When building a new house we give priorties to things which would be helpful in protecting our house from all the ways. As well as there would be peace in the house. It is believed According to the assumptions that under the ground is hell whose king is the lord Sheshnaag. Mythological texts illustrate that the whole earth is pinned on Sheshnaag’s hood.
शेषं चाकल्पयद्देवमनन्तं विश्वरूपिणम्।
यो धारयति भूतानि धरां चेमां सपर्वताम्।।
These Paramadeva Devswrup produced Vshwarup Anant called Sheshnaag which is purportedly holding the earth with mountains. In the 10th chapter of Shrimad Bhagwat’s one shlok it is stated that, Lord Krishna said, “अनन्तच्चास्मि नागनां” meaning I am the sheshnaag among all the snakes.
Complete ritual of foundation worship is based on a psychological trust . Accordingly Sheshnag you are holding the earth on its hood. Similarly, the base of my this new house should be established on this worshipped silver snake’s hood.
That is why keeping curd, milk, ghee in a pot and chanting mantras sheshnaag is called up so that he can protect the house. The urn placed in the foundation is offered a coin as Lakshmi and is offered flowers and milk. Which are beloved by the snakes.