When are less durable underlayments typically accepted in roofing?

Less durable underlayments are typically accepted in roofing when they are paired with shorter lifespan coverings. This is because shorter lifespan roofing materials do not require as sturdy or long-lasting support as those designed for more extended use. For instance, if the primary roofing material is designed to last for a decade or so, it would be reasonable to use an underlayment that is less durable, as the overall expected lifespan of the roofing system will be shorter.

In contrast, materials designed for a longer lifespan would necessitate more durable underlayments to ensure that the roofing system performs effectively over an extended period and provides adequate protection against elements like water infiltration. This principle underscores the importance of matching the durability of the underlayment with the expected lifespan and durability of the roofing material being used.