Yes and no (personal experience. Lowe's is the contractor, period. So they are responsible. However, you'll note your contract has an arbitration clause. If Lowe's decides to not take responsibility, you can be completely stuck.
Lowe's installed a new floor in our home. The floor is defective. We tried for a full year to get Lowe's to make it right, and they simply ignored us. Dozens of emails, phone calls and letters were sent. Lowe's contracts have an arbitration clause forbidding the customer from suing them. When we finally sent an arbitration demand, they ignored that also. In desperation, we did sue them. The judge agreed and sympathized, but ruled that their arbitration clause is enforceable, even if they ignore our demand. People who do business with Lowe's should be aware that if they screw up, you're stuck. All they have to do is ignore you