Engineers in Nepal are checking thousands of residential houses and apartments that were damaged during the huge earthquake last month, with about one-third surveyed so far found to be in a dangerous condition.

The engineers, on the government’s request, have already inspected some 18,000-20,000 houses in Kathmandu, said vice-president of Nepal Engineers Association, Arvind Kumar Gupta.

“We have mobilised more than one thousand engineers to check on people’s houses in Kathmandu and other cities so that we can advise them whether they are safe to live in,” he said.

The UN’s Office for the Coordination of Humanitarian Affairs put the total number of houses destroyed by the 7.8-magnitude quake at nearly 256,000, with a further 213,000 damaged.

In Kathmandu Valley more than 80,000 houses were completely or partially destroyed, according to data released by the Interior Ministry.

Many people in the capital and other built-up areas have been living in tents in open spaces after the April 25 quake, due to fear of possible collapse of their houses and aftershocks.

“This is an immediate relief. We inspect the house and tell the homeowners whether it’s safe to inhabit or not,” Gupta said.

The engineers allocate three colours, indicating the range of immediate danger – green for habitable, yellow for some repair needed, and red for dangerous or in need reconstruction.

Gupta said around one-third of those inspected received a red label.

The official death toll of those killed in the earthquake has increased to 7,675, the Interior Ministry says.