Introduce of underlay

underlay generally refers to a thin layer of cushioning made of materials such as sponge rubber, foam, felt, or crumb rubber; this material is laid beneath carpeting to provide comfort underfoot, to reduce wear on the carpet, and to provide insulation against sound, moisture, and heat.In general, it is a layer which is underneath another layer,so underlay is thus also used to describe many different surface-covering products.

A self-leveling underlay is a cement-like product that can be pumped in liquid form onto the floor in order to create a level floor.

underlay is also the term for the material under roofing tiles;this roofing membrane is often made of rubber and is used to seal the roof and prevent leakage. underlayused with roofing shingles provides a second layer of water proofing to prevent leaks and is called tar paper, roofing felt, or since the 1990s synthetic underlay.