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Humidity: The Silent Killer of Good Builds | Build Show Podcast Ep. 237

📅 November 1, 2026 ⏱️ 47:42 🎤 Matt Risinger, Nikki Krieger

Chapters

Click to jump to section

  • 0:00
    Humidity: Silent Killer
    Introduction to the topic of humidity and its impact on good and bad builds, targeting both builders and homeowners.
  • 0:36
    Guest Introduction: Nikki Krieger
    Matt introduces Nikki Krieger, a long-time friend and expert from Santa Fe, Ultra-Air, and Aprilaire, discussing their history together.
  • 1:21
    Dehumidifier vs. AC
    Nikki explains the fundamental differences between how a dehumidifier and an air conditioner operate to remove moisture.
  • 1:35
    Oversized AC Problems
    Discussion on why oversized air conditioning systems and short cycling lead to poor dehumidification and potential house issues.
  • 2:35
    Humidity, Dew Point & Mold
    Exploration of the relationship between relative humidity, dew point, and mold growth, with recommended indoor targets.
  • 3:09
    Tight vs. Leaky Houses
    How moisture control differs in tight, well-built homes versus leaky homes, emphasizing control opportunities in tight builds.
  • 4:00
    Dehumidifier Types & Placement
    Guidance on choosing between portable, whole-house, and ventilating dehumidifiers, and where to start in different home scenarios.
  • 4:44
    Matt's Dehumidifier Philosophy
    Matt shares his preference for separate HVAC, dehumidification, and ERV systems, and the benefits of CO2 monitoring.
  • 5:39
    Dehumidifier Sizing Explained
    Nikki clarifies how dehumidifier pint ratings are calculated and how ambient conditions affect actual performance and capacity.
  • 6:58
    Dehumidifiers in Bad Builds
    Discussing the limitations of dehumidifiers in poorly constructed or leaky homes, stressing the need for air sealing first.

Speakers

M
Matt Risinger
Host
N
Nikki Krieger

Key Takeaways

✦

Size AC systems correctly using Manual J calculations to ensure longer run times (at least 30 minutes) for effective dehumidification, avoiding short cycling that re-humidifies interior air.

✦

Aim for indoor relative humidity between 45-55% and a dew point below 55°F to prevent mold growth and material moisture absorption.

✦

Implement dedicated dehumidification systems (separate from HVAC) especially during milder seasons when AC systems run less frequently and cannot adequately remove moisture.

✦

Prioritize dehumidification in crawl spaces and basements first, as up to 50% of air from these areas can enter the living space.

✦

Consider installing multiple dehumidifiers in multi-story or complex homes (e.g., one upstairs, one downstairs) for better zonal control and redundancy.

✦

Over-size dehumidifiers slightly beyond calculated needs to account for variable occupancy, lifestyle changes, and seasonal fluctuations in moisture generation.

✦

For leaky homes (e.g., above 5-7 ACH50), a dehumidifier alone is insufficient; prioritize air sealing to reduce infiltration before relying solely on mechanical dehumidification.

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