Sorry for another noob question but after finally having my hearth framed and 3 layers of cement board applied, I ran into a problem. I used metal studs for the air space on the hearth pad (the cheap Home Depot ones) and I noticed when walking on the pad there was A LOT of flex in the floor. I did not use thin set between the cement boards which I know now would help. But I noticed the metal studs are flexing also. The studs are 25 ga, would getting 16 ga be much better and make the issue of flexing obsolete? Or should I use something else to create an air space below the pad? I would love to use micore but unfortunately no one sells it in the area. If anyone has used the thicker metal studs I would appreciate feedback on how it turned out for you. And I am open to any suggestions. The stove going on the pad will be tnc30 which requires r=1.50. Thanks in advance for the help, much appreciated.