Just had a new shower installed, tiles going down and overlapping the flange of an acrylic shower base. Contractor "sealed" the tile/base connection with grout, which soon cracked due to weight in shower and flexibility of base. I then used grouted caulk, which now has also cracked.
How can I seal this small gap in a way that will not crack? Or maybe I should not worry about it (concrete backboard behind tiles).
I'd get the contractor to fix it. I don't like the idea that the base flexes so much. I'm no expert but maybe there should have been a solid mud base under it. It can take many months for leaks to develop if the job was not done right in the first place.
Did contractor pour a bed of concrete or other material under the shower base to prevent flexing? If not, the flexing will continue. At this point, I would remove the grout and use a silicone tub and tile caulk that can flex a little.
Your "contractor" is lame! 1. Weight should not cause flex of the joint. 2. Use caulk for wall/floor joins. Call him back and tell him to do it right; follow up by putting the issues in a nice, business-like letter and send it certified mail. That's so when it cracks for the umpteenth time (pessimistically speaking), you have proof of the condition and when it occurred.
The popular opinion is that corners crack, if grouted, because of movement with expansion/contraction, so a flexible caulk is used.
Having cement board is not a reason to allow any moisture to seep behind the wall! Jeesh!
Properly applied it won't collect soap scum and moisture. Surface needs to be absolutely clean (wiped prior with full strength bleach) and dry. I get a tiny bit of mildew growing in the lower corners of our shower stall - I just use Scrubbing Bubbles once in a while, and brush down with bleach mebbe once a year. I leave the curtain open a bit on both sides so air can circulate, and we have a timer on the exhaust fan so it runs longer than we're in the room.
*That shower pan should not flex. There should have been a small pile of cement put down and then the pan pressed down onto it. The short term problem is what you are experiencing now. The long term problem is that the pan will eventually crack.
GE pure Silicon caulk is made for just that purpose. Get the gaps well cleaned and even rinse some denatured alcohol down thru them (with exhaust fans on FIRST), to caulk will adhere the best. Silicon caulk is a tad expensive, but never hardens, allows pieces to move around without losing the seal, and seems to last forever. I pull apart some pieces once that had
1/4" beads in it; it was still perfectly adhered, still very flexible, and was still doing its job; this was 18 years after I put it down, too. Make sure it's silicone; those with just a % of silicone still allow it to harder after a few years and don't do nearly as good a job. Any good hardware or home store seems to carry it. It stinks while it's curing, comes in clear or white and sometimes other colors. "Clear" isn't really clear; more like a faded window covereing. There's sometimes a temptation by some to use it as a glue; don't! Since it's so flexible, it'll still "run" over time and stretch thin between two movable or widely separated parts. I love the stuff. No monetary interest in it, but I do wish I'd bought some stock in it!
As for small/tiny leaks: They still should be fixed. They're a home for mold, just waiting for it to move in. You want to be careful of creating places mold can get into; it can be VERY expensive once it gets to the point of making people sick. Well IF it gets that far; it's not a given or anything but best not to take chances. Oh, and all shower/tub enclosures I've seen in the last few years say to use the Silicon caulk, too. To keep it from sticking to your fingers, dip them in cooking oil; works great! Don't get it on your clothing; it'll never come out.
Yeah, I'd agree with you but his descrip made it sound like a LOT of time has passed and he's also tried to make fixes of his own, which likely negated any warranty. He'd most likely have a losing battle on his hands there unless it was a really pro-attitude contractor. And you're right; there should never be any space under a shower pan, regardless of the circumstances. It can even crack the cement over time. I learned that the hard way on our last home.
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