I don't see why you couln't build the surround with steel studs & durock, but it's definately more work than just using concrete block, & nowhere near as strong. There is no way you can build the throat, smoke chamber, & flues from tile board! They wouldn't make it thru 1 good fire. :no: Depending on the size of firebox you planning, you can get these components fairly cheap. Throat sections (3) with coved ends to meet firebrick = about $350. 13" x13" x 24" flues = about $25 a peice. You can also make your own smoke chamber out of 2 flues to save yourself about $100. Check out rumford dot com for a ton of info on fireplace kits. I've done quite a few rumfords, & am in the process of building a 32" outdoor at my own house right now, and can verify that the fires can easily reach over 1500 degrees, probably closer to 2000 degrees at times. I have a good infared pyrometer, & it always maxxes out when aimed into the fire. This tells me there's no way the durock & steel studs will work.