Don't Fret if It's Wet! Let it Dry!

At Johns Manville, we’re more than just a manufacturer. We want to help those who use our products any way we can. So, when you have a question, we’re not only going to respond, but we’re going to get our product experts to give you the best answer possible. We recently received the following question from one of our customers:

"What’s JM’s recommendation for wet unfaced insulation after being saturated with water? What effects does the water have on R-value and the product performance? I read online that it leads to a 40% loss of R-value—is that right?”

JM Unfaced Formaldehyde-free™ fiberglass insulation offers R-values ranging from R-11 to R-38, as well as effective thermal and noise control. But what do you do if it gets wet? Well, it depends. If the product was saturated due to flooding, the product must be replaced since it will have been contaminated with dirt and other foreign materials that can provide a food source for mold. If it gets wet by fresh water, just dry it out. If the insulation is allowed to completely dry and retains its previous thickness, the product will keep its thermal and acoustical properties.

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Drying your insulation isn’t hard to do at all—in fact, it’s kind of a “set-it-and-forget-it” process. The first step is to remove the insulation for an overall assessment while allowing the framing to dry—just be sure to use the right protection (safety glasses, gloves, and long sleeves) since you’re dealing with fiberglass. The easiest way to dry out your insulation is to use fans and a dehumidifier. Simply place the dehumidifier and fans near the removed insulation, turn them on and dry. You can even put the insulation in the sunlight or a warm/dry area. Keep checking back now and then to see if the water is evaporating out, and when it’s dry, you’re set. After reinstalling the insulation, reexamine it in a few weeks to make sure there’s not a musty/moldy smell. If there is, you’re going to have to replace it. If not, you’re good to go.

When it comes to wet fiberglass insulation, it’s possible to dry it out. The R-value won’t degrade and as long as your insulation wasn’t contaminated with flood water, you’ll be safe. When in doubt, dry it out!

Come back soon to read more about other DIY tips and tricks for your home.