The fire that broke out at around 11pm is alleged to have been caused by an electrical fault.
Salat and his family were not in at the time and no injuries were reported.
Eye witnesses said the housekeeper managed to call neighbours who assisted in containing the fire.
"The fire would have blown up cars that were in the parking lot, including a Range Rover, but efforts from neighbours prevented this," the witness said.
Fire fighters arrived at the scene an hour later.
Kericho police boss said they were investigating the incident to establish the cause.
Salat has in the past been "shopping for other partners" to merge with Kanu ahead of the 2017 general elections.
In April, the Kanu secretary general said they were "still with Jubilee" but was "not ruling out the possibility of a coalition with Cord or other parties".
More recently, he has been vocal about joining the National Super Alliance, which hopes to unseat the Jubilee administration next year.