For roofing felt, what type of material can be considered?

Roofing felt, often referred to as underlayment, is primarily designed to provide a secondary layer of protection and is typically composed of a specific type of material that offers resilience and water resistance. Fiberglass is an appropriate choice for roofing felt because it provides excellent durability, dimensional stability, and resistance to moisture and mold. Fiberglass mat-based roofing felt is lightweight yet strong enough to withstand the elements, making it suitable for use beneath shingles or other roofing materials.

The other materials listed, such as cardboard, metal, and polyethylene, do not serve the same purpose or possess the same beneficial properties as fiberglass in roofing applications. Cardboard is not durable enough for roofing use, as it can deteriorate quickly when exposed to moisture. Metal, while used in various roofing applications, is not suitable as a felt material due to its rigidity and lack of flexibility. Polyethylene is primarily a plastic material and does not provide the necessary waterproofing and structural characteristics needed for roofing felt. Thus, fiberglass is the most suitable and commonly used material for roofing felt in various roofing systems.