What type of material is typically used for roofing underlayment?

Asphalt felt is typically used for roofing underlayment due to its effective moisture resistance and durability. This material acts as a protective barrier under shingles, preventing water and moisture from permeating into the roof structure. Its composition allows it to withstand the elements while providing an extra layer of insulation and protection against leaks.

Other materials listed can have their uses in construction, but they do not serve the same purpose as roofing underlayment. Metal roofing products may act as a roofing system itself but are not utilized as underlayment. Fiberglass is commonly used in insulation and other applications but is not ideal for roofing underlayment purposes. Wood may be used in structural components but lacks the moisture control properties that asphalt felt provides, making it unsuitable for underlayment. Thus, asphalt felt's unique characteristics make it the preferred choice for roofing underlayment in most applications.