The storage facility at the former Brickkiln site is being demolished, it has been revealed this afternoon.
According to the Northern Ireland Fire and Rescue Service, contractors have begun removing panelling at the premises at Electra Road, Maydown.
The NIFRS remain on site.
A spokesman for the NIFRS said: “Since Wednesday the fire has continued to burn out to such an extent now that it is now safe for the demolition of the building to commence.
“Demolition has begun on site today, Friday, November 13, by contractors who are removing the roof and external panels of the building. This will give Firefighters better access to the seat of the fire to continue to extinguish the fire.
“The Maydown Road has been closed and traffic management is being directed by the Police Service of Northern Ireland and the Northern Ireland Fire & Rescue Service. Motorists are advised to avoid the area as the operation is likely to continue into the weekend.
“Although the smoke plume from the fire has decreased in size, NIFRS continues to advise householders and premises in the area to keep windows and doors closed. Windy conditions remain on the weather forecast and people need to be vigilant to a change in wind direction, keeping windows and doors closed.
There are 11 fire appliances currently on site, including two high volume pumps, one aerial appliance and the command support unit.
“NIFRS are working closely with the site owners, NI Environment Agency, PSNI, Public Health Agency, Northern Ireland Electricity and Derry City & Strabane District Council in the ongoing management of this incident,” the spokesman said.
“Northern Ireland Fire & Rescue Service continues to thank the local community in the area for their understanding as Firefighters deal with this incident.
“The cause of the fire remains under investigation.”