Three units of Dublin Fire Brigade have brought another blaze at Belcamp College under control.
The second fire incident in 24 hours happened at around 5am.
The historic building, designed by the architect of the White House, was damaged yesterday by a significant blaze.
The house, which was bought by Gerry Gannon in 2004 for €105m from the Oblate religious order and subsequently taken into NAMA, has been subjected to arson attacks in the past.
Belcamp College was designed by Kilkenny-born architect James Hoban, who was responsible for the White House in Washington DC, and also featured an oval room which was gutted in a previous fire.
The house was built in the 1770s with the Oblate fathers founding the Catholic college as a boarding school in 1893.
Yesterday, An Taisce has called for Fingal County Council to move to protect the listed historic building.
An Taisce said "failure to put the building to a new use and to protect the buildings from break-ins and vandalism has caused significant damage including the gutting of the late 19th Century school adjoining the 18th Century house, which was left inadequately secured during the years of the property crash".
It said: "Fingal County Council must urgently intervene to establish the current ownership of the building and any continuing involvement of NAMA and to ensure that the roof is repaired and further damage averted".
