The Department of Energy (DOE) and Oak Ridge National Laboratory (ORNL) have developed an innovative new design tool that will put building science expert advice in the hands of every building designer who cares to manage moisture risk in high-R envelope components. As modern residential buildings become increasingly more airtight, are constructed with modern laborsaving materials, and are equipped with air-conditioning, they have become less forgiving of moisture intrusion. The Building Science Advisor (BSA) provides building science knowledge and advice based on expert experience, field measurements, laboratory tests, and computer simulations. BSA users are prompted to enter relevant information about the building location, design, and material selection options, such as cladding, the structural system, and insulation. Influential factors such as climate, building air tightness, material properties, and internal moisture loads are also considered to estimate and compare the moisture durability performance of several design options. If the BSA deems the assembly's performance unsatisfactory, it will provide the reasons why and suggest necessary changes to wall design to ensure more robust performance. Using the BSA tool enables building designers to confidently select residential assembly design characteristics that achieve their design goals with the least moisture durability risk. Links to design-specific guidance are also provided to help users manage any remaining risk. This tool will further enable DOE's Building Technologies Office (BTO) to meet its long-term energy goal of a 50% reduction in building energy consumption by reducing builder concern about using highly energy-efficient wall systems.