Homeowners ask us this a lot. The honest answer is that it depends less on the calendar and more on what your attic has been through. Insulation that stays dry, clean and undisturbed can work for a very long time. Insulation that’s been soaked, packed down or lived in by rats may be done in a few years.
What wears insulation out
- Moisture. Humid air and roof leaks flatten insulation and can lead to mold.
- Settling. Loose-fill insulation slowly packs down and loses height.
- Pests. Rodents tunnel through it, nest in it and leave droppings behind.
- Disturbance. Every AC, cable or electrical job can push insulation aside.
- Not enough to begin with. Many older homes were built with much less insulation than we’d put in today.
Signs it’s time to replace or add more
- You can see the tops of the joists
- Your upstairs or some rooms run hotter than the rest
- Your AC runs long cycles on hot afternoons
- The insulation looks gray, dusty, stained or clumped
- There’s a musty or sour smell in the attic
- Your cooling bills have crept up and nothing else changed
Our post on the top signs you need new attic insulation goes through these in more detail.
Does old insulation need to come out?
Not always. If it’s dry, clean and just thin, we can usually blow new insulation right on top of it. That’s often called a top-off. If it’s wet, moldy or full of pest mess, it should come out first so you’re not sealing a problem under fresh material. You can read about both on our attic blown-in and removal and replacement pages.
How to make new insulation last
- Fix roof leaks and AC drain problems right away
- Make sure bath fans vent outside, not into the attic
- Keep pests out by sealing entry points
- Ask anyone working in your attic to put the insulation back when they’re done
- Take a quick look from the hatch once a year
Does fiberglass last longer than cellulose?
Both can last a long time when they stay dry and undisturbed. Fiberglass doesn’t absorb water the way paper-based cellulose does, so it tends to hold up a little better in damp Florida attics. Cellulose can settle more over time. Our post on fiberglass vs cellulose compares them.
Common questions
My house is only 15 years old. Could the insulation already be worn out? It can be, especially if there’s been a leak, pests or a lot of work done in the attic. Age alone doesn’t tell you much. A quick look does.
Should I replace it before I sell? If it’s in rough shape, it may show up on a buyer’s inspection report. See our post on whether insulation adds home value.
How often should someone check it? A quick look from the hatch once a year, and after any storm or roof repair, is a good habit.
Not sure what you have?
We’ll measure what’s in your attic and tell you honestly whether it needs anything at all. REINSULATE is a veteran-owned, fully insured insulation company serving Bradenton, Sarasota and the rest of Manatee County. Request your free estimate or call or text 941-705-0305.
