The answer to 'cost to replace underlayment in Chicago' is that the cost can vary significantly depending on several factors. Generally, the cost to replace underlayment in the Chicago area can range from $2 to $5 per square foot, but this is just a rough estimate.
The actual cost will depend on the size of your roof, the type of underlayment material used, the complexity of the roof, and the labor rates in your local area. Additionally, if there is any damage to the roof deck that needs to be repaired, that will add to the overall cost. It's best to get quotes from multiple roofing contractors in your local Chicago area to get a more accurate estimate for your specific project.