The answer to 'underlayment installation cost' is that the cost can vary significantly depending on several factors. Underlayment is an essential component of a roof system, providing a barrier between the roof deck and the roofing material. The cost of underlayment installation is influenced by the size of the roof, the type of underlayment material, the complexity of the roof, and the labor costs in your local area.
In general, the cost of underlayment installation can range from $1 to $5 per square foot, but it's important to get local quotes from roofing contractors to get an accurate estimate for your specific project. Factors like the type of underlayment (felt, synthetic, or self-adhering) and the roof's pitch and complexity can also impact the overall cost.