Attached underlayment works as a water, sound and temperature barrier
Attached or separate underlayment for laminate flooring has many protective functions which prolong life span of laminate. It provides stability and allows laminate flooring to naturally breathe. Attached underlayment is used as a water barrier to protect laminate flooring against humidity from subfloor. Humidity can cause swelling of laminate planks and growth of mold. If this happens, planks have to be replaced with new ones. Attached underlayment is also very good sound and temperature isolator. Walking on laminate flooring without attached padding can be very loud, so attached underlayment dampens the sound. This is especially important in multi story buildings.