CLADDING FAILURE and lack of fire stops contributed to the severity of the massive blaze in Madrid's Torre Windsor last year, according to the official report into the disaster.
Cladding failure allowed air to feed the flames, says the report by research body Intemac.
Blazing debris also fell down the interior of the building, through service openings exposed during ongoing refurbishment.
This ignited fires on several floors.
No-one was hurt in the fire, which broke out on the 21st floor of the 28 storey city centre office block on the night of 12 February 2005 and burnt for 16 hours (NCEI March).
Partial collapse of the upper storeys occurred when unprotected steel perimeter columns failed after three hours, the report concludes.
The fire damaged all floors down to the fifth. After the blaze, the tower was demolished and a replacement is now under construction.
A major refurbishment and recladding operation was in progress when the fire broke out. As well as the service openings in the floors, much of the structure had no fire stops between the outer edges of the slabs and the cladding.
Retrofitting of fire protection had progressed no further than the 17th floor.