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Unvented Attic Building Science & ActivePure® Defense

Spray Foam Attic Moisture & Depressurization Simulator

Simulate how unvented spray foam attics in Florida trap moisture vapor, trigger roof deck wood rot, pull chemical VOC off-gassing into bedrooms, and how the Sani Home Protected Ecosystem (Dehumidification + Sani Attic Guardian) guarantees a safe building envelope.

Florida Building Science Tool

Spray Foam Attic Moisture & Depressurization Risk Simulator

Simulate how unvented spray foam attics in Florida trap moisture, create structural depressurization, off-gas VOCs, and how the Sani Home Protected Ecosystem eliminates contamination risks.

SAFE ATTIC ENVELOPE
1-Click Simulation Scenarios:

Attic & HVAC Parameters

Unvented spray foam moves the thermal boundary to the roof deck, sealing all natural soffit and ridge vents.
1,800 sq ft
800 sq ft 2,400 sq ft 4,000 sq ft
Leaky ducts in an unvented attic create severe depressurization, pulling attic air into living rooms.
Maintains attic relative humidity below 50% RH to prevent wood activity ($a_w$).
Actively destroys VOCs, fish smells (off-gassing), and neutralizes fungal DNA in the attic envelope.

Real-Time Risk Analysis Live Update

Roof Sheathing Water Activity
0.48 aw
Safe Range (< 0.65)
Attic Depressurization Pull
12 CFM
Negligible Leakage
VOC & Odor Neutralization
99.4%
ActivePure Active
Fungal Germination Window
No Risk
Spores Inactive
Attic Envelope Airflow & Contaminant Vectors Envelope Balance: Stable
SEALED ATTIC CAVITY Attic: 78°F | 46% RH DEHUM ATTIC G Depressurization Suction LIVING SPACE (Clean & Balanced)
Sani Home Protected Ecosystem Active

Your attic humidity is locked under 50% RH by the dedicated dehumidifier, while the Sani Attic Guardian neutralizes insulation off-gassing and mold spores 24/7.

100% Protection Coverage
Request Free Spray Foam Attic & Moisture Audit
Florida Building Science & Hygrothermal Analysis

The 3 Hidden Risks in Sealed Spray Foam Attics

Based on research from Building Science Corporation (Dr. Joe Lstiburek), ASHRAE 160, and Florida climate psychrometrics.

1. Roof Deck Moisture Trapping

Sealing soffits and ridge vents prevents natural airflow. Moisture vapor from living spaces migrates into the unvented attic. Without dedicated mechanical dehumidification, humidity rises above 70% RH, elevating roof sheathing water activity (aw ≥ 0.70) and rotting roof wood underneath the shingles.

2. Attic Depressurization Pull

Air handlers placed in unvented attics create pressure imbalances during operation. Duct leaks or supply/return imbalances depressurize the sealed attic cavity, sucking attic air, insulation dust, and trapped odor compounds down into bedrooms through ceiling penetrations.

3. VOC Off-Gassing & Fish Odors

Improperly mixed chemical spray foam or high attic heat causes off-gassing of volatile organic compounds (VOCs / mVOCs) producing unpleasant "fishy" or chemical smells. The Sani Attic Guardian (ActivePure®) actively neutralizes these compounds 24/7.

Spray Foam Attic Protection Matrix

Attic Assembly Condition Attic Humidity (% RH) Roof Sheathing (aw) Depressurization Risk VOC / Odor Level Ecosystem Protection Status
Uncontrolled Spray Foam (No Dehum/No Guardian) 72% - 85% RH 0.75 - 0.88 aw High Suction into Rooms High Off-Gassing Trapped 🚨 CRITICAL ATTIC FAILURE
Dehumidifier Only Installed 45% - 48% RH 0.46 aw (Safe) Moderate Leakage Pull Moderate VOCs Trapped 🟡 Partial Protection (Humidity Controlled)
Attic Guardian Only Installed 68% - 78% RH 0.70 aw (Elevated) Moderate Suction 99.4% VOC Neutralized 🟡 Partial Protection (Pathogens Neutralized)
Sani Home Protected Ecosystem (Both Installed) < 48% RH 0.45 aw (Optimal) Balanced Pressure 99.4% VOC Neutralized 🛡️ 100% FULL ECOSYSTEM DEFENSE

Frequently Asked Questions about Spray Foam Attics

Spray foam insulation moves the thermal envelope to the roofline, sealing soffit, ridge, and gable vents. Without dedicated dehumidification, moisture vapor entering the unvented attic becomes trapped, elevating water activity (aw ≥ 0.70) and causing structural wood rot in roof sheathing.

As the air handler operates in an unvented attic, any small duct leakage or thermal expansion depressurizes the attic cavity. This creates a vacuum effect that pulls unconditioned attic air—containing VOC off-gassing, insulation odors, and mold spores—down into the living spaces.

The Sani Home Protected Ecosystem pairs a Dedicated Attic Dehumidifier (which locks relative humidity below 50% RH) with the Sani Attic Guardian powered by ActivePure® Technology. The Attic Guardian actively destroys VOCs, fish smells, and fungal DNA 24/7 in the sealed attic envelope before air enters living spaces.

Open-cell spray foam is vapor permeable, allowing water vapor to migrate through to the roof deck where it can condense if unmanaged. Closed-cell spray foam forms a rigid vapor barrier, but still requires strict attic humidity control to protect exposed wood rafters and HVAC equipment.

Concerned About Your Spray Foam Attic Moisture?

Our building science specialists evaluate spray foam attics using thermal imaging, pinless moisture meters, and pressure diagnostics to protect your roof and indoor air.

Book Your Free Spray Foam & Attic Moisture Audit
772.206.2121

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