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rosborn 07-25-2009 05:59 PM

Replacing shower walls
Hello all,

I am new to the forum and a complete novice with regard to the topic that brings me to the forum - I have to strip my shower walls and install the backing board and tiles.

Here's the background. The house, a raised ranch, was built in 1973. We have lived in it since 1992. About 10 years ago tiles started falling off the shower wall. I would mix some grout and re-apply the tiles as they came off. This past winter large sections of the wall came off and rather than deal with it during the winter I simply covered the walls with visqueen. I have an opportunity in the next couple of weeks (my wife and kids will be going to Florida for a week) in which the shower won't have to be used multiple times a day. I plan on taking this time to tear the walls down and install new backing board and tiles.

What do I do? A step by step process/guide would be greatly appreciated.

For what it's worth, I am a pretty handy guy and have been able to undertake every home repair that I have attempted.

Advice/suggestions are most welcome (anything except telling me that I need to hire a professional - I can't afford that)



Nestor_Kelebay 07-25-2009 09:34 PM

I don't think you'll be able to do all the work in one week's time. You could probably do it in two weeks tho.

The first thing to do is to get:

A piece (or several pieces) of scrap carpet large enough to cover the bottom of the tub or shower. That way, hard pieces of sharp tile won't ruin the finish of the tub or shower bottom. Put the plug in the tub and tape over it with masking tape to prevent any pieces of tile from getting into the drain pipe.) Then put the carpet pieces pile side down in the tub.

Also, I have done a number of bathroom shower walls (that number being 21) in my building, and I like to use a product made by the Georgia Pacific Company called "Dens-Shield" as the tile backer rather than any of the cement board like Hardibacker or Wonderboard.

Basically, you may as well tear down the drywall holding your tile up because from what you're saying, it's in very rough shape. Don't just bash it up with a hammer and pull it off; use a studsensor tool to locate the edges of the studs that drywall is attached to and cut the drywall along the edge of the stud. Then, attach a 2X2 to the side of that stud to form a mounting surface for attaching the tile backer board.

If this is an exterior wall, you'll need to replace and wet insulation in the walls, and if it were me, I would staple a vapour barrier to the studs before putting up the Dens-Shield. The grey surface on the wet side of the Dens-Shield will act as a vapour barrier, and people say not to use two vapour barriers because if moisture ever gets between them, it'll never evaporate, but the interior of Dens-Shield is a specially treated gypsum that repels water. You can soak keep that stuff underwater (as I did) for a week, and only the edges of the Dens-Shield will have gotten wet; the interior will be bone dry.

So, I'd take out the old drywall with ceramic tile attached, replace any wet insulation (and you may find some rotted wood), put up 2X2's to act as nailer on some of the studs (flush with the surface of the stud) and put your Dens-Shield panels up.

Don't run the Dens-shield (or any other tile backer panel) over the lip of the tub. Install the panels so that their bottoms are 1/4 inch above the top of the lip of the tub. Some people fill in the gap under the panels with caulk and stuff, but I've always just used large enough tiles that they hung down over that gap, and that works fine too.

Then, one trick I like to use is to mark a horizontal line around the tub area on the Dens-Shield that's almost the height of the ceramic tile you intend to use. Now, use some double sided mounting tape to stick a STRAIGHT piece of wood molding onto the wall so that the top of the wood molding is level with that line. Now mark vertical lines along the walls so that if you set a tile with one edge along that vertical line, the tile at the end of the row (that goes into the corner) will have to be cut a bit to fit. That is, you want to be cutting the tiles that fit into the corners at the front and back of the tub because the walls might not be plumb or vertical. If the wall bends a bit or isn't straight, then you may have the walls diverging from the tiles, in which case you end up filling a gap with grout. It's much better to have 90 percent of a tile there so if the walls aren't straight, you can cut the tiles a bit wider or a bit narrower, and the tiling will still look good.

So, you set your first course of tiles on that wooden molding first and give them a chance to set up. Then you set the rest of the tiles above the first course. Then you remove the wood molding and CUT the bottom course of tiles to fit down to the tub. That way if the tub isn't level and leans to one side or the other, you can still cut the tiles to fit down to the tub. That way, even if your tub is installed crooked and your walls are out of whack, you can still install the tiles straight by installing the first course on that horizontal wooden molding.

I like to use those small plastic "+" shaped spacers to put the tiles up with. Despite their shape, DO NOT put them flat against the wall like the tiles and try to pry them out later. Put 8 in around each tile and insert them PERPENDICULAR to the tiles so they can be pulled out once your mastic or thin set cures.

My computer's been crashing lately, so I'm gonna post now before I loose it.

