Residents and rescue workers have been sifting through piles of broken concrete at the site in the eastern Huruma suburb.
Aid workers said hopes were fading of finding more survivors in the rubble of a collapsed building in Kenya's capital on Monday, as the death toll reached 21.
Police said they were questioning the owner of the six-storey residential block that collapsed late on Friday after days of heavy rain and floods, but no one had been charged.
Residents and rescue workers have been sifting through piles of broken concrete at the site in the eastern Huruma suburb ever since, rescuing 135 people, according to the latest police figures.
But conditions were getting more challenging, Kenya Red Cross told Reuters.
"In conditions of no air, dirt, no food, no water, it's very difficult for that person to stay alive," Red Cross official Anthony Mwangi said.
Authorities had condemned the 198-room building and there has been no official explanation of why it remained occupied.
Government critics say corruption is rampant and real estate developers often violate construction codes to minimise costs, with little or no penalties from authorities.
-Reuters