Ugly peeling mastic on back of tile

The ugly peeling mastic on the back of this tile came from a shower that was less than 2 years old. It was bulging and grout lines were cracking from the damp swollen sheetrock behind the tile.  Black mold was growing also, which was a concern to the upset homeowner.  This shower could have lasted a century if thinset cement was used instead. The total replacement that was necessary cost the homeowner totally unnecessary money, money she had already spent once and now had to spend again.

If mastic is so evil, why would anyone use the stuff anymore?

To recap earlier posts, mastic is a tile adhesive used to hold up tile on vertical surfaces like walls. But in a shower, it weakens over time as the moisture from the shower makes its way to the back of the tile. This leads to a LOT of tile failures and the need for tile repair.

If tile repair were cheap and easy, it wouldn’t be much of an issue…but it’s not so easy and cheap.

So, why is mastic still sold?

It’s very easy to use. It is sticky, so it grabs wall tile and won’t allow it to slide down the wall. The better material, thinset cement, doesn’t have instant grab. Instead, you have to actually build a small support of the wall tile so they don’t slide down and fall off while the cement is wet. This is called a batten board, and it takes maybe 10 minutes to put one on the wall. So if the shower has 3 walls, it might take a total of 30 extra minutes to tile the shower. Maybe a bit more, counting the time to mix the thinset, but not much more. So for half an hour’s savings, tilesetters make your showers ‘guaranteed to fail’. Ridiculous!

The only legitimate use for mastic is on a wall surface that you know will never get wet!

Outside a shower, you might use it for bathroom walls or kitchen walls. For backsplashes, I’d still be nervous if the sink splashed near the wall tile. I’ve even seen some backsplashes ruined by mastic installation.
Fireplaces? Nope! Mastic also weakens during exposure to heat as well, not just water.

So, to summarize, the stuff is only useful if you know the tile will never get wet, or hot, which kind of rules out almost every tile installation I can think of.

Just say no to the stuff….say yes to real thinset cement!

Related posts

• Why You Don’t Want Mastic In Your Tile Shower Unless You Want Tile Repair Bills! (0)

How should we answer?

Something on the order of “NO, NO, NO!!!!!!!!!!!!!!!!”

Bear in mind, this is in very nice house easily worth millions in a very nice neighborhood and they had recently finished a $60,000 renovation. Maybe the contractor would use premium materials, just maybe?? Maybe he’d hire a tilesetter who knows what to use and what not to use? Just maybe?

It gets us mad when tilesetters who are supposed to know their trade use a material that creates this sort of problem. It’s the same material, time after time. It should be outlawed, in my opinion, or at least have huge warning labels all over the bucket.

What is this nasty, shower-destroying, money burning, evil stuff called?

Mastic. It also uses the alias ‘pre-mixed thinset’.

What’s so bad about it?

Simple. It’s not real cement – it has more in common with glue. And it’s water sensitive. Meaning that over time when water seeps through the grout lines, the mastic gets weaker and weaker and the bond between the tile and wall gets looser and looser. At some point, you can actually have tile fall off the wall or pull them off yourself using your hand. Make no mistake, water always get through grout lines.

This is true even if the tiler used real cement board walls. Glue just can’t handle the amount of moisture that showers create. If it’s a steam shower, it’s doubtful the shower might even last a few months of normal use.

How can you recognize this evil compound? Simple: it comes all premixed up for your convenience in a tub or bucket and you just scoop some out and smear it on the wall. If you are hiring a tile contractor to retile a shower and he hauls out a bucket of stuff to stick the tile on, and it’s all ready to use instantly, it’s mastic. What he should be using is real thinset cement, which is always a powder in a bag that he has to mix with water first before it’s usable.

Can a mastic shower be saved if tile are coming off the wall? It depends. If you have more of the original tile, we might be able to replace some of the broken or cracked ones, or maybe even scrape off the back and re-use some if that’s feasible. Tile repair is tricky and takes more skill than original installation, so we do charge extra. When we finish a repair, we almost always regrout the shower so the new grout on the repair won’t ‘stand out like a sore thumb.’ The repair part of the job might be under a hundred dollars if it’s a few tiles, or it can and has run over a thousand dollars for more extensive repairs. What a waste for the homeowner because the tile setter was too lazy to use the right thinset cement and used mastic instead!

We’ll do a post on why mastic is used and where it’s OK to use it, maybe later next week. Meantime, if you’re having tile installation or a tile shower built, just call the builder or tile guy and insist that he or she brings no mastic in your house. You’ll be better off and hopefully a mastic manufacturer will go out of business.

If you live in any of the towns listed below, and you suspect you’re a victim of mastic tile work, and you need either tile repair or regrouting, give us a call at 617-500-9271 or fill out this form below and we’ll get right back to you with an instant quote and any help we can offer. I should note that our repairs are done the way mechanics work: since most of the important issues are hidden, we work by the hour to fix them. Meaning we can’t always know the final bill before we start, but we can estimate it based on other similar repairs we’ve done.

Towns where Boston Grout does tile repair: 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.

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