Updating Basement Bathroom

by Anonymous

The situation: basement bathroom with tiled walls. There was evidence of leaking and water damage. I started out just wanting to remove one wall where the damage was most evident and replacing the faucets and shower head. Removing the tile from the Greenboard proved to be futile, and I ended up removing all tile and Greenboard down to studs on all three sides. Only the tub remains. I bought a three piece tub surround.

1st challenge: The 3-piece tub surround was actually part of 4-piece including the tub. I had to do some modifying to have it set flush on the tub. The surround is a little large. It actually extends past the tub. It doesn't seem to be a problem, but a bit more challenging for a DIYer.

2nd Challenge: I have removed all Greenboard down to studs back to the nearest solid stud where I can tie into existing Greenboard undamaged by water.

Question: Can I run Greenboard up to the surround flange where I put the screws into the studs?

How do I seal the edges to prevent leakage and water damage? I plan on painting the walls above the shower extending to ceiling, and the ceiling.