Prefabricated Houses are designed to be mass manufactured off-site in advance, in a modular form, and erected on-site quickly.
This type of building was extensively used in the United Kingdom and mainland Europe just after the end of World War 2 to alleviate the severe housing shortage caused by war damage.
Even today in the United Kingdom (70 years after their first use) many of this type of house built then are still extant and occupied.
61.88 per tile and hour 
It should be noted that this is superior to the later Suburban House (which is also 4x3) in about every way. It takes less to build a Prefab House (174,900 vs 209,900 supplies), which generates more gold (17,820 vs 7,320), and takes a little over half the time to build (4:50h vs 9:10h)