Prevalence of New Zealand’s unreinforced masonry buildings

Abstract

Unreinforced masonry (URM) buildings remain New Zealand's most earthquake prone class of building. New Zealand URM buildings are classified into typologies, based on their general structural configuration. Seven typologies are presented, and their relative prevalence, age and locations are identified. There are estimated to be 3,750 URM buildings in existence in New Zealand, with 1,300 (35%) being estimated to be potentially earthquake prone and 2010 (52%) to be potentially earthquake risk, using the NZSEE Initial Evaluation Procedure. Trends in the age of these buildings show that construction activity increased from the early days of European settlement and reached a peak at about 1930, before subsequently declining sharply. The preponderance of the existing URM building stock was constructed prior to 1940, and as such, almost all URM buildings in New Zealand are between 80 and 130 years old (in 2010). Overall the URM building stock has a 2010 market value of approximately $NZ1.5 billion, and constitutes approximately 8% of the total building stock in terms of floor area. Details are also provided regarding the development of New Zealand building codes and the associated provisions for assessing existing earthquake risk buildings, and provides some background to the history of the URM building stock in New Zealand.