Police suspect blaze arson.
Around 50 fire crew spent 10 hours battling the fire in Cleveland Street, Birkenhead, on Wednesday night, through to yesterday morning after the blaze ripped through the unit.
Fire investigators were gathering evidence yesterday and the police are looking into the cause of the blaze.
Crews continued damping down throughout yesterday after the fire, which started in Parry and Sherlock Motor Body Repairers but quickly spread to an adjoining timber store.
Birkenhead watch manager Colin Evans said: "The intensity and the sheer scale of the fire were the main problems."
Police cordoned off the road between Duke Street and Livingstone Street around the warehouse.
FIREFIGHTERS also tackled a massive blaze at a St Helens recycling plant yesterday.
Fire broke out in a refrigerated recycling machine at the unit in Cornwall Street at around 12.30am.
At its height, eight crews were dealing with the blaze. Many were still on scene early this morning.
The plant was severely damaged.
The cause of the blaze is unknown at present and an investigation was launched yesterday.