The Public Servants Association (PSA) told The Times on Monday that it was "strange" that the 10 officials due to face disciplinary inquiries because of the Nkandla debacle are first offenders.
The High Court in Pietermaritzburg previously ruled that the officials' disciplinary hearings would be made public with the media allowed to attend. They are due to start on Monday.
PSA's KwaZulu-Natal manager, Claude Naiker, told The times that the officials all had "spotless" track records.
"They have been on the bid evaluation committee for a number of years, performing these duties, not only on Nkandla but on every other project involving the department. None of these employees has been charged previously for any other misconduct. Why on this project were people charged?"
Public works chief director of legal services Barnie Ntlou confirmed to The Times that one official had pleaded guilty to the charges against him and was suspended without pay. Another official died in a car crash.
Those who remain are "broadly" charged with not following the correct procedures when appointing the contractors who worked on the upgrades to President Jacob Zuma's Nkandla residence, he told the paper.
The Sunday Times reported this week that a fresh round of upgrades to the president's home are due to begin. The upgrades are reportedly to refurbish work that was previously not done properly and to security aspects of the compound.
But this week, Zuma denied any knowledge of the upgrades.
Presidency spokesperson, Bongani Ngqulunga told The Times: "There are no renovations of the private houses at the president's residence at Nkandla currently and no department has mentioned anything regarding renovations. President Zuma will not allow any government department, including the Department of Public Works, to renovate any of his private houses."
However, Tlou confirmed to the Sunday Times that the upgrades would go ahead.
"We are forced to do that. We can't allow a presidential residence to be dilapidated," he reportedly said.
And newly-appointed Police Minister Fikile Mbalula told the Sunday Times he had been briefed about the upgrades.
On Sunday, The Citizen reported that the Democratic Alliance (DA) had called for the upgrades to stop.
"It is shameful that a man who has single-handedly plunged our country into 'junk status' should live in palace of luxury, built and maintained with the people's money. If Jacob Zuma wants refurbishments and upgrades he must pay for it out of his own pocket," said DA leader Mmusi Maimane.Suggest a correction