Akon Sued -- Mansion Floors Don't Come Cheap ... Pay Up, Man!

Akon's Georgia mansion continues to be a thorn in his side ... as yet another contractor is claiming he didn't get paid for working on the superstar producer and singer's floors.

A company called Capital Floors has filed a $15,000 lien against the troublesome home -- small potatoes compared to the $36,765 filed by a different company back in January.

This contractor claims they did get paid a little along the way and the $15k represents the unpaid balance -- but says a lawsuit for another $50k in damages could be in the offing.