The Malay word rumah as in rumah sakit (hospital) seems to bear some similarity to the Thai word โรง as in โรงพยาบาล (rohng M pa L ya M ban M).
While in Malaysia, I've seen rumah which means house used as the first word on the sign to a couple of housing estates as well as it's being used in the word for a guest house: rumah tumpangan. Most recently I've seen it used in rumah api - the Malay word for light house.
โรง which means hall is also used in other words such as: โรงอาหาร (rohng M aa M haan R) cafeteria, or literally food hall; โรงเรียน (rohng M rian M) school, or study hall; in the case of โรงพยบาล hospital, it means nurse hall. For a complete list of the uses of โรง follow this link.