💧 The dew point in the attic

The dew point in your attic changes based on 2 factors.

  • Temperature and humidity

Why it matters: Knowing the dew point will help you understand when water will become a problem in the attic.

🧮 By the numbers: Right now, the temperature in my attic is 81 degrees and the relative humidity (RH) is 59%.

🤔 What does it mean?

  • The dew point tells you the SURFACE TEMPERATURE where water will condense out of the air.
  • Any part of my ductwork that’s metal and not well insulated can easily get to 65 degrees —> the cold air flowing through it is 55 degrees.
  • The copper line carrying cold refrigerant through the attic to the air handler is cooler than 65 degrees as well.

🥊 The bottom line: Any surface in your attic that reaches the dew point will condense water.

  • That water will drip from the surface onto insulation, your ceiling, etc.

✅ For your Smart Homeowner list

  • This is one example of how water can be a problem in hidden spaces in your home — which includes the attic, crawl space and even inside walls.
  • And it’s why air sealing and insulating are the best ways to keep water out.



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