A portion of the roof in the Mater Hospital was also damaged. A small number of patients in the Mater Hospital were temporarily assigned to other beds.
Heavy rain caused flooding across parts of Dublin city and Co Cork last night.
The Dublin Fire Brigade has said a section of Portland Lock along the Royal canal in Dublin collapsed.
It also reported flooding on Church Street and St Bridget's terrace in Oldcastle Co Meath.
Extensive damage was caused to some shops and houses on Main Street in Midleton and in the Ballinacurra area.
DART services are suspended between Bray and Greystones due to lightning damage to overhead lines.
Dublin Bus will accept rail tickets to and from Greystones.
Elsewhere, hundreds of homes in Cork and Wicklow were left without power.