Abstract: A moisture detection sensor is used in a building structure to detect moisture penetration is a flat self-adhesive tape. It includes a substrate of dielectric, hydrophobic material. Two elongate, parallel, conductors are secured to the top surface and a protective layer of non-hygroscopic, water pervious material secured over the conductors. A pressure sensitive adhesive on a bottom surface of the substrate is covered with a release sheet. The sensor may include moisture probes which penetrate the protective layer, the respective conductors and the substrate and to extend into a building component to which the substrate has been adhered. Each probe is made from a conductive, corrosion resistant material. This is particularly useful with water absorbent building materials, such as wood, where the surface may appear dry, but the body is impregnated with water. The preferred moisture probe is a U-shaped metal staple driven by a power stapler.