Nestor_Kelebay 07-25-2009 09:59 PM

Also, when cutting the tiles for the corners, DON'T try to get the tiles to fit perfectly at the corners. That won't give the grout you'll be putting into the corners anything to grab onto. Cut the tiles so that there's a 1/8 inch gap or so at the end of the tile to give the grout you put in the corners something to grab onto. But, the tiles that are cut to fit down to the tub should be cut to come quite close to the tub. Try to leave about 1/32nd of an inch or so between those tiles and the tub if you can.

And, I've found that you can avoid grout maintenance problems the most by using relatively large tiles (like 6 inch wide by 8 inch high tiles). That is, you minimize grout problems by using large tiles to minimize the amount of grout you have to seal.

The basic procedure when grouting is to mix the grout THICK and let it sit for about 5 to 10 minutes. Cement based grout is "thixoplastic", which means it stiffens when it sits there, but thins right out once you start to work it. So, after mixing the grout, it will stiffen up during the 5 or 10 minutes that you let it sit there (pronounced "slake"). Then, mix it again, and it'll thin right out again, and you can start grouting.

Notes on grouting:

Before you start grouting, use some masking tape to mask off the gap between the bottoms of the bottom course of tiles and the tub. It's OK if grout gets into the bottoms of the vertical grout joints just above the tub, but you'll be caulking between the bottoms of the tiles and the tub, and grout getting into that bottom gap is going to leave open the possiblity of you're getting hairline cracks in the glazed surface of the tile due to pressure put on the bottom tiles by the house moving. You want to have any gap between the bottom edge of the tiles and the tub caulked with soft silicone caulk rather than have hard grout in there.

1. You will need a special tool to grout the tiles in between the faucet knobs and tub spout. Buy a "margin trowel" and put masking tape or duct tape on the blade (to avoid marking the tiles) and use that to grout in tight places like that.

2. Don't mix up more than about 2 cups of grout at a time. It'll take a fair bit of time to pack that grout into the grout joints, and the grout will be drying on the surface of the tile as you grout. So, it's best to grout your tiling in sections rather than grouting all the tiling and then finding out the grout is too dry to remove from the tiles with a damp sponge.

3. Keep a popsicle stick or any kind of tool that's a bit narrower than you grout joints. After packing your first 2 cups of tile into the grout joints, go around the perimeter of that area and use the popsicle stick or tool the pack the grout at the ends of the grout joints. That way if you just have a thin bridge of grout spanning the joint, that tool will reveal the joint isn't full of grout as you pack the joint at the end.

4. After packing the joints with a popsicle stick or tool, then don't start cleaning the residual grout off your tiling with a damp sponge. That's just stupid instructions they give in the How-To books that are written by people who've never tiled more than once in their life. What you do after packing the 2 cups of grout in is SCRAPE the grout joints down to a uniform depth with your popsicle stick. You just have to be careful at the corner where you can gouge out too much grout and leave a depression in the corners where grout joints meet. After all, one of the purposes of wiping the grout joints down with a wet sponge is to get them to a uniform depth. And, the easiest way of wiping your grout joints down to a uniform depth with a damps sponge is to START with them at a uniform depth!

5. After scraping the grout joints down with a popsicle stick (or whatever), now wipe the residual grout off the surface of the tiles with a damp sponge (rinsing that sponge out often). Basically, that's the easiest and most rewarding part of the job because you finally get to see what your ceramic tiling will look like. But, alas, you might find out that the grout dried on the surface of the tiles is too dried out to be removed easily with a sponge, and that might make you panic. (If that happens, you can always wet the tiles you haven't done yet with a sponge to get that grout wet, and as it absorbs the water it'll soften up again so that the grout can be more easily removed.) However, it's always a good idea to have a couple of green Scotchbrite pad handy to take that grout off the surface of the tiles real fast without scratching the glazing on the tiles. If you're concerned about scratching your tiling, then use the almost as effective white Scotchbrite pads that don't have any abrasives inpregnated into the nylon fiber the pad is made of.

Nestor_Kelebay 07-25-2009 10:11 PM

Also, always order extra tiles and keep them in the attic or basement in case you ever need to replace a cracked tile.

And, never grout around the holes for the faucets or tub spouts. Stick something (like toilet paper) into the gap for the time being until the grout has fully cured, pull the toilet paper out and caulk around those holes. Grout in those areas will crack and fall out, leaving the door open for a leak in the wall.

I RECOMMEND that you do all your tiling and grouting first, and then stick your soap dishes or corner shelves TO the surface of the tiles rather than try to incorporate those into the tiling. Incorporating them into the tiling just causes you to cut more tiles and makes the grouting harder. I have a 21 unit apartment block, and every one of my bathrooms has the soap dishes stuck to the tiling with Either GE 1700 or Dow Corning 786 silicone caulk, both of which have much better adhesive properties than less expensive silicone caulks.

