A damp and humid garage can cause problems for homeowners, such as mold and mildew growth, rusted tools and corrosion of automotive parts. To keep moisture under control, start with the simplest solutions first, and progress to more costly and labor-intensive remedies if humidity continues to be a problem.
Step 1: Protect your tools
Until you get humidity under control, throw a few packets of silica gel in your toolbox; they’ll absorb moisture and help protect your tools from rust.
Step 2: Keep water out
If your car is wet from the rain, and you park in your garage, that moisture is going to evaporate inside and raise humidity levels. Towel-dry your wet car before closing the garage door. In the winter, don’t allow wheel-well icebergs to melt in your garage. (Usually, these can be removed with a swift kick).
Step 3: Get rid of cardboard
Mold needs a food source in order to grow, and many species of mold thrive on cellulose, a primary component of paper and cardboard. If, like most people, you have cardboard storage boxes in your garage, replace those with airtight plastic tubs.
Step 4: Improve ventilation
If your garage doesn’t have windows that open, consider installing a ceiling fan to keep air circulating. An exhaust fan – which can be installed either in an external wall or the ceiling – can help pull moist air out of your garage, as can a portable dehumidifier.
Step 5: Improve exterior drainage
Check the ground around your home to make sure it slopes away from your foundation at least six inches for the first 10 linear feet. A lesser slope – or a non-existent one – can cause excess groundwater to accumulate beneath a garage’s concrete slab. Add topsoil and adjust the grading, if necessary.
Detached garages may lack gutters and downspouts. Adding those can be expensive, but they will draw moisture away from the structure and help prevent serious water-related problems, like rotting wood beams.
Step 6: Add windows
Sunshine can help dry-up a damp garage, so you might consider adding a new garage door with windows. A skylight that opens brings sunlight into the garage and improves air circulation. Some newer skylights collect solar energy to power their battery-operated opening and closing functions, and windows close automatically when their sensors detect rain.