Outdoor construction workers in Malaysia, India and the Maldives face increasing workplace heat exposure that threatens physical safety, attention, judgement and workplace well-being. This 24-month CAPaBLE project will strengthen practical regional capacity to assess and reduce workplace heat risk through a harmonised protocol, training and supervised field practice. Sixty early-career researchers and practitioners, 20 per country, will be trained in WBGT, air temperature, relative humidity, structured site observations, and brief, non-diagnostic, worker-reported measures. A planning cohort of approximately 450 construction workers, about 150 per country, will support supervised assessment of thermal discomfort, fatigue, perceived stress, concentration, safety and workplace well-being alongside environmental and occupational conditions. Workers, employers, and trainees will then prioritise and test one feasible physical or organisational heat adaptation measure or package in each country through two refinement cycles involving approximately 100 workers cumulatively. Outputs include a regional framework, three policy briefs, a practical toolkit, reusable training resources, country continuation plans, and a lightweight open-access resource page, reaching approximately 1,000 cumulative beneficiaries. The project does not undertake mental health first aid, psychiatric screening, diagnosis, treatment, biomarkers, or long-term disease assessment.