How To Avoid Ugly White Mineral Deposits On Shower Floors

Ugly white mineral deposits on shower floors can drive you nuts, because they can’t be cleaned away and they look like moldy leprosy on your shower floor!

This is how to avoid these moldy looking uglies in the first place, and the best way to remove them or minimize them if you already have them.
To get a background on what causes them, see this link to the earlier post on these deposits:

WHAT CAUSES MINERAL DEPOSITS ON SHOWER FLOORS IN BOSTON AREA

This ugly stuff is caused, basically, by a constantly soaked cement bed under the tile on the floor, thanks to the copper pan construction used overwhelmingly in the Boston area. By the way, this flat bottomed method of building shower pans with no weepholes to drain out this water is not the only or the preferred method of construction in other parts of this country or the world. Many places have a double mud job system that requires a pre-sloped mud job that allows the pan to be at an angle, leading to a series of small holes at the bottom that allow the water to drain out quickly after a shower so this ugly stuff doesn’t form on your shower floor. There are also systems such as the Schluter system that place the shower pan liner on top of the mud job so the mud never gets wet. These are also legal in Massachusetts, so technically you shouldn’t have to deal with the issue at all.

But plumbers aren’t usually all that interested in what’s new on the market place. Many that I’ve met are not interested in anything developed after the year 1970. They literally believe that since copper is a metal, that means it’s superior to every other material. (Even though it’s banned in some jurisdictions outside of Massachusetts!) Maybe I’m being too hard on plumbers….but their focus is usually on avoiding leaks, not appearance for years to come.

So most often when we install a shower, the copper pan has already been put in place…too late to change course at that point. Or a renovation shows a perfectly re-usable copper pan and the owner doesn’t want to pay for removing the old pan and wants the project to keep moving forward. Is there any way to build a tile shower using copper pan technology that will avoid this problem down the road?

Yes, there is.

We use the same materials for waterproofing that are commonly available to tile installers and take a few extra steps. This is no patented method; it can’t be because it’s too darn simple and makes too much sense! Instead, this is just a reaction to seeing homeowners look angry and frustrated six months or six years after the construction when they see ugliness that they never asked for.

Here are the steps:

1. When the mud job is built, add liquid latex instead of just water. This makes the mud a bit harder to work with, but much stronger when done. It also reduces the porosity of the cement somewhat, although not enough to solve the whole problem.
2. Install the cement board all way down into and inside the mud job. One common way to try to avoid wicking issues is to hang the board a bit suspended away from the mud job by half an inch or so, but in this case we want them firmly touching so they form the corner of our new ‘second shower pan liner’
3. Just in case there’s any moisture vapor that could damage the wood studs, cut strips of roofing paper and nail them onto the wood before screwing the cement board. This won’t stop all water vapor from coming out the back, just from getting the wood itself wet. We’re not wrapping the whole wall as if it were a vapor barrier, just 2” strips to cover the studs. I hate moldy wood.
4. Once the mud job is done and the cement board hung, cover both the floor and the walls with waterproofing compound. There are many brands that work and integrate with thinset cement – all of them work well. Some well known brands include Kerdi and Redgard and Hydroban. Understand that these products are typically used as shower pan liner materials all by themselves, with no copper pan ‘backup system’ below them. But our goal in this case is not to use them as a shower pan; we’re mainly trying to prevent water from saturating the mud job and the resulting efflorescence from ruining the look of the shower floor in the future. It’s cosmetic in that way, but a side benefit of the cosmetic advantage is we’re also reducing the possibilities of any leaking big time. Not a bad fringe benefit!
5. Now, you’ve basically created a second ‘shower pan liner’ on top of the copper pan liner. This one is larger since it goes all the way up the walls. Kinda like having a belt AND suspenders just to be sure.
Make sure to use premium thinset when installing the tile, the good stuff. It’s denser and has more latex polymers than the $6 per bag stuff.
6. It’s important we don’t use regular porous cement grout for the shower floor. Even with extra latex added, it’s just too porous and our goal here is to avoid water going anywhere but down the drain. Instead use epoxy grout. These are more difficult to use and are definitely not first time do it yourself category of grouts, but they have the advantage of being very watertight. We’ve used many different brands and they all work well. Just choose one that has a color you want and expect to pay extra for the product itself (it is not cheap) and the extra labor for the floor grouting (but we’re not talking a fortune on the labor side)
7. Since the walls are not epoxy grout, (they usually need unsanded grout and most all epoxy grouts are sanded) they will need a grout additive to make them more latexy too. Check the manufacturer; not all allow this. TEC has a product called Grout Boost that we’ve used a few times, but Custom Building Products, the brand sold at Home Depot says don’t use it on their grout because their grout already has plenty of latex built in.
8. After the wall grout has dried a few days, a couple coats of clear penetrating sealer is the final step. It’s not needed on the floor, since epoxy grout never needs sealer. This step will minimize water even getting through wall grout lines

