth has slowed or stopped, but it’s still there.

My house was built in 1982 and most likely has the original roof. While the shingles still have some life in them, I will need a new roof soon. Does it make more sense to just have the singles and roof sheathing replaced instead of having the mold professionally removed? I’m not sure how much added cost the sheathing replacement would entail, but the remaining mold would definitely be gone if I went this route. My concern is it could return. I suppose I could just keep checking the new roof sheathing to see if mold reappears. If I caught it early this time, I could have a mold remediation company solve the problem and it wouldn’t be too costly

I live in Northern Illinois.

Thanks in advance for your feedback.

I should add that I made sure the soffit vents are drawing air and no insulation is getting in the way.

Your roof top mushroom vents are short-circuiting the proper path of ventilation flowage. When the PAV kicks on, it will draw air from the path of least resistance, thereby the mushroom vent are now acting as intake vents rather than the soffit vents.

You do not have enough soffit ventilation at all. The current reccomendation is to have 100% of the soffit panels being vented, if that is the intake system chosen.

Is your family affected by any allergies, which are now being magnified by the presence of old stagnated mold growth? Only a small 10 square foot area is all that is recommended by the EPA to be cleaned. If the mold growth is larger than 10 square feet, then the EPA recommends either a mold remediation company for cleaning or to remove the organic products that it is attached to.

A vapor barrier only inhibits 2% of the moisture permeation. 98% of vapor transmission, not counting actual incorrect exhaust dumping into the attic, are from the unsealed wall plates and other penetrations in the buiding envelope.

Where in Northern Ilinois are you located. I am near the Elgin area and could recommend someone in your area to you.


Right Way Roofing Company
(847) 426-9730

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I live in Glen Ellyn. If that’s the case on the vapor barrier, then proper ventilation is really the key to eliminating attic moisture. It sounds like either way, I still need to have some attic ventilation work performed. Maybe I should just go with the new roof (including sheathing) so the roofer can properly address the ventilation at the same time.

I go to Villa Park Harley once in a while, now called Wild Fire Harley.

Your assumption would be correct about the ventilation being a priority.

Depending on the structural integrity of the existing deck sheathing, removal and replacement of all of the sheathing would still be a possibility. If the mold spores are not in an active stage of growth, they will do no additional harm, yet they stil are a harmfull matter to have inhabiting your homes environment.

The “Jury” is still out on the effects of mold and their are many companies taking advantage of the most extreme cases to exagerrate the potential adverse affects. With that being said, it still is no laughing matter.

The best way to remediate the existing intake ventilation, since you are planning on a new roof, would be to install a shingle over style intake ventilation product, such as Smart Vent, made by DCI Procucts, Inc.

Intake ventiation accounts for 60% of the entire ventilation system and is more usefull than the roof top exhaust vents, but both are needed for a properly functioning and balanced system.


Provide me with type of insulation
Density of insulation
Need to know upper attic if any potlight, also picture of your attic bathroom exhaust connection.
Picture of the attic perimeter
Picture of your soffit (Overhang)
Need to know if you got any knee wall or skylight shaft
An picture of the mold under the plywood
If possible inside attic temperature versus outside
Age of the house and the roof
And on a scale of 1 to 100 % how would you rate your house about being air tight.
With that I should be able to give you all info you need.
But hurry up… leaving for Cuba this monday and after I’ll be overloaded with work
So I won’t have time to come here very often

I had a local roofer check the house over the weekend. As it turns out, the bathroom exhaust vans are not vented properly. In fact, they are not vented at all. They blow the hot, moist shower air into the attic! I thought it was vented properly because I saw PVC pipe in the attic. Turns out that was the plumbing stack. I’m no expert on roofing. However, I do have enough common sense to understand why it’s a terrible idea to vent your bathroom exhaust vans directly into the attic. Someone was either lazy or didn’t know better. It seems pretty easy to understand the purpose of the bathroom fan is to remove moisture. The purpose is not to route moisture into the attic.

OK, I’m done ranting. After speaking with the roofer, I decided it’s best to start over and have all the plywood sheathing removed. I have a quote from the roofer. It seems fair, but I would like to get at least one more quote from another roofer.

My roofer suggested installing a ridge vent on the peak. I like the idea and agree with him, but he said I would still want to run my power attic vent for added static venting. I was really hoping I could do away with the power vent by installing the ridge vent. Does this seem like overkill? Won’t the power vent draw turn the ridge vent into an intake?

Oh man, I was just starting to like your roofers diagnosis, until I got to your point about having both, the PAV plus the ridge vent.

You are correct. The Powered Attic Vent would draw air in through the path of least resistance, which would be the ridge vent.

Now, consider if you have the type of PAV that not only has a thermostat but also a humidistat to relieve the attic from not only the excessive heat, but also the internal Relative Humidity content. Now add either an outside rain or a fresh powdery snow to the mix. Boom, outside weather going into the attic.

Also, the ONLY type of ridge vent that should be used, is either the Shingle Vent II or the Snow Country product, where each of them contain an external wind deflecting baffle which creates additional draw out of the ridge vent louvered slots.

Good luck if you choose this guy. A good price is one that does the proper job using the correct technology and actually utilizes it during their everyday instalations.

Everybody can claim that they are doing their job the Right Way, but it is far and few that actualy do.

I hope this was some help to you. If you need more, please feel free to ask as much as possible.


Ed you seem very knowledgeable about all this stuff!

My husband and I are very excited to purchase our first home in Lisle, IL.

Last night, the inspector found mold in the attic and said it needs to be remediated. He recommended having a professional come out.

Since it’s in the attic do I have a roof company come out? Based on what I’ve read it said attic mold is mostly due to poor ventilation… Should I have a ventilation professional come out first?

Any info would be great!