About 30 protesters refused to leave Pantycelyn at the end of term on Sunday and five climbed on the roof on Monday.
The campaigners said they would also go on hunger strike on 21 June, the day before a decision is due on whether the accommodation will close indefinitely.
The university recommended the halls close to make them "fit for purpose".
It said the building would still be used for Welsh language services.
But campaigners have accused the university of not placing enough value in the Welsh language.
Student Bethan Roberts said: "We are here occupying the building with students and people from all over Wales to ensure this stays as a Welsh halls of residence."

Armed officers forced a car to stop on Spring Garden Street in Ballybough at about 18:00 on Friday.
They discovered what they believe to be a quantity of detonators and Semtex explosives.
The surrounding area has been cleared and cordoned off and an army bomb disposal team is attending.
The two men are being held under Ireland's Offences against the State Act and can be questioned for up to three days.

A hardback edition of Harry Potter and the Cursed Child - Parts I & II will be released on 31 July, the day after the play has debuted on stage in London.
Following Wednesday's news, pre-orders have propelled it to number one on the Amazon and Waterstones book charts.
The play sees Harry as a father and an overworked Ministry of Magic employee.
The script is from an original new story by JK Rowling, Jack Thorne and John Tiffany.
Harry Potter and the Cursed Child will tell the "untold part" of the boy wizard's story, including the story of the lives of his murdered parents, Rowling has said.
In a statement, Waterstones said it expected pre-orders to break all records and were already exceeding those for Harper Lee's Go Set a Watchman over the comparable period.
Last year, Go Set a Watchman was the first title whose pre-orders reached the heights of those for Harry Potter and the Deathly Hallows in 2007.
James Daunt, chief executive of Waterstones, also told Radio 4's Today the "prospect of an eighth volume is extraordinarily exciting".
"I challenge the notion that plays aren't a fabulous, an extraordinary, thing to read -  that bloke Shakespeare wrote a few that were worth it, and indeed many of our modern playwrights do too.
"Because theatre is a very local phenomenon, play scripts do sell well, they just do so in the immediate locality of the theatre. They are wonderful entertainment, more people should do it."
The special rehearsal edition of the script book will comprise the version of the play early in the production's preview period and is therefore subject to being changed before the official opening.
The edition will, therefore, only be available for a limited time, said the publisher, "to be replaced by the definitive collector's edition at a later date".
David Shelley, chief executive of the publishers Little, Brown Book Group said on Wednesday: "We are so thrilled to be publishing the script of Harry Potter and the Cursed Child.
"JK Rowling and her team have received a huge number of appeals from fans who can't be in London to see the play and who would like to read the play in book format - and so we are absolutely delighted to be able to make it available for them."
The play, Harry Potter and the Cursed Child, has already proved to be a success with an initial round of  175,000 tickets sold in October within 24 hours of booking opening. Producers released a second batch, available to fans who had registered for priority booking.
A third set is still to go on sale but the date is yet to be announced.
Previews of Harry Potter and the Cursed Child begin in May at London's Palace Theatre, with both plays set to open on 30 July.
Jamie Parker, currently starring in the West End show Guys and Dolls, will star as an adult Harry in the production.
Noma Dumezweni, known for her 2006 Olivier Award-winning role in A Raisin in the Sun and for stepping in at the last minute to replace Kim Cattrall in Linda at the Royal Court, will play Hermione Granger.
London Road star Paul Thornley will play Ron Weasley.
Students at Aberystwyth University have climbed on the roof of a Welsh language hall of residence to protest its proposed closure.
[NEXT_CONCEPT]
Two men have been arrested after explosives were discovered by police investigating dissident republican activity in Dublin.
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The script from the forthcoming Harry Potter play has leapt to the top of bestseller lists, a day after its July release was announced.