There are foreigners who, in the name of a Thai family member, buy a piece of land in Thailand, and then take out a mortgage for the amount of the purchase price, in order to secure their interests. It is also possible to lease a plot of land from a Thai family member, as described above.
For more additional security a combination of both these are possible. A foreigner is, after all, permitted to own an unlimited amount of real estate, such as houses or other buildings.
In other words, a house can be in the name of a foreigner, but the land it is built on
has to be leased, with or without the added security of a mortgage, in order for this to be possible.
Foreigners with a Thai partner usually chose for possibilities enabling them to place the land the name of the partner. Afterwards, extra security is given by arranging a lease agreement with their partner, and registering this at the land registry office.
Apart from the instant added security for the foreigner, it is also a good method of ensuring that the foreigner can normally continue to live in the house after the eventual death of the Thai partner.