Quick Answer
Wool insulation becomes significantly heavy when wet, typically around 50-60% of its dry weight, due to its natural fibers absorbing water.
Water Absorption and Weight Increase
Wool insulation can absorb up to 30% of its dry weight in water before reaching saturation. This is significantly less than many synthetic insulations, which can absorb much more water before becoming saturated. A 1-inch thick layer of wool insulation can weigh around 1.5-2 pounds (680-900 grams) when dry, but can increase to 2.25-3 pounds (1.02-1.36 kilograms) when fully saturated with water.
Comparison to Synthetic Insulation
Synthetic insulations like polyester or fiberglass can absorb up to 50-70% of their dry weight in water before reaching saturation. This difference in water absorption can greatly affect the overall weight and performance of the insulation when wet. For example, a 1-inch thick layer of polyester insulation can weigh around 1-1.5 pounds (450-680 grams) when dry, but can increase to 3.5-5.5 pounds (1.59-2.49 kilograms) when fully saturated with water. This weight increase can make the insulation more difficult to carry and use in wet conditions.
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