Is Fiberglass Insulation Ruined if It Gets Wet?
Fiberglass batts and loose fill insulation provide a cost-saving solution to high heating and air conditioning bills. For best results, fiberglass should be installed in a dry cavity within your walls or attic joists, says Fine Homebuilding. If the fiberglass becomes wet its performance is compromised, but in many cases it will regain its effectiveness as the material dries out.
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How Fiberglass Insulation Works
Fiberglass insulation forms a feathery network of tiny air pockets that collectively serve to resist the transfer of warm air from indoors to out in the winter, and from outdoors to indoors in the summer, reveals the U.S. Department of Energy. You should never force too much fiberglass insulation into a small place because compressing the fiberglass reduces the number of air pockets and that makes it less effective as an insulator. For that reason it’s also important to keep dirt or moisture from contaminating your fiberglass insulation and filling in the air pockets.
Keeping Insulation Dry
When fiberglass insulation gets wet, water droplets displace the air in the spaces between the fine glass fibers which greatly reduces the material’s thermal and acoustic insulating abilities. To prevent this from happening it’s important to caulk and seal any gaps in the home’s exterior wood sheathing that might allow water infiltration during heavy rainfall. Although the fiberglass itself has been treated with a mildewcide, mold can still form on dirt and mineral deposits that might remain after moisture has evaporated.
Coping With Wet Insulation
If the fiberglass within your wall cavity or in your attic becomes wet from a leaky roof or burst pipe it will lose insulating effectiveness until the material dries out over time, reports Owens Corning. However, if the fiberglass batts or loose fill insulation becomes inundated with dirty flood water and becomes soaked throughout, the fibers may become cemented together with dirt and form clumps. Compressed or contaminated fiberglass will no longer be very effective as insulation and it should be replaced.
Testing Your Insulation
An infrared thermometer is an effective device for measuring the performance of your insulation without removing the drywall panels from your interior walls. Simply compare the temperature of an area where the fiberglass has become wet with similar portions of your wall or ceiling that were not affected by moisture to see if the insulation’s performance has been compromised. A large difference in temperature would indicate that the insulation should be replaced. Infrared thermometers are a relatively economical purchase, but you can also rent them for short-term use.
Mike Matthews is editor of Green Building Product News, a national publication that covers sustainable innovations in building and remodeling, and he has spoken at national conferences on green building. He has also served as founding editor of “Paint Dealer” magazine.