When was the last time you checked your attic insulation? Most people don’t think about it until there’s a major issue, like water damage or a roof repair. But insulation doesn’t last forever, and waiting too long can lead to expensive problems like mold, heat loss, or sky-high energy usage.
With spring cleaning season here, it’s the perfect time to do a quick inspection and ask a few key questions. Is your insulation still doing its job? How old is it? And most importantly, does it need replacing?
How Often to Replace Attic Insulation
Most insulation types lasts between 15 and 20 years, but that number isn’t a guarantee. In fact, most people might be shocked to know that it can "go bad" that quickly.
“Compromised insulation may lead to higher energy bills, moisture issues, and even health issues," shares Andrew Legge, CEO of Havelock Wool. "Early detection by an annual check can save from potential costly repairs later on.”
If your home is more than 15 years old and you’ve never had the insulation upgraded, there’s a good chance it isn't performing well. And I'm sure it comes as no surprise, but some older homes still have original insulation that’s compressed, moldy, and possibly even contaminated with pests. Once insulation starts breaking down, it simply doesn’t insulate anymore. You might not notice a change in your indoor comfort, but if you're paying attention, you'll see a gradual change in your monthly energy bills.
The type of insulation material also matters. Natural fibers like wool hold up better over time and resist attic moisture. On the other hand, synthetic materials, like fiberglass insulation, tend to suffer quickly when exposed to water, pests, or extreme temperatures. After a harsh winter or heavy rain season, it’s smart to give your attic a once-over and look for any signs of moisture damage, especially if you have issues with your soffit vents.
Signs Your Attic Insulation May Be Failing
Attic insulation problems are often easy to miss... until they start affecting your home’s comfort or energy bills. Some warning signs of wear to look out for:
- Uneven temperatures: If the indoor temperature difference varies throughout your living space, poor attic insulation might be to blame.
- Drafts or cold spots: You shouldn’t feel breezes inside the house if you have proper insulation. As wall insulation and windows age, it's more common to feel air leakage, but your ceiling should never experience heat flow.
- Mold or musty smells: Even if you don’t see mold, a damp, earthy smell can point to trouble with batt insulation and attic ventilation.
- Pest evidence: Scratching sounds, droppings, or holes in your current insulation could mean animals have moved in (fun).
- Visible damage: Wet spots, mildew, or dark stains are signs of water getting into the attic. Moist insulation is inadequate, and inadequate insulation is especially a concern. “Wet insulation does not work and needs to be replaced,” notes Legge. “It also molds very quickly, making at least an annual check worthwhile.” Again, moisture shouldn't happen if there's proper ventilation and no roof leaks.
- High energy bills: Heating or cooling systems may be working overtime due to heat transfer through poor insulation.
How to Inspect Your Attic Insulation
You don’t always need a pro to check your attic.
To start, you can also use an infrared thermometer to check for cold spots from below. HSFTools sent us the Finder S2, a thermal camera that attaches to our Android smartphone. It is SO GOOD. And what it revealed about air loss in our attic was SO BAD.
If it’s safe to enter and you feel confident doing a visual inspection, here’s what to look for:
- Mold or water stains on insulation or rafters
- Pests. Nests and rodent droppings are telltale signs.
- Compressed or sagging insulation that’s lost its shape
- Moisture or damp air, especially during warmer months
- Inconsistent insulation levels. Some areas may be thicker or thinner than others.
You can also check the thickness of your insulation while you're up there. Over time, it settles and may fall below the recommended R-value for your area. The U.S. Department of Energy offers R-value guidelines based on your climate zone. If you’re not sure what you’re looking at, taking a few photos and comparing them to online resources can help.
FAQ
What type of insulation lasts the longest?
Natural fiber insulation, like sheep’s wool, is a form of insulation that tends to resist moisture and pests better than synthetic options. “Wool has a natural ability to manage moisture and resist mold growth, which means it can last longer in real-world conditions,” shares Legge.
Can I add a new layer of insulation over old insulation?
Often, yes. As long as the old insulation is dry and free of mold or pests, you can add additional insulation on top without dealing with insulation removal. Blown-in insulation is a popular option for topping up without removing what's already there, but remember, even the new loose-fill insulation will also eventually settle, so be prepared to check back.
