Impact of increased design wind speeds on residential construction costs in the Philippines

Abstract

Buildings in the Philippines are designed for wind speeds of 150, 200 or 250kph depending on the region where they are located. In 2013, tropical cyclone Haiyan brought about record high wind speeds of about 307kph at landfall. It led to the collapse of 550,928 houses and partially damaged 589,404 others. Professional organizations for civil engineers and architects in the Philippines propose to modify the design wind speeds specified in the National Structural Code of the Philippines (NSCP) in order to make structures more resilient to typhoons that are both intensifying and changing direction. This research seeks to analyse the impact of such changes on the cost of constructing and/or reconstructing homes. A house model by the National Housing Authority was modelled and redesigned for increased wind speeds. Corresponding increments in the construction costs were computed. The results demonstrate considerable increase in the cost of the roof framing and sheathing in the lower wind speed ranges, and the cost of required steel reinforcements for higher wind speeds. The study contributes to the body of literature in verifying the feasibility of proposed modifications to design wind speeds in the building code.