A hotel destroyed in a fire had not had sprinklers fitted despite advice from fire safety officers.
The devastating fire which broke out at the Willenhall Holiday Inn, near Walsall, on Friday was found to have started accidentally in a sauna.
About 50 firefighters tackled the blaze at its height and no-one was hurt.
Holiday Inn said it required sprinklers in its buildings that are more than 25m high but said this hotel "was significantly below" that.
Regulations in England mean that only buildings built since 2007 and which are taller than 30m are required to have sprinklers fitted.
However, West Midlands Fire Service (WMFS) said it had recommended sprinklers were retro-fitted in the hotel "in line with our Fire Authority's position".
Further investigations would be carried out to "pinpoint the precise cause" of the fire, WMFS said.
"We will also be looking in detail into factors that might have contributed to the spread and scale of the fire," it added.
On Friday, the smoke from the site of the building in Wolverhampton Road West could be seen by commuters on the nearby M6 as well as being seen in Wolverhampton, Birmingham and Bromsgrove.
A spokesperson from Holiday Inn said the company was continuing to work with the franchised hotel's owners and West Midlands Fire Service on their investigation.
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