Ventilation and Condensation

What is Ventilation?

  • Process of supplying a continuous supply of air through the attic space.
  • 50% intake/ 50% exhaust.
  • Exhaust should be at 3 feet higher than the intake system
  • Intake should be under the eave
  • Exhaust should be close to the peak

The main goal of the ventilation process it to have Good Air In, Bad Air Out! Fresh air comes in through the intake vents. Heat and Moisture are released through exhaust vents in the attic.

Why Should you Ventilate?

HEAT and MOISTURE are the enemies in your home and are present geographical all year round


  • Attics can reach 140 to 150 degrees if Unventilated
  • Heat can cause damages to shingles, roof sheathing, and radiates into living area


  • Moisture enemy # 1
  • Causes mildew, mold, rotting, paint blisters, and ineffective insulation


  • Result in “sick attics” – Toxic mold and mildew


  • Attics, crawl spaces, and basements are prime sources for excess moisture.
  • Spores need a food source, heat and moisture, to begin colonizing.
  • Usually improper intake is the culprit in moisture related problems in attics.
  • Extreme caution should be exercised if an odor or colony is detected.

Remember when installing kitchen and bathroom fans; DON’T vent them into the attic space. These heat and moisture sources must be ventilated outside.

Learn more about Ventilation and Condensation in this detailed document by Lomanco Vents.