Tar paper, or asphalt-saturated felt underlayment, has historically been the go-to choice for roof underlayment. However, a few challenges are associated with this type of underlayment. First, since it’s usually available in 2 or 4 square rolls, it can take many rolls to complete an average-sized roof. The installation can also be difficult because this underlayment tends to buckle and wrinkle. Lastly, it’s important to know that as a paper product, the material can degrade quickly. If you’d prefer, there are other underlayment options available.