Designing Kitchens and Bathrooms - Disagreement: can you help?

We have a rental property we're remodeling. A friend is doing the work for us. He's a jack-of-all trades sorts and does quality work. We've hit a disagreement with the bathroom. The house is aging and the old ceramic tile was losing it's grout. Unknown to us, at some point in the past a tenant put caulk in between tiles rather than replace grout. As a result water seeped behind the tile. This became evident when the tiles buckled. So we ripped off the tile and are down to 2x4's. I wanted ceramic again, but for economic reasons we'll probably go with a tub surround.

The disagreement: I'm a big fan of rockboard, it's in both baths in our primary residence (which are tiled). Our friend insists that is not the way to go with a tub surround - he insists the surround won't adhere well to rockboard. He inists greenboard should be used strictly for tub surrounds, rockboard strictly for tile.

My primary goal here is to prevent water/wall problems down the line so we're not redoing this again at some point. Any thoughts on this? Is there any reason why rockboard would not work behind a tub surround?

Thanks!

What backing does the manufacturer of the tub surround recommend? Buy it while the walls are open to make sure everything fits and lines up (plumbing, etc).

Most of the tub wall recommend green board.

I would suggest greenboard.

Using rockboard is a sturdier product. But in this situation.....It would not match the necessity of why it is needed in this case.

Thank you for the advice, greenboard it is. I hope we can get some longevity out of it, will have to watch meticulously that the caulk remain fresh and viable and there are no areas for potential leaks. Your help is appreciated ! -Kat

Dear Kat, one small observation. You mentioned keeping the caulk fresh. I'm surprised the surround manufacturer hasn't specified using silicone to seal all the joints. Check with them before using a kitchen/bath caulk. Good luck !!!