Is it necessary to put green board as a backing when using a fiberglass shower or fiberglass tub and shower surround?

Actually if at all possible (meaning if you haven't framed it already), I wouldn't put any backer behind the shower. I'd install the shower surround directly on the framing and then lap the sheetrock that is above the surround down over the surround, there should be a little lip at the top of your surround just for this purpose, this will prevent any water from getting behind your surround. If it is already too late, then green board can't hurt - for the sake of a few bucks, it's a little added insurance.

Part of this depends on whether your shower surround is heavy enough to stand on it's own. If it is, then I would forego the backer. If not then cetainly use green board. In fact I would use green board in the entire bathroom. An even better option may be the newer densguard (spelling?) fibreglass faced drywall. It could save you some mold issues down the road.

DensShield is better than green board
It has an acrylic based coating that prevents water/moisture from penetrating through and causing rot and mold.

and yes, install shower unit directly to studs with screws and lap over with wall board.

Don't nail the shower unit to the framing.
We did a bath remodel not long ago that the homeowner did that.
The nails will just work their ways out. Same with installing wall board, use screws.

Matt
Cupan Custom Tile and Paint
Charlotte, NC
tile contractor

I know greenboard is not necessary behind fiberglass showers, but is it necessary behind acrylic showers?

Any bathroom regardless of what type of shower your using should have at least a green board installed if you need to install any at all.
The pre-cast fiberglass units typically fasten directly onto the framing so no rock needed there. The Acrylic showers if I remember are glued onto the walls and come as kits. If this is the case you need to use a water resistant material such as green board.
We use Dens-armor sheetrock. Fiberglass face. Does not fall apart when it gets wet. And does not allow for mold growth as the material does not support it. Costs about the same as green board perhaps dollar more. But well worth it.

Hi. I accidently popped four tub wall tiles out while leaning on them cleaning. The wall board underneath had deteriorated. We don't want to retile. My question: Can we put fiberglass sheeting over the remaining tub wall tiles or do we need to worry about what's underneath the tiles and first remove all the tiles and wall board underneath before we do anything? And, IF we decide to go with the fiberglass sheeting (our tub is fine) would we need to put up new greenboard under the fiberglass (assuming tile and wall board removal were necessary)? We are also considering a silestone tub wall. Thanks for any information you can provide.

Water has made its way under the tile. This is why the material behind the ones that came off were damaged.

You cannot simply cover over the bad spots with new material Regardless of what you want to use.
I assume when you say fiberglass you mean Formica like they use on counters? Regardless of what is used you must first remove the damage area. I do not suggest that you cover over the good tiles. Its not professional, It will take more work to properly finish the edges and you will simply cover over what is most likely mold that has begun to develop.

In addition. Every time my company does a bathroom tile repair. Assuming the bathtub/shower is older. We remove the faucets and replace with new. As luck will have it once everything is done and cleaned up the old faucets tend to leak, or need some sort of repair and the wall needs to come down again. You may spend a few hundred dollars more but knowing everything is done correct is good piece of mind.

Thank you for your response. I pulled off more tiles today to "see" what was going on underneath. It looks like concrete (?) backboard which is cracked and in some places deteriorated to course sand. We will replace everything. I appreciate the advice.