Attic Mold - Treatment & Removal

Why Attic Treatments Fail

The problem is revealed even before we talk about the types of treatments available.  It’s in the name itself.  By referring to the task of mold remediation as a ‘treatment’ it implies that the solution lies in some sort of chemical or coating.   Treatments make sense in many situations.  If you’re building a deck, pressure treated wood will greatly increase the life of your lumber.  If you have an insect problem, spraying a bug treatment around your property is a sensible technique for keeping the pests away.

You would not, however, treat a leaky pipe or a flooded basement.   You would fix/ repair/ remediate/ the water intrusion problem.   Yet when you step into the unscrupulous mold remediation industry, something strange occurs.  Many contractors are perfectly happy to sell a treatment without fixing the underlying problem.  All too often this succeeds.  Why?  Most homeowners have never dealt with a mold issue and have a difficult time parsing out the scam from the solution.

The motivation to forego fixing the underlying problem is understandable.  Fixing the cause of attic mold growth can be hard.  Crawling around the entire attic counting can lights and collecting measurements is fairly unpleasant.  Popping your head up in the attic for 2 minutes and performing your inspection from the hatch is a tempting alternative.

But of course, this is worthless.   This is akin to hiring a plumber who, after finding a leaky drain pipe, doesn’t bother fixing the broken pipe and instead tries to sell you a dehumidifier.  If this sounds absurd, you’re right.   Yet, this is how 90% of attic mold projects are handled.

The attic in the image above was treated only 4 months before this photo was taken.  You’ll notice the mold growth is unimpeded by the ‘mold treatment’.  Why is this?  Unfortunately, all treatments run about against a cold, wet, unyielding fact: Within a few months a layer of dust settles on the treated surfaces (even inverted surfaces).  This dust contains a lot of organic material.  Mold eats organic materials.  So, while the coating is proudly protecting the the sheathing beneath it, the mold is happily growing on the dust.  Now, this is not entirely true.  In time, the coating will fail and the mold will extend its growth into the sheathing.

How can you tell if you’re dealing with a  bid?

Look for exclusions in the warranty

THE RIGHT WAY TO TREAT ATTIC MOLD   

Identify the moisture problem

Now the hard part begins.  It’s easy enough to shoot holes in the treatment only techniques.  It’s quite another task to successfully identify the cause of attic mold growth in each unique situation.  The cause of the excess moisture must be clearly identified.  In most cases, this is due to several compounding factors.

Poorly connected exhaust fan

Rule out roof leaks

Condensation often masquerades as a roof leak.  The image below is showing the conjunction of the skylight and the roof.  This is a common place for roof leaks. It’s also a common location for condensation problems.   During showering, a bathroom is inundated with tremendous amounts of humidity.   If the exhaust fan isn’t working well or the skylights are set in a deep channel in the ceiling, the warm moist air will become trapped in this area.  Unless it’s well sealed, the moisture will quickly move into the attic space where it will hit the cool surface of the roof sheathing.

Stop Air Infiltration

Attic mold remediation should include techniques to limit the amount of air movement from the occupied portion of the house into the attic.   Much of the condensation that leads to mold growth in an attic is due to moist air move up through the ceiling.  The discoloration on the insulation in the photo below shows this air movement.

Mold caused by lack of air sealing

Can lights can be a major source of air infiltration in the attic.  This is especially true with older can lights without an “AT” rating.  Notice the discoloration of the insulation around the can light.  This is due to the leakage of warm, moist air through the gaps within and around the can light assembly.

Dry out the roof sheathing & rafters

If the mold remediation occurs during the winter months, dry out of the attic sheathing is often necessary.  This can be accomplished either through the natural moisture loss that will occur due to the increased ventilation, or through active dry out with heaters, dehumidifiers, etc.  We prefer to let an attic dry out naturally, as this provides strong evidence of the effectiveness of the ventilation improvements.

During extremely cold weather, the moisture on the sheathing may even freeze, leading to a white, frosty coating.  If the condensation is heavy, dripping from the sheathing will begin to occur.  This can look very similar to a roof leak and often leads to a misdiagnosis.

Water droplets on attic / roof sheathing due to condensation

Severe condensation leading to dripping on rafters

Remediate the existing mold growth

After the first two steps are addressed, the mold growth itself is addressed (although sometimes this step is addressed before/during the dry out period).

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