Corrugated Stainless Steel Tubing (CSST) has been used since 1989. It replaces the traditional iron pipes for plumbing natural and liquid petroleum (LPG) gas throughout the house. CSST is flexible, easier to install due to fewer connections, and cheaper for the builder to install saving the house buyer money.As with many new products, several unintended consequences have appeared which must be taken into consideration. These include the high likelihood of damage from lightening, or damage from nails. Since the walls of CSST are easily penetrated, gas leaks can happen more easily. Many contractors install CSST too close to the roof sheathing, which exposes the CSST to damage when the roofing material is installed or replaced. Home inspectors need to carefully inspect this plumbing system for proper grounding and protection from damage. The image below shows a roof nail that nearly punctured the CSST. CSST is under investigation and its installation has already been halted in Massachusettes.