If you’re thinking of installing a new roof, one of the first things to ask when working with a contractor is what type of underlayment they will be installing. You may be wondering, “What is underlayment, and why is it important?” Underlayment is the waterproofing material or membrane installed underneath your shingle or tile roof. There are two types of materials used today–felt and synthetic underlayment. Felt underlayment is made up of cellulose, polyester, bitumen, and asphalt. Felt is available in two thicknesses: fifteen-pound and thirty-pound. Thirty-pound felt is thicker and stiffer than fifteen-pound, so thirty-pound is more resistant to damage during installation and can protect the roof longer if exposed to outside elements like wind, rain, or snow. Synthetic underlayment is typically made from woven or spun polyethylene or polypropylene, and it comes in a variety of different thicknesses to suit your needs. These usually weigh less than traditional…