The answer to 'underlayment vs' is that underlayment and shingles are both essential components of a complete roofing system, but they serve different purposes. Underlayment is a water-resistant barrier that is installed between the roof deck and the shingles, providing an extra layer of protection against moisture intrusion. Shingles, on the other hand, are the visible outer layer of the roof that protects the home from the elements and provides aesthetic appeal.
Underlayment is typically made of materials like asphalt-saturated felt, synthetic polymer, or rubberized asphalt, while shingles can be made of various materials such as asphalt, metal, tile, or slate. Underlayment is generally less expensive than shingles, but the choice of underlayment and shingles will depend on factors like the local climate, the roof's pitch, and the homeowner's budget and preferences.