Birdman -- Borrowing $5 Mil to Pimp Out Pimp Mansion

Birdman has some big remodeling plans for his Miami mansion. How big? Try $5 million big.

TMZ obtained loan docs connected to Birdman's sick Miami mansion -- the one he bought for $14.5 million in 2012 -- and he's taking out the $5 mil against the house to do "interior remodeling" that will require construction, painting ... and lots of marble and stone work.

He's already posted renderings on Instagram of some of the work he has planned, including a shot of a $250,000 chandelier.

One last super baller part of this deal -- Birdman has ONE YEAR to repay the loan. Enjoy your 30 year mortgage!