Interest Cost in a long live asset existing, building, account, interest

cross-ied

Suppose a firm builds a building using a loan (debt), the interest is capitalized

But, if the firm builds a building with its own money(no debt), then interest rate on existing related borrowings are taken into account(say 5 % for example)....

Will this cost(opportunity cost of cash held) be expensed or capitalized and why?

I think it should be capitalized