Why insulation loses performance
- Settling and compression. Loose-fill insulation settles over time, and storage boxes or foot traffic crush it.
- Moisture. Wet insulation loses much of its R-value and can feed mold.
- Pests. Mice, squirrels and raccoons tunnel through, nest in and contaminate insulation.
- Old standards. Homes built decades ago were insulated to much lower levels than R-50.
8 signs your attic needs attention
- Upstairs rooms are colder in winter or hotter in summer than the main floor.
- Heating and cooling bills keep rising with no other explanation.
- Ice dams or icicles form on the roof in winter.
- You can see the tops of the ceiling joists from the hatch.
- Insulation looks flattened, patchy or uneven.
- There are droppings, nests or a musty smell in the attic.
- Insulation is stained, damp or clumped.
- The roof sheathing above has dark staining or frost on the nails.
2-minute DIY check
With a flashlight and ruler, look in from the hatch without stepping off the joists. Push the ruler down to the drywall in a couple of spots. Under about 10 inches of cellulose or 14 inches of fiberglass means you're well below R-50. Any staining, damp or droppings means it's time for a professional look. See our R-value depth chart.
Top-up or replace?
If the existing insulation is dry and clean, a top-up is usually all you need. If it's wet, mouldy, contaminated by pests or badly compressed, removal comes first.
FAQ
Does attic insulation need to be replaced every few years?
No. Dry, undisturbed insulation can last for decades. It usually needs a top-up because it was never deep enough or has settled, not because it wore out.
Can old insulation make my house unhealthy?
Insulation contaminated by rodents, mold or moisture can cause odours and allergens. In that case, removal before re-insulating is recommended.
How do I know if I have vermiculite?
Vermiculite looks like grey-brown or gold pebbles. Don't disturb it; have it tested first, because it may contain asbestos.