The Spirit House.
National traditions are usually based on mysticism and the idea that the supernatural has power over man and can bring good or bad effect on man. These are both good and bad beings: the good originally called Phee Fa or celestial bings, later called devada from the Indian term. The bad are the devils and are most feared.
Another type of being apart from the above is the being that lives with nature in forests and mountains, caves, water, trees or even in towns. They are considered the master or chao of their dwelling place. They are the guardian spirits of these places.
During ceremonies on the occasions of house building, birth, marriage, and death, Thais used to set up temporay shrines to worship the spirits and to ask for protection. Its continuity led to the erection of a permanent shrine. The spirit that dwells in this shrine is called Phra Phum Chao Thee (guardian spirit of the village). Ban in this sense refers to village since Thais usually live in a community style with their extened families.
Their are nine individual guardian spirits: Protector of the House, Protector of the Gates and Stairways, Protector of the Bridal Chamber, Protector of Animals, Protector of Storehouses and Barns, Protector of Fields and Paddies, Protector of Orchards and Gardens, Protector of the Terraces, and Protector of Temples and Religious Establishments. They are all in fact related.
The only permanent shrines are those erected for the Protector of the House and the Gardens, while others are temporary. The shrine of the Garden Deity is similar to the House Deity except that it is built a distance from the house. Temples do not require a shrine because the temple itselt is a holy place, protected by the religion, so a guardian spirit is not necessary.
The erection of a shrine must be done by a specialist. The guardian spirit whose shrine has not been set up according to the requirements, such as in the shadow of the house, will not give his protection. In addition offerings must be made annually, usually at the new year or Songkran Day (formerly Thai Traditional new year which falls on April 13, now it's the annual water festival). The offerings are placed in a banana leaf container. This is called "bat phlee". It is then placed on a tray made of banana trunk. Offerings preferred by the guardian spirit are pig's head and chicken.
In the shrine is a figure of a deity with a dagger or a book in one hand, and a horse-whip in the other. According to Chinese beliefs, the book signified the human record.
Originally, the shrines resembled the typical Thai-style wooden house with elevated floor and deep slanting roofs, varying in size. In the country, each village would have one shrine, usually some distance away, instead of one for each house as you see in Bangkok nowadays.
The shrine has greatly evolved from the past, and varies according to technique, materials, design and financial situation. Cement is used instead of wood, and they are made from molds as mass production. The size and decorative beauty vary according to one's purse string, and can be found everywhere from small houses to mansions and buildings
The Thais' belief in guardian spirits and shrines will long remain a part of the Thai culture. It is similar to the beliefs of the Chinese, the Balinese or other nations in Asia, differing in only the minor details.

As modern skyscrapers go up along city streets, architects are now designing not only the high-rises, but also the traditions spirit houses (san phra phum), creating sleek, contemporary versions that maintain architectural harmony.
The small shrines, looking much like miniature temples atop a pedestal, are not a Buddhist custom, as many visitors think. They're Brahmin in origin, enthusiastically adopted by the Thais many years ago and now found outside virtually every home and building in the Kingdom. By making the spirit houses more attractive than the home or building - along with offerings of flowers, incense, food and drink - the owners hope the spirits will live in the spirit house and serve as guardians, rather than move to the main structure.
Most Thai homes have small spirit houses prominently placed on a corner of their land (ideally where they will not be in the shadow of the home), while hotels and other large buildings have bigger, more grandiose versions. Some of the new ones are worth a look, boasting modern designs in glass and granite to match the highrises the spirits watch over.
Despite their modern appearance, traditions are not ignored. Brahmin priests approve the contemporary designs, so long as they don't violate old beliefs. All must have windows and one or more entrances, and be constructed on two levels. On the upper level is an image of the guardian spirit, and below are miniature people and animals representing the spirits followers.
Honoring the Post-Modern Spirit, Sawasdee Thai Magazine, Sepember 1997, P.12
Piraong Gulpisal, "The Spirit House", Kinnare Thai Airways Magazine, January 1987, P. 43-46

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