The secretary of the National Building Inspectorate, Moses Nyakiongora, has termed the Precious Talent Academy school building “a structural failure and a work of quackery”.
In a phone interview with the Star, Nyakiongora said the second storey did not have any support.
The floors of the classrooms he said were made of wood.
"We did not see any support. The slab was poorly done with materials that resembled chicken wire and poor concrete mix," Nyakiongora said.
He criticised the school owner for building a death trap.
Nyakiongora admitted NIB officers were not aware of the existence of the building.
"The owner of the school is liable for serious negligence. He did not do necessary tests before putting up the storeyed building. He was looking to settle the surplus population."
The school has 800 pupils.
There was only one stone block in the compound.
"I cannot really say much by the time we got there the remnants had removed all materials and debris we could carry for further tests,"the NIB secretary said.
On Monday morning, eight pupils died after a classroom collapsed on them at the Precious Talent School in Nairobi.
St John's Ambulance Communications manager Fred Majiwa said the tragedy left 59 other pupils injured and admitted at the Kenyatta National Hospital.
The two-storey building made of iron sheets and wood collapsed several minutes to 7am.
Evanson Kamuri, the chief executive of the Kenyatta National Hospital, said two of the injured children were in critical condition, while others had soft tissue injuries or light wounds and were being examined.
Many of the parents and relatives rushed to the hospital.
"I had just dropped my son to school, and heard screams on my way back, and that is when I found people assisting them out to hospital," Margaret Muthoni, whose four-year-old son was injured said.
"I am just lucky my son survived with injuries. It is a very unfortunate incident because some children have died," Muthoni added.
Kepha Otieno lost his five-year-old daughter to the tragedy.
"I just can't believe. It is too hard for me and the family," he said.
Five hours after the tragedy, Education CS George Magoha closed Precious Talent Primary for four days.