At this point, your shower has been battle prepared to handle floods of incoming water without saturating the mud below the floor. Epoxy grout stops 99.3% of the water, and the waterproofing compound can handle the last 0.7% that got through. Years later when this mud job is removed, it will be dry as a bone and the homeowner will never have to deal with the yuck.

Is this approach more expensive? A little, but not as much as you’d think. It’s better practice and I hope it becomes the standard so property owners will stop being ripped off by having unavoidable ugliness sprout right in their master bath. I think losing thousands of dollars of property value is more expensive…

I know this is beyond the ability of a do-it-yourselfer. This is more a recommendation for your tile installation contractor. If you’re thinking of building a shower in Massachusetts or any other area where the plumber has ‘told you’ that you have to have a copper pan or any other flat bottomed pan approach, use the above guidelines for the tile setter to build it right so you avoid these problems down the road. And don’t expect the plumber or even most tilesetters to know this stuff in advance. Its not only rare, it’s almost unheard of to follow these steps.
If you want us to talk them through it, we’ll be glad to. Our phone number is 617-500-9271 (Eastern Standard Time) Tradespeople are often uncomfortable using new materials and don’t like the first time they try one. But all the tools and materials recommended here have a long track record of success; there are no innovations for the sake of innovations going on here.

Next post will go over how to deal with a shower floor that already has the problem.

If you do live in the Boston area and you’d like us to build the shower or just oversee the technique, you can either call or fill out our contact form below.

Towns where Boston Grout does shower building, shower repair, shower floor replacement and regrouting : Boston, Brookline, Milton, Wellesley, Newton, Weston, Wayland, Dover, Concord, Acton, Lincoln, Lexington, Bedford, Westford, Cambridge, Somerville, Arlington, Winchester, Belmont, Woburn, Waltham, Ashland, Framingham, Sherborn, Holliston, Hopkinton, Medway, Millis, Norfolk, Walpole, Norwood, Westwood, Sharon, Stoneham, Foxborough, Foxboro, Canton, Stoughton, Needham, Ashland, Chestnut Hill, Natick, Sudbury, Maynard, Stow, Watertown, Dedham, West Roxbury, Roslindale, Jamaica Plain, Randolph, Weymouth, Cohasset, Scituate, Braintree, Holbrook, Quincy, Rockland, Hanover, Hingham, Medway, Franklin, Wrentham, Medford, Malden, Everett, Revere, Charlestown, Winthrop, Chelsea, Melrose, Saugus, Peabody, Marblehead, Ipswich, Swampscott, Lynn, Wakefield, Tewksbury, Woburn, Burlington, Reading, Lynnfield, Wilmington, Middleton, Wenham, Hamilton, Essex, Manchester, Gloucester, Topsfield, Boxford, Boxborough, Boxboro, Rowley, Georgetown, Andover, North Andover, Haverhill, Carlisle, Billerica, Ayer, Harvard, Lawrence, Methuen, Salem, Beverly, Salisbury, Amesbury, Newbury, Newburyport, Harvard, Lancaster, Bolton, Franklin, Mendon, Newtonville, Hopedale and Milford.
But, what zipcodes go with those towns, you wonder…
OK, OK, here they are!
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