Guests were evacuated after part of the swimming pool ceiling collapsed at the Legoland Hotel, in Winkfield Road.
A lifeguard at the resort spotted a crack in the suspended ceiling at around 4.15pm on Saturday.
A Legoland Windsor spokeswoman said the building was evacuated and the fire service was called as part of the hotel's procedure to account for every person.
Firefighters from Windsor and Slough attended as well as ambulance crews and police.
The spokeswoman said: "We have apologised unreservedly to the guests and 18 rooms above the pool area were moved for noise reasons.
"They all seem happy."
Guests were allowed back into the hotel by 6.30pm and the pool is now closed for maintenance.