But its general manager Christopher Spencer vowed this week the the club would “bounce back”.
Up to 70 firefighters tackled the blaze, which extensively damaged the B-listed Georgian neoclassical style Killermont House, built in 1805.
No one was injured but a club spokesperson has said it may take several years before the building can be restored and reopened.
Glasgow Golf Club is the ninth oldest in the world and presently has around 1,000 members.
The day after the blaze, club captain David Clifton said the overriding feeling was of “absolute devastation”.
He added: “The clubhouse is a wonderful old building with some priceless artefacts.”
These include one of six original ‘Calamity Jane’ putters used by American golfing legend Bobby Jones.
Archivist Nevin McGhee said: “It will be some time before the full extent of the damage is known.”
But he added he believed trophies and medals dating back to the early 19th Century were saved, including the Tennant Cup, one of the world’s oldest amateur stroke play events.
Scottish Fire and Rescue confirmed some historic items inside the building had been salvaged. Fire chief Thomas Sinton said: “This has undoubtedly been a challenging and protracted incident. But I would like to take this opportunity to praise the response of firefighters – they have been outstanding.
“This is one of the oldest golf courses in the world. I am very pleased to say that our crews were able to assist in salvaging some of the interiors within this historic building.”
The alarm was raised around 9.20pm on Thursday and crews worked through the night and into the following day to bring the blaze, which had taken hold within the roof space of the three-storey building, under control.
Mr Clifton praised the emergency teams, describing them as “absolutely superb”.
The club has received calls and emails from other golf clubs in Scotland offering help.
General manager Christopher Spencer tweeted on Monday: “Thank you to everyone who responded to the news of the fire at our clubhouse. No one was hurt but the clubhouse is 80% damaged. A very emotional day but lots achieved by my team. The bounce back has started!”