greenboard

Q: Faucets leaked in my son-in-law’s tiled bathtub enclosure, which caused the old greenboard below them to dissolve and a few rows of tiles to come loose.

If you try to remove several rows of tile and cut away the crumbly greenboard behind them, you’ll probably find that the loose tiles aren’t neatly arranged in rows.

But to seal the joint between the greenboard you’d leave and the strip of cement board that you’d add underneath, you would need an exposed strip of greenboard — with its paper covering intact — at least once inch wide.

You should be able to remove tile and greenboard from all three walls in one day, and maybe even prep for new tiles the same day if you’ve shopped ahead of time for materials, including backer board, fasteners, fiberglass mesh tape and thin-set mortar or another waterproofing filler for joints.

Greenboard, advertised as a water-resistant type of drywall, has a gypsum core between two sheets of paper, just like regular drywall.