Dehumidification: Why Humidity Control Matters for Indoor Air Quality
Indoor air quality gets a lot of attention these days, but humidity control is usually the missing piece. If the humidity in your home or workplace is off, you’ll feel it long before you know what the problem actually is. Too high and everything feels damp and heavy. Too low and you feel like you’re drying out from the inside.
Humidity affects comfort, health, allergens, mould growth, and even the long-term condition of your building. There are two kinds of dehumidification you need to know about. One is for everyday comfort. The other is structural drying, which has nothing to do with comfort and everything to do with protecting the integrity of your home or office.
1.Comfort Dehumidification (Managing Relative Humidity)
For everyday living and working, the ideal relative humidity sits between 40 and 50 percent. That range keeps the air comfortable, reduces dust mites and allergens, and prevents moisture problems from creeping in.
On Vancouver Island, especially in fall and winter, the outdoor humidity regularly hits close to 100 percent. That moisture pushes its way into homes and office buildings. I’ve been inside houses sitting at 80 to 90 percent humidity, and that level feels awful. Sleep gets worse, dust allergies spike, and the whole space feels sticky and heavy.
Dry the place too much, around 30 percent or lower, and now you’re dealing with dry skin, a scratchy throat, and enough static electricity to make your kids jump.
For comfort control, you’re typically using refrigerant dehumidifiers. These are the units you find at Home Depot, Walmart, Canadian Tire, and similar stores. They usually cost anywhere from $100 to $500 and work best in temperatures above 20°C, where they pull the most moisture out of the air.
There are industrial versions too. They’re built to run longer and handle larger spaces or commercial environments.
2. Structural Drying (Moisture Inside Walls and Building Materials)
Structural drying is a different job entirely. You’re no longer drying the air, you’re drying the building materials themselves—studs, subfloors, sheathing, drywall, insulation, sill plates, all the things that actually hold the building together.
When I worked in equipment rentals, I set up structural drying systems for construction projects. Even with the roof on, framing lumber can end up soaked during the build. Once the exterior wrap went on, builders would call me in to set up heaters, fans, and commercial dehumidifiers to dry out the structure.
In BC, the moisture content in framing lumber must be below 19 percent before you close the walls. High-end builders take it even further, drying materials down to 8 to 12 percent to prevent issues with finishing later on. Drywall screw pops, warped trim, shifting walls—those problems show up when the structure wasn’t dried properly.
Structural drying is also needed after floods or water damage. A burst pipe, overflow, or leak can push moisture deep into the structure where it starts causing problems behind the scenes.
You usually see two technologies used for structural drying:
Refrigerant Dehumidifiers
Best when indoor air is warm (20°C and above)
Good for standard construction drying
Slower than desiccant units
Less effective in cold spaces
Desiccant Dehumidifiers
Work in cold environments (down near 0°C)
Pull moisture faster
Use more energy
Ideal for large floods, big commercial spaces, or soaked building materials
Desiccant systems are the powerhouse option. If you need to dry something fast or the temperature is low, they’re the right tool for the job.
Why Humidity Control Matters for Indoor Air Quality
Humidity ties into everything. High humidity creates a perfect home for mould and dust mites. Low humidity dries out your sinuses and impacts comfort. Even the best HEPA filter in the world can’t fix poor humidity control.
Good air quality comes from balancing filtration, fresh air, and humidity levels. When you get those right, everything else gets better.
Call to Action
If you're dealing with indoor air quality complaints, moisture issues, or concerns about your building’s humidity levels, I offer a free review of your current health and safety program and/or space. I can help you identify risks, improve comfort, and prevent costly issues down the road.
