What is "underlayment"

n. Something that is underlaid, such as planking in a room of a house; underlay.

n. a pad placed under a carpet [syn: carpet pad, rug pad, underlay]

Underlayment may mean:

• Underlay, a material placed underneath floor carpet, other flooring materials, or mattress bedding.
• Underlayment, a water resistant or waterproof layer used beneath many types of commercially available roofing material
  • Bituminous waterproofing
  • SDM strength film
  • Tar paper
• Underlayment in road construction such as nonwoven fabric
• Underlay, a material in sewing
• Underlay, a technique in some types of surgery such as myringoplasty
• Underlay, a material in printing