Putting up tile over sheetrock.....

[Dennis Peacock]

I have 2 bathrooms in my home. They both have the run-of-the-mill tub/shower enclosures in them (fiberglass tub/shower combos) and are single piece units. What The LOML wants me to do is to put up a nice tile and grout over the top of each tub/shower enclosure. These surfaces are painted sheetrock. I didn't build this house so I don't know if it has the typical "green or blue" drywall installed or if they cheaped out and put up standard drywall.

My question is this: Can I put up tile over the painted sheetrock/dryall?
I don't want to have to rip out all the drywall from over and around each tub/shower enclosure but hope it's as easy as roughing up the painted surface above each enclosure, putting down a mastic / thinset, apply tile, let dry, then grout.
I'm not a tile guy but I know it's not all that hard for someone like me who's done a little of everything construction related. :)

Advice, tips, pointers welcomed.

[Dave Zellers]

It would be fine but don't use thinset- use mastic.

Proper grouting is the key- pack it in tight so ALL spaces are filled.

[George Bokros]

Why not just put up cement board over the drywall then put up the tile with thinset? Don't rip anything out.

[Ken Fitzgerald]

Also, plan on resealing that grout on a regular basis as advised by the grout sealer manufacturer or use one of the new single component grouts that don't require sealing. While the single component grouts like Customer Fusion Pro are a little finickier to install, as advertised, it's water proof. I used some to retile a bathroom countertop and it works well.

[Sam Murdoch]

It would be fine but don't use thinset- use mastic.

Proper grouting is the key- pack it in tight so ALL spaces are filled.

^ This will work. I have removed 20 + year old tiles simply adhered to plain old sheetrock on 4 walls of a bathroom including behind the toilet and over the sinks (more than once) and they were still holding on fine. I wouldn't use 8x8 tiles (6x6 might be pushing it too) but smaller will be fine.

Good idea to use a grout additive rather than water. One product called Grout Boost works well. Will add an extra level of impermeability and mold proof.

[George Bokros]

If those showers/tubs were installed when the house was built it is likely there is no sheetrock behind them. They are installed before the drywall ins hung and it hung over the nailing flanges.

[Lee Schierer]

I wouldn't recommend it. Tile grout can leak water through it and the dry wall will get wet and mold will grow. I would recommend you tear out the drywall and seal the walls properly with either the liquid water sealant or install the Kerdi waterproof membrane. That will give you a flat surface to put your tile on without worries that water will get into the wall and structure. You may also need to replace the faucets and shower diverter so they will reach through the added thickness of the tile.

[Sam Murdoch]

You guys are making me doubt that I understand the OP's question:

My answer above was based on this qualifier from the OP - "What The LOML wants me to do is to put up a nice tile and grout over the top of each tub/shower enclosure. These surfaces are painted sheetrock." I most definitely would not tile a shower wall over drywall, rather than more appropriate tile substrates. BUT - over the shower section - maybe 18" of space - all out of any direct water contact - I would have no reservations to do tile/mastic over drywall.

[Ole Anderson]

When you say "over the top" you mean above the fiberglass enclosure, an area not subject to splashing? If so then you should be good to just use mastic over drywall. Otherwise use cement board under the tile. Assume water will penetrate the tile/grout if subject to splashing.

[Art Mann]

The blue or green "waterproof" drywall will definitely postpone failure by a year or two. If you want it to last 30 years, investigate the Schluter system.

[Mike Hollingsworth]

Epoxy Grout. (not easy)
Whistle all the way home.

[John K Jordan]

Dennis,

Just yesterday we had a new shower professionally prepped by a tile guy with the reputation of being one of the best in the area. Anywhere that could get direct spray or splashing he installed a composite concrete board with continuous waterproof membrane glued on top - the tile will be fastened directly to this membrane. Areas up high that had the original sheetrock (from 7.5 to 10' - this is a timber frame house with vaulted ceilings) didn't get this membrane. He said the membrane wasn't needed when the only reasonable moisture would be from steam and humidity. I believe he plans to tile directly over the intact original painted sheetrock in that area. Any place the sheetrock had been cut for plumbing was covered with the membrane.

