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How to Dry Wet Insulation in an Attic

Originally posted on Men's Journal | By Max Winters | Last updated Dec 27, 2024 11:30 AM ET

Wet insulation in your attic or loft is a sneaky problem that can cause more damage than you might think. Beyond the potential for mold and mildew, soggy insulation loses its fluff factor that gives it a thermal efficiency. This creates an energy loss as heat (or air conditioner efforts) go right out of your home and jack up your energy bills. Regardless what's to blame, with insufficient ventilation it’s imperative that you act quickly to dry the attic out to avoid long-term issues.

How long does it take to dry wet insulation?

The drying time for wet insulation depends on factors such as the type of insulation, the amount of water, and the air circulation conditions. On average, fiberglass insulation can dry within 2-3 days under ideal circumstances, while cellulose insulation, being more absorbent, may take several days or longer. Spray foam insulation is less susceptible to water damage, but repairs might be necessary if it becomes compromised, trapping water in a closed wall cavity or insulating moist wood. To accelerate the drying process, use extractor fans, dehumidifiers, and ensure proper ventilation.

You'll Need

High-powered fans or blowers
Dehumidifier
Plastic sheeting
Protective gloves and mask
Moisture meter
Utility knife or scissors
Garbage bags (if removal is required)

1. Assess the Damage

Inspect the insulation to determine the extent of saturation.
Use a moisture meter to check dampness levels in the wet material.
Look for signs of mold or mildew, especially if the insulation has been wet for an extended period.

2. Improve Ventilation

Open attic windows or vents to allow for airflow.
Place high-powered fans near the wet areas to circulate air.
Consider adding a dehumidifier to remove excess moisture from the air.

3. Remove and Dry Wet Insulation

For fiberglass batts, carefully lift out the wet sections and place them in a dry area with good ventilation.
Spread out cellulose insulation on a clean surface with plastic sheeting underneath and use fans to dry it.
If insulation is moldy or severely saturated, bag it up for disposal and prepare for replacement.

4. Address the Source of Water

Check for roof leaks, dripping pipes, or any nearby water source for leaks.
Check for structural damage and repair the issue to prevent future water damage.

5. Reinstall or Replace Insulation

Once fully dry, reinstall the insulation in its original location.
If the water-damaged insulation is beyond salvage, replace it with new material.

FAQ

How do I know if my insulation needs to be replaced?

If the insulation remains damp after several days or shows visible mold growth, it should be replaced. Moldy or sagging insulation will not perform effectively, cause musty smells, and can become a health hazard causing poor indoor air quality, respiratory issues, or even asthma attacks.

Can I dry wet insulation without removing it?

It’s possible to dry slightly damp insulation in place using fans and a dehumidifier, but heavily soaked insulation should be removed to prevent mold and musty odor issues.

Is it safe to handle wet insulation?

Wet insulation can harbor mold and bacteria. Always wear gloves, a mask, and protective clothing to avoid direct contact and inhalation risks. Get it out of the wall cavity and get it out of the living space.

This article first appeared on Men's Journal and was syndicated with permission.

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