the meaning of the word once

[singforme]

Hi there!
I am having some trouble trying to figure out the real difference between these two sentences.

This is the house that my parents once built.
This is the house that my parents built once.

How does the once really change the meaning of these two sentences?
In the first, I understand it to be that one time, a long time ago, the parents built this house. However, I do not know the meaning of it in the second one!

Many thanks!

[knowable]

I think the writer of second sentence intended the meaning to be the same as that of first sentence – that the parents built the house at some time in the past. But, because of the position of the adverb 'once' in second sentence, the meaning of the sentence is not clear. It does not make sense logically because it suggests the parents built the house one time.

[Linguistics]

The scond sentence mean the parents just once time in all there life they built one home no more one home thanks