Attic heat loss diagnostic
Attic Mold or Black Staining
What you see outside often starts inside the attic.
The short answer
Dark staining on attic sheathing or rafters usually means that surface has been repeatedly wet. The moisture comes from warm indoor air condensing, from a fan discharging into the attic, or from a roof leak. Treating the staining without correcting the source is why attic mold comes back, so the source is part of the work, not an extra.
Heat leaves through five places.We check every one.
A cold room is the end of a path, not the start of one. The envelope has four weak points, and which one matters is decided in your attic, not on this page.
- 1The roof deckAttic inspection, moisture reading of the sheathing
- 2Above the bathroomTrace the duct to its termination
- 3The sheathingLook on a cold morning, before the attic warms up
- 4A roof penetrationInspection at the penetration after rain
- 5Soffit intakeSoffit and baffle inspection
Reading the evidence
A visible symptom narrows the cause. It does not settle it on its own, which is what the quote on your own attic is for.
Black staining on the underside of the roof deck
Likely causeRepeated condensation on a cold surface
How we confirm itAttic inspection, moisture reading of the sheathing
If confirmedMold remediation with air sealing
Staining concentrated near a bathroom
Likely causeA fan discharging into the attic
How we confirm itTrace the duct to its termination
If confirmedDuct correction, then remediation
Frost or beads of water on the nails and the deck, with no staining yet
Likely causeCondensation on cold surfaces, which precedes staining rather than being it
How we confirm itLook on a cold morning, before the attic warms up
If confirmedTreat it as condensation, not as mold
Staining in one small area under a roof penetration
Likely causeA roof leak rather than condensation
How we confirm itInspection at the penetration after rain
If confirmedRoof repair first, then remediation
Staining across the whole attic with blocked soffits
Likely causeNo intake air, so the attic never dries
How we confirm itSoffit and baffle inspection
If confirmedVentilation correction with remediation
What this page cannot tell you
- This page describes conditions in a building. It does not make health claims, and it is not a medical assessment.
- Visual staining is not a species identification. If testing matters for your situation, that is a separate specialized service.
The recommendation hierarchy
The source is identified and corrected as part of the remediation. Cleaning a stain without stopping the moisture is temporary by definition.
Primary solution
Mold Remediation
Professional mold remediation for attics, basements, walls, ceilings and other affected residential areas.
Explore this service
Conditional solution
Attic Ventilation & Airflow
Use it: if moisture is not being exhausted from the attic.
About this problem
Questions homeowners ask us.
Everything below is about attic mold or black staining. Tap one.
Eco-Therma
Usually replies the same day
Can attic mold be cleaned without fixing anything else?
Attic mold can be cleaned, but if the moisture source is still there it will return. That is why Eco-Therma treats the source as part of the work rather than as a separate recommendation.
How do you tell condensation from a roof leak?
Condensation tends to be widespread and follows cold surfaces and nails. A leak is usually localized around a penetration or a valley, and it changes with rain rather than with cold.
Do you have to remove the insulation?
Only if it has been wet or contaminated. Eco-Therma leaves insulation that is dry and in good condition in place.
A practical next step
Request a Remote Quote
A remote quote starts and finishes with your address and the approximate size of your attic. No attic access, no waiting on a visit.