'castle house' is a correct and usable phrase in written English.
You can use it when you want to refer to a house that has been built in the style of a castle. For example: The grand castle house was situated atop a hill overlooking the beach.
The Renaissance town hall and a 15th-century castle house museums.
Theresa May (St Juliana's) and Jeremy Corbyn (Castle House prep school) face off.
The couple's home in Essex, Castle House, is now a Munnings museum.
Castle House, a new four-bedroom holiday let within the 16th-century walls of Taunton Castle, has been restored for the first time in 300 years and will be available from 6 December.
Castle House was launched to provide a home for three girls, but with high levels of interest from across the country, Phoenix is considering rolling out further provision in future.
She was one of the first in New York to believe physically and financially in the fox trot, and in 1913 bought some shares in Irene and Vernon Castle's famous Castle House, of which Miss Marbury was the chief backer.
Figueres is home to one of three museum centres run by the Gala-Salvador Foundathen in the region (the others are the Gala Dali Castle House-Museum in Pubol and the Salvador Dali House-Museum in Port Lligat).
Morsbroich Castle houses a museum of modern art and is used for plays and concerts.
The four blocks in Elephant and Castle housed the then Ministry of Health for 25 years, but are now residential flats.
The Rocca, a 14th-century castle, houses the Roman and Risorgimento museums, and the old citadel has a museum of geology and natural history.
The castle houses the remains of a ship dating to about 300 bce that was recovered in 1969 approximately 0.5 mile (0.8 km) offshore.
