**Denver Drywall: Altitude AC Hiding Toxic Mold?**

By Franklin Everett Shaw

November 5, 2025

The musty smell hits you first, a damp, earthy odor that shouldn’t be there. You dismiss it, blaming the recent Denver rain. But then you notice the faint discoloration on the wall near the baseboard, a subtle pattern that wasn’t there last week. Living in Denver, you know moisture is the enemy, especially when trapped behind drywall at 5,280 feet. This isn’t just a cosmetic issue; it could be toxic mold, thriving in the cool, dark spaces created by your air conditioning.

Denver’s unique climate presents a perfect storm for mold growth, especially behind drywall. The combination of high altitude, which can lead to increased condensation, and the widespread use of air conditioning during the summer months creates an environment where mold can flourish, often undetected until it becomes a serious problem. Ignoring the early signs can lead to costly remediation and potential health issues.

So, how do you know if you have mold lurking behind your walls, and what can you do about it? Let’s dive in.

First, understand the Denver-specific challenges. Altitude affects air pressure, which in turn impacts how moisture behaves. Air conditioners, while providing relief from the summer heat, can exacerbate the problem. The rapid cooling creates condensation, especially on poorly insulated walls. This condensation seeps into the drywall, providing the perfect breeding ground for mold.

DIY testing can be a good first step, but it’s crucial to understand its limitations.

• Visual Inspection: Look for discoloration, water stains, or bubbling paint on walls and ceilings, especially in bathrooms, kitchens, and basements. Pay close attention to areas around windows and pipes.
• Smell Test: A musty or earthy odor is a strong indicator of mold, even if you can’t see it.
• Moisture Meter: A moisture meter can help you detect elevated moisture levels in drywall. You can purchase these at most hardware stores for around $30-$50. Aim for readings below 16% in drywall. Anything higher warrants further investigation.
• Surface Mold Test Kits: These kits, available at home improvement stores, allow you to collect a sample of surface mold and send it to a lab for analysis. However, they only test for surface mold and won’t detect hidden mold behind drywall.

However, DIY tests are often unreliable and can provide false negatives. They also don’t identify the type of mold, which is crucial for determining the appropriate remediation strategy. For example, Stachybotrys chartarum (black mold) requires a different approach than common mildew.

When DIY isn’t enough, it’s time to call in the professionals. Denver has several reputable mold remediation companies. Look for companies that are certified by organizations like the IICRC (Institute of Inspection Cleaning and Restoration Certification) or the ACAC (American Council for Accredited Certification).

Here’s what a professional mold inspection typically involves:

• Comprehensive Visual Inspection: A thorough examination of your home, including hard-to-reach areas like attics and crawl spaces.
• Moisture Mapping: Using specialized equipment to identify areas of elevated moisture.
• Air Sampling: Collecting air samples to determine the concentration and type of mold spores present in the air. This is crucial for identifying hidden mold.
• Surface Sampling: Collecting samples from surfaces to identify the type of mold present.
• Detailed Report: A comprehensive report outlining the findings of the inspection, including the type of mold identified, the extent of the contamination, and recommendations for remediation.

Mold remediation is not a DIY project. Improper removal can release mold spores into the air, worsening the problem and potentially causing health issues. Professional remediation involves:

• Containment: Sealing off the affected area to prevent the spread of mold spores.
• Removal: Physically removing the mold-contaminated materials, such as drywall, carpet, and insulation.
• Cleaning: Cleaning and disinfecting the affected area with antimicrobial solutions.
• Drying: Thoroughly drying the area to prevent future mold growth.
• Source Identification and Repair: Identifying and addressing the source of the moisture problem to prevent recurrence. This might involve repairing leaks, improving ventilation, or upgrading insulation.

A common mistake Denver homeowners make is simply bleaching the visible mold. Bleach only kills surface mold and doesn’t address the underlying moisture problem. The mold will likely return.

Preventing mold growth in the first place is the best strategy. Given Denver’s climate and the use of air conditioning, here are some specific steps you can take:

• Control Humidity: Use dehumidifiers, especially in basements and other areas prone to moisture. Aim for a humidity level between 30% and 50%.
• Improve Ventilation: Ensure adequate ventilation in bathrooms and kitchens by using exhaust fans. Open windows when possible to allow fresh air to circulate.
• Proper Insulation: Ensure your home is properly insulated to prevent condensation. Pay special attention to walls and ceilings that are exposed to cold air from air conditioning.
• Regular AC Maintenance: Regularly clean or replace your air conditioner’s filters. Inspect the condensate drain line for clogs and ensure it’s draining properly. Consider having your AC system professionally inspected and cleaned annually.
• Address Leaks Promptly: Repair any leaks in your roof, plumbing, or windows immediately. Even small leaks can lead to significant mold growth.
• Monitor for Condensation: Pay attention to areas where condensation is likely to occur, such as windowsills and cold walls. Wipe up any condensation promptly.
• Consider a Whole-House Dehumidifier: For homes with persistent humidity problems, a whole-house dehumidifier can be a worthwhile investment.

One often overlooked area is the crawl space. Many Denver homes have crawl spaces that are poorly ventilated and prone to moisture. Ensure your crawl space is properly sealed and ventilated to prevent mold growth. Consider encapsulating the crawl space with a vapor barrier to prevent moisture from entering.

Another critical point: don’t ignore musty smells, even if you can’t see any visible mold. Mold can grow behind walls and under floors for months before it becomes visible. If you smell a musty odor, investigate further.

Finally, remember that mold is a common problem in Denver, but it’s also a manageable one. By understanding the risks, taking preventative measures, and acting quickly when problems arise, you can protect your home and your health. Don’t let the altitude and air conditioning create a hidden mold problem. Be proactive, be vigilant, and breathe easy.