Anyhow, back to grouting.

As you grout, you'll find that after about 20 to 30 minutes, the grout will start stiffening up on you. Don't mix in any more water to thin it out. This is normal if the grout hasn;t been packed into the joints be the time it "kicks". If you want to, you can try packing that stiff grout into the corners at the front and back of the tiling, but I'd avoid that because of the liklihood of not getting that grout in the corners uniform if you do it all at different times with different batches of grout. So, if your grout "kicks" on you before you've used all 2 cups, it's time to move on to the next step and start tooling and smoothing the portion of the 2 cups you did get into the grout lines.

Repeat steps 1 to 5 on the previous post in 2 cup increments until you do all the grouting. You will see a "haze" of grout form on the tiles as they dry from being.

After doing all the walls, then do the corners and edges of the tiling. People buy bullnose tiles for the edges, which I think is a waste of money. Just make a triangle shaped fillet of grout at the edges of the tiling with your rubber float and do the same thing in the corners with your fingers and it'll look fine to anyone concerned enough to be inspecting it.

Turn the fan in the bathroom on and clean up for about 2 or 3 hours while the fan removes the humidity in the air. Maybe watch TV for a few hours (but not more than 6 hours or so).

Now, go back into the bathroom and rub that haze off the tiles with a DRY cloth. Preferably a dry rough cloth, like linen or something. Don't use burlap because it'll leave all sorts of crap behind in/on the still relatively soft grout. You want the cloth to be rough to scrub the haze off the tiles, but it has to be civilized so that it doesn't leave a lot of crap behind. And, that cloth has to be dry to clean the haze off permanently.

Now, you want to pull the masking tape off at the bottom of the tiling, remove the carpets in the tub, wipe the tub out with a damp sponge, pull the masking tape off the tub drain and get some Dow 786 or GE 1700 silicone to caulk with. Give the grout several days to cure hard before caulking if you can.

Nestor_Kelebay 07-25-2009 10:50 PM

Now, ceramic tiling contractors will tell you with a straight face that you don't need to seal your cement based grout. And what they're saying isn't a complete lie. You see, grout is a cement based product and it contains lime (which is calcium hydroxide, or HO-Ca-OH) just like concrete and brick mortar. It's those hydroxide (-OH) groups in the young grout, mortar or concrete that makes these materials highly alkaline for the first few years of their life, and it's that high alkalinity that makes fresh grout an inhospitable place for mildew to grow.

But, there's something called "the lime cycle" that takes over the minute the young grout is dry enough for air to get inside it...

That lime (HO-Ca-OH) in the grout starts reacting with CO2 in the air to form limeSTONE (calcium carbonate, or CaCO3) which doesn't have a "chemical structure" because it's an ionic salt. It has ionic bonds holding it all together, not covalent bonds that use pairs of valence electrons in the outer electron shell like CO2, H2O and NH3 all do. It looks like this:

It's a crystalline structure consisting of carbon atoms, each surrounded by 3 oxygen atoms, and each such CO3 group has a Calcium atom associated with it. If you dissolve limestone in water, those CO3 groups would form carbonate (CO3--) ions and the calcium atoms would form calcium ions (Ca++).

Anyhow, the point is that as the lime cycle progresses, more and more of the HO-Ca-OH (calcium hydroxide) in the young grout reacts with the CO2 in the air and forms CaCO3 (calcium carbonate). And, as those -OH (hydroxl) groups in the grout disappear, the grout becomes less and less alkaline, and more and more habitable for mildew to grow in it.

So, you don't need to seal your grout right away, but to say you don't need to seal it (full stop) is not the complete truth. It's only the whole truth to the contractor because mildew won't start growing on the grout for at least a year, or until his warranty has expired.

It's best to NOT use the shower until you seal the grout because any soap scum you seal over will both prevent the sealer from sticking well to the grout and can provide food for mildew that CAN grow under the sealer just from water molecules that will migrate through acrylic grout sealers and any acrylic plastic for that matter. You could, however, use the shower for a year, then give it a good cleaning with a phosphoric acid based bathroom cleaner, allow it to dry overnight, and then seal the grout. Phosphoric acid is the active ingredient in many bathroom cleaners because it cuts through soap scum easily, but won't harm chrome plating. Even though it does dissolve grout, you'll be dissolving so little that it won't matter. It's more important to remove all mildew food from the grout before sealing than it is to have slightly fuller grout lines.

