This knowledge product explains the rationale and procedures for incorporating allowances for climate change in detailed engineering design, with a focus on credible adjustments to extreme rainfall and to mean and high-end sea-level rise. Highlighting worked examples drawn from Viet Nam's road transport sector and peer-reviewed research literature, it offers a point of departure for more sophisticated assessments of high-risk projects. It presents principles and approaches extendable to other design variables (extreme air temperature, evaporation, and wind speed) and transferable to other sectors, regions, and stages of the asset life cycle (from project concept to decommissioning). An accompanying step-by-step manual shows how each calculation is performed.