The membrane is made in Germany. There may be guidelines on he web site - it has this printing (plus a bunch of ANSI and other codes and numbers I didn't copy):
Schlüter-KERDI www.schlueter-systems.com

If you want I could ask him what he recommends on when he does the tiling next week.

JKJ

[Dennis Peacock]

When you say "over the top" you mean above the fiberglass enclosure, an area not subject to splashing? If so then you should be good to just use mastic over drywall. Otherwise use cement board under the tile. Assume water will penetrate the tile/grout if subject to splashing.

Correct.....it would be tile from the TOP of the fiberglass tub/shower enclosure to the ceiling....about 18" or a bit less. No water gets there on purpose, steam mostly. We are even considering the removal of the entire tub/shower enclosure and installing a full large sized tile shower. Kind of like this one we had done when we added on to our house to move my MIL in with us:

379733

[Bruce Wrenn]

Before even thinking about tile, look carefully at the corners. Most likely your builder didn't shim out the wall to match the thickness of the fiberglass of the tub enclosure. This means the corners are most likely tapered, which isn't so noticable when painted. but with tile it's a different story. The complete shower system (pan, 3 walls,) from HD Supply is around $800. (HD Supply isn't Home Depot, FYI.

[Jim Becker]

Correct.....it would be tile from the TOP of the fiberglass tub/shower enclosure to the ceiling....about 18" or a bit less. No water gets there on purpose, steam mostly. We are even considering the removal of the entire tub/shower enclosure and installing a full large sized tile shower. Kind of like this one we had done when we added on to our house to move my MIL in with us:

379733

Unless you or your other half actually likes to take baths, a "real shower" is absolutely worth the effort, IMHO. When we built our addition, that's the path we took and it was the right choice. (I don't remember if you got the full tour or not) The real key to putting in a full tiled shower is the base construction. You'll want to choose a pre-made commercial composite pan or a full, built-up "mortar" base. The former is easier and faster for DIY; the latter is, well, "more rock solid" and more flexible with drain location and type. (I've become a fan of slot-drains, even though none of our showers have them) The other benefit of the built-up base is that it can be constructed to be rim-less or almost rim-less for easier access over time, depending on the space available for the shower.

To your original question and with your clarification, I don't believe you'd have any problem installing tile above the current surround as long as you use the correct adhesive. That's not an area that gets "direct" moisture. It's mostly condensation and if you grout properly, there should be no issues.

[Art Mann]

If someone counts on the grout to seal their shower (I wouldn't), then they absolutely must seal the grout properly before use and again and again according to the directions on the bag. I have seen too many shower failures to trust grout alone.

[Peter Kelly]

Epoxy Grout. (not easy)
Whistle all the way home.I wouldn't recommend anyone without lots of previous experience try to use this stuff. Epoxy grout is super tough but extremely unforgiving.

[Peter Kelly]

You'll want to choose a pre-made commercial composite pan or a full, built-up "mortar" base. The former is easier and faster for DIY; the latter is, well, "more rock solid" and more flexible with drain location and type. (I've become a fan of slot-drains, even though none of our showers have them) The other benefit of the built-up base is that it can be constructed to be rim-less or almost rim-less for easier access over time, depending on the space available for the shower.The Kerdi system by Schluter has largely replaced the old school mud bases for showers. Available as parts for custom sizes and prefabricated pans: https://www.schluter.com/schluter-us/en_US/Shower-System/Prefabricated-Substrates/c/SS-PS

Also, the Kerdi system is meant to be installed over green/blue board or (preferably) cement board: https://sccpublic.s3-external-1.amazonaws.com/sys-master/images/hf5/h6c/8858726531102/Shower%20System%20Installation%20Handbook.pdf

I've done a few showers with this, no leaks after several years usage.

[Art Mann]

That is 3 votes for the Schluter system (if I counted correctly).

[Jim Becker]

Thanks, Peter...I wasn't aware of that Schluter product. Good to know should I ever have to do another shower...which I hope not!

[Myk Rian]

You guys are making me doubt that I understand the OP's question:
Yes. It did seem to be totally mis-understood.