Multi-layered thermoplastic roofing membranes

A multi-layered membrane comprising:

• (i) a top layer including an ethylene-based olefinic block copolymer;
• (ii) an upper-middle layer including a propylene-based elastomer;
• (iii) a lower-middle layer propylene-based elastomer;
• and
• (iv) a bottom layer including an ethylene-based olefinic block copolymer, said top layer and said bottom layer forming said skin layers, and said upper-middle layer and said lower-middle layer forming said core layers, where the skin layers include at least 40 weight % an ethylene-based olefinic block copolymer based on the total polymeric content of the layer, where the core layers includes greater than 15% by weight propylene-based elastomer based on the polymeric content of the layers, where the top layer includes greater than 25% by weight magnesium hydroxide based upon the entire weight of the layer, and where the core layers include greater than 25% by weight calcium carbonate based upon the entire weight of the layer, wherein the top and bottom layers are substantially devoid of propylene-based elastomer.