Control moisture with three moves: Ventilate smartly—aim for 0.35 ACH or 15 cfm per person, run kitchen/bath/laundry exhaust during and after use, and keep CO2 around 850–1200 ppm. Dehumidify wisely—use portable units in damp rooms, match capacity to space, maintain your AC, and track RH to stay between 40–60%. Seal the envelope—air-seal seams and penetrations, use proper vapor retarders, and add continuous insulation to prevent condensation. There’s more you can do to keep humidity steady year-round.
Optimize Ventilation and Airflow
Even in a well-sealed home, moisture builds up fast unless you move air deliberately.
Start by targeting 0.35 air changes per hour or at least 15 cfm per person. Manufactured homes often have lower natural ventilation, so you’ll need mechanical ventilation to keep humidity in check. Mold thrives in moisture-rich environments, so it’s essential to manage indoor humidity effectively.
Target 0.35 ACH or 15 cfm per person—manufactured homes need mechanical ventilation to control humidity.
Run exhaust in kitchens, baths, and laundry rooms during and after use. Combine natural ventilation with balanced systems to maintain CO2 near 850–1200 ppm and indirectly slow moisture buildup.
Use smart controls to time-shift airflow when outdoor air is cooler and drier, reducing hours above 60% RH without big energy penalties.
Design ducts to deliver 150–300 cfm for ERVs. Schedule multi-hour night ventilation for free cooling.
Keep indoor RH between 40–60% across seasons. To maintain healthy air, consider a dedicated whole-home humidifier or dehumidifier that automatically adjusts to keep humidity within the recommended 40–60% range.
Deploy the Right Dehumidification Strategy
While ventilation slows moisture buildup, you still need targeted dehumidification to keep indoor RH in the 40–60% range.
Start by placing portable units in basements, bathrooms, or laundry rooms, and match dehumidifier capacity to room size and humidity—bigger, wetter spaces need higher pints-per-day. Running your AC also helps because AC systems remove moisture as they cool the air. Regular sump pump maintenance is also crucial to prevent excess moisture in basements.
Keep doors and windows closed when running units, empty tanks, and clean filters to sustain performance and prevent mold.
For whole-home control, consider a professionally installed system integrated with your HVAC.
Verify your AC is properly sized and maintained; oversized systems short-cycle and remove less moisture.
In humid climates or with mini-splits, supplement cooling with dedicated dehumidifiers.
Run AC during humid periods when outdoor temps allow.
Use hygrometers to track RH and adjust settings.
Add moisture absorption options—rock salt, baking soda, or calcium chloride—for closets and small spaces.
Fortify the Building Envelope and Moisture Barriers
Because moisture moves with both air and vapor, you need a tight, well-detailed envelope that blocks bulk water, controls airflow, and manages vapor.
Start with continuous air barriers: seal sheathing seams, plates, and penetrations; integrate them with WRB and flashing. Choose vapor retarders by climate—low perms in cold zones, higher perms or smart options in mixed climates—and place them to avoid condensation at cool interfaces. Don’t stack multiple vapor retarders in one assembly. In hot, humid climates, coordinate envelope details with HVAC to maintain positive pressurization and limit moist air infiltration. Effective basement waterproofing can further enhance moisture control by preventing water intrusion.
Design a robust drainage plane: high-drainage WRB behind cladding, kick-out flashing at roof-to-wall intersections, and properly lapped flashing at windows, doors, and vents.
Add continuous insulation to warm interior surfaces and cut condensation risk. Use closed-cell insulation strategically, and install vapor control layers under slabs or crawlspaces to block ground moisture.