India, July 30 -- Three years ago, when Dechen Angmo's family built a house in Leh city, the family deliberately chose the architecture generations of families in this high-altitude cold desert have trusted for centuries. The walls were made of sun-dried mud bricks and coated with mud. Cement was used only in the bathrooms. Everything else, Angmo said, followed local tradition.

But last summer, a week of unusually intense rainfall seeped through the mud roof and mud walls, damaging both the roof and parts of the earthen walls. Left with little choice, this year the family replaced the traditional roof with corrugated tin sheets.

"Besides being out of character with the local architecture, the tin roof was expensive as it cost us Rs 280,...