Go into every nook and cranny of the place, omitting not a single one. Sprinkle every corner and crack abundantly with Holy Water, also blessed with the older Rituale. If I were doing this, I would even use blessed salt around the perimeter of the whole place, the corners of the rooms, and over the floors before laying new carpet, perhaps also with medals.
In such a place, where so much evil has taken place, the clutch of the Enemy will be strong indeed.
Do not use half measures. Nuke the place.
~ Fr. John Zuhlsdorf, recommending that Bishop Earl Boyea of Lansing, Michigan, exorcise a former abortion facility that will be used as parish offices, What Does the Prayer Really Say?, August 10