Here's more about the Lime cycle so you know I'm not just making all this stuff up just to screw with your head:
What is Lime? | Products | Graymont

jjm 07-26-2009 06:21 AM

Wow...I was just reading through this and learned a lot. Nestor....thanks for taking the time to respond so thoroughly. Many people will benefit from this.

rosborn 07-26-2009 07:52 AM


Thank you for the detailed response. I've copied and pasted it to Word. I will print it off and read it and will respond after having done so. My first impression is that what you have posted is the right way to do the job. I'm just curious though, is there a way to get around the tile portion of the job? In other words, is there a water proof paneling that can be utilized instead of tiling? I don't want to use one of those pre-made enclosures because the tub is fine but I am concerned about working with the tile and grout.

Thank you very much for the detailed response.


Nestor_Kelebay 07-26-2009 11:09 AM

Thanks, JJM.


If you're wanting to get everything done in one week, then I'd definitely install a tub surround instead of ceramic tile. Tub surrounds are much faster and easier to install, and they're more reliable not to leak.

Installing A Tub Surround - Popular Mechanics

I haven't read through the above article, so I don't know if I'd agree with everything that's said in it or not.

But, if it wuz me, I'd probably plan on tearing down the drywall (or whatever) that's behind your existing tiles and putting up either new drywall or Dens-Shield. Tubsurrounds are pretty reliable for not leaking, so most people won't bark at you too much for using ordinary drywall behing a tub surround. Still, I'd run the drywall down to 1/4 inch above the tub lip and have the tub surround hang down in front of the tub lip down to the tub top.

Easiest way to install them is to buy a 5 piece set (front, back, side and two corners) and have a helper hold the corner in place while you put the other two panels behind the corner piece and mark it with a felt pen. You want to have 1 1/2 inch of overlap or so between panels and corner pieces, and you want to join those pieces by putting a bead of silicone caulk between them and squeezing them together until the silicone comes oozing out from between them. Then you know you've got a full 1 1/2 inch of silicone the water would have to get through in order to leak through the joint.

These tub surround kits can cost anywhere from $100 to $1000, and one of the largest manufacturers (called "Manhattan" I think) makes some decent ones.

Easiest way to cut the panels is to score the line with a plastic laminate knife. Score repeatedly and then just bend the panel at the score line and it should break right along the line just like plastic laminate.

Use scrap cardboard to make a template for the front of your tub. Cut big holes for the faucet knobs and tub spout. Cut the correct size of hole in smaller pieces of cardboard. Slip the scrap cardboard (which you can buy for about $2 for a big piece at most stationary stores) onto the knobs and spout pipe at the front of the tub, then slip the smaller pieces on, then tape the small pieces to the large piece, and you have a template that allows you to cut the holes in the drywall (or Dens-Shield) and the front panel of the tub surround accurately so the holes line up with the plumbing. Depending on what you're lining up your cardboard with when taping those small pieces of cardboard in place, you might have to pull the tape off and do the above procedure twice; once for cutting the holes in the drywall (or Dens-Shield) and again for cutting the holes in the front panel of the tub surround.

I'd use GE 1700 or Dow Corning 786 silicone here simply because they are stronger silicones and would adhere the panels together better.

Use the search engine in this web site to search for a post by me several months ago that explained how to:
1.) properly remove silicone caulk
2.) effectively clean silicone caulk, and
3.) how to install silicone caulk so that it doesn't look like it was done by a monkey.

If you can't find that post, let me know. I've got the original on my hard drive.

rosborn 07-26-2009 11:51 AM


Thank you, once again, for such a great and informative post!

I think I'm going to go with the shower surround. Yeah, I'm definitely going to replace the drywall that's behind the tiles now. No sense in doing this and not doing it right. For what it's worth, two of the walls are interior walls (one short wall and the long wall). I have to admit that one of the reasons why I have put this off for so long is because I have been put off by having to work with ceramic tiles. I am a geologist not a mason so I was concerned that my tile job would look bad.

You are the bomb and you have given me one of the tools that I will need to do this. Thank you very much!


Nestor_Kelebay 07-26-2009 01:16 PM


Originally Posted by rosborn (Post 32636)
I have to admit that one of the reasons why I have put this off for so long is because I have been put off by having to work with ceramic tiles.

Well, anyone in your position would feel the same way. Not only are you doing something you've never done before, but you've got a very limited time to do it. In that situation, everyone would be worried about running into problems and not being able to get done on time. In you're situation, I would definitely go with a plastic tub surround.

Also, if you ever need to remove and recaulk around your tub surround, you probably won't be able to use steel razor blades to remove the old silicone caulk because they'll cut into your plastic surround. You should be aware that there are plastic razor blades you can buy which should allow you to remove silicone from plastic without damaging the plastic:

Double-Edged Plastic Razor Blades - Lee Valley Tools

Anyhow, good luck with this.

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