I have been lurking here for months and soaking up all the knowledge I can. This weekend, I am going to try and construct heat shield walls. Size and spacing is set (NFPA 211). But, could use some advice on construction. Plan: 1/2” Durock using 1.5” electric fence ceramic insulators as spacers. Never worked with cement board. Would like to add aluminum flashing to Durock. Considering drilling and riveting to achieve that. Any advice? Many thanks.