Rescuers are creating room to release the woman who is speaking to medics waiting to treat her, said Pius Masai, the head of the National Disaster Management Unit.
"The medical team has administered IV, glucose has been administered. She is talking and in good spirits...We are taking our time to ensure she is removed safely," Masai said.
The woman has been given oxygen and she is trapped in a small corner of her room, said Abbas Gullet, head of the Kenya Red Cross.
The death toll from the disaster has risen to 36 and 70 people are still missing, according to the Gullet.
More From This Section
A nearly six-month-old baby was rescued on Tuesday, raising hopes that more survivors would be found. The infant was found unharmed in a wash basin after the seven-storey building collapsed.
With housing in high demand in Nairobi, some unscrupulous developers bypass regulations to cut costs and maximise profits.
After eight buildings collapsed and killed 15 people, President Uhuru Kenyatta last year ordered an audit of all the country's buildings to see if they are up to code. The National Construction Authority found that 58 per cent of buildings in Nairobi are unfit for habitation. Most of Nairobi's four million people live in low-income areas or slums.