Big Sean Remodeling Beverly Hills Mansion Just in Time for Summer

Big Sean's got big plans to get his pad just right for summer pool parties ... and that means making sure his kitchen's on point, too.

The rapper's obtained a building permit for his 7-bed, 8-bath, 11,000 sq. ft. Beverly Hills mansion -- which was formerly Slash's -- to remove and enlarge the window facing the swimming pool ... according to L.A. City docs.

There's also a permit for Sean's home to re-plaster the pool and add some new lighting.

But Big Sean's biggest project -- according to the docs -- is pumping around $22k into a remodeling job to his kitchen and bathroom.