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Q & A session with Anthony DeMiglio, President at AMD Environmental Consultants

Q & A session with Anthony DeMiglio, President at AMD Environmental Consultants

AMD Environmental technicians come across many problems in homes caused by ventilation imbalances.

A question that is often asked is:

How do ventilation imbalances cause moisture problems?

Anthony DeMiglio, President at AMD Environmental, answers frequently asked questions related to proper ventilation and moisture control.

Q: What are ventilation imbalances?

A: Ventilation imbalances have the potential to create a lot of problems in your home. This means the air pressure in the home is not evenly distributed, temperatures in the home vary from room to room, or moisture is evident.

We see this mainly when people renovate homes older than 30 years old. Energy efficiency of materials and building products have changed, but the structure of the home may not be able to handle energy efficient upgrades without accounting for proper ventilation. On one hand, you are increasing the efficiency of your home and potentially saving money. On the other hand, this could possibly create problems with moisture – ultimately leading to mold growth.

Q: When are ventilation imbalances caused?

A: We typically see ventilation imbalances after people renovate older homes, particularly, when trying to make the home more energy efficient. This includes installing a new furnace, new windows, or a change to the roof ventilations. All of these energy efficient upgrades have potential to change the pressure and relative humidity inside a home, therefore, increasing moisture or the potential for moisture build up.

Q: Will installing a gas fireplace affect the moisture in my home?

A: Yes. A gas fireplace releases a lot of moisture and increases the relative humidity inside a home. Wall units especially kick out a lot of moisture trapping the moist air inside the home. Proper ventilation needs to be accounted for in order to avoid giving mold opportunities to grow.

Q: How do energy efficient upgrades cause ventilation imbalances?

A: Older homes in particular are not airtight. Houses let air stack through the roof from the basement. Moisture may not have been a concern because of a drafty roof or some other cracks or opening in older windows or doors. Once you change the structure to be airtight, the moisture isn’t able to dissipate or escape as it once did. This is when homeowners start to see an increase in the relative humidity with possible mold growth or unusual odors as a result.

Q: How will I know if moisture is a problem in my home?

A: Some problems are easier to detect than others. For example, if you have new windows installed without considering other ventilation measures, you may see what is called “sweaty windows.” The relative humidity increases in a home, causing condensation to build up on the inside of the windows. This is because moisture can’t leave the house the way it once did.

Moisture problems may also present themselves in the form of “ghosting.” This occurs when an unvented gas fireplace (wall unit) kicks out carbon, staining your walls black.

Bathrooms are another source of moisture if not properly ventilated. Since bathrooms are the wettest spaces in the home, you will want to make sure your fan is relative to the square footage of the bathroom and properly vented to the roof. An easy way to fully air out the space is to run the vent for about 20 minutes after a shower. If you are one of those people who shower and jet out the door, consider a fan with an automatic humidity sensor or an adjustable timer. The convenience is that when the humidity levels are too high, the fan automatically kicks on and off.

Q: What can I do to prevent ventilation imbalances?

A: The first thing you should do is be aware of the problems that can occur before renovating an older home. If you renovate a space or install new windows, contact a roofer or contractor to see how you can increase venting in the attic based on cubic footing.

Q: Can I build a house that is “too tight?” 

A: People ask this question a lot! The answer is no. Tight is good, but underventilated is bad! Tight construction can reduce a major issue called ice dams. Ice damming occurs when hot air moves into the attic and the house can’t get rid of the heat. The ice builds up on the eave of a slanted roof because the snow underneath melts. The meltwater flows down the roof until it reaches a point where there is no longer heat from the home. The meltwater freezes and forms a dam. This has potential to cause structural damage to the roof and leak inside the home. So sealing up air leaks into the attic is a good way to prevent ice dams from building up. Remember, tight is good – underventilated is bad.

Q: How can AMD Environmental Consultants help me with ventilation imbalances in my home?

A: AMD Environmental Consultants has been advising homeowners for over 10 years. Collectively, our experts have decades of experience dealing with structural issues, ventilation imbalances, and other factors contributing to toxic mold growth. For more information, contact (716) 833-0043, follow us on Facebook and LinkedIn, or visit,