There is no question that, with today's skyrocketing land prices, constructing an independent residence is getting increasingly difficult. However, analysts believe that concrete apartment complexes in India would endure just 30 to 50 years, as opposed to the expected 70 to 80 years. The reason is the lack of investment in maintenance and renovation which would be needed to keep up with rising standards of living and urban infrastructure. In fact, most independent houses in India's cities were built before 1970. Although some newer ones have been constructed with better quality materials, they are still vulnerable to problems with maintenance and repair. For example, experts say that it would take at least $15,000 to $20,000 just to repair the exterior of a complex. Additionally, the under-construction sector is not immune to the problem: according to data from the Ministry of Housing and Urban Poverty Alleviation, about 6% of all urban housing units were built without government permission between 2007 and 2012. The short lifespan of these buildings means that most residents are forced to move after only a few decades, when their mortgages become too much for them to pay. This phenomenon is known as "built out capacity" and it's one of the main reasons why house prices are so high in India's cities. Some builders have tried to address this issue by including renewal fees in their contracts, but they usually end up adding more money to the cost of construction.