Improved pipe-coating materials (10) and methods, and improved coated pipes (30) formed thereby, in which a thermally insulating coating is formed from a strip of striated insulating material (10), such that individual bars (16) of said insulating material are isolated from one another and encapsulated by water-impermeable barriers in the finished coating, whereby water ingress into any one bar of said material will be restricted thereto, thereby allowing the use of materials, including open-celled foams, which would otherwise be vulnerable to water penetration. Also disclosed are means for improving impact resistance, improved methods of forming striated insulating materials and improved means for tensioning strip-like insulating materials as they are helically wrapped upon a pipe or the like.