Fill Gap Under Front Edge of Shower Floor?

[Mattf83]

Hello,

I am an inexperienced homeowner remodeling my small bathroom on an extremely low budget.

The most recent part of the project I completed was replacing an old shower base with a new one. It's an acrylic/fiberglass one like this: https://www.homedepot.com/p/DreamLi...ERCH=REC-_-pipsem-_-204047577-_-206282990-_-N

Long story short, when setting the base into the bed of sand mix/topping (as it said to do in the instructions for the base), I had a heck of a time with it. I probably put too much sand mix down. By the time I got done leveling it out and making sure it felt solid, there was a slightly-more-than-1/4" gap between the entire front edge/lip of the shower base and the subfloor below it. The base felt quite solid (and still does), so I figured I could just fix this later after the sand mix had set.

Now, I'm wondering what the best way for me to "fix" this is? I want to tile soon, and the tile is obviously supposed to run right up to that gap.

My current thought is to cut a piece of 1/4" concrete board that's the length of the shower base, and maybe two-inches wide or so, put a little thinset on the bottom of it, and slide it into place under the shower base so it's basically flush with the front. This should both cover up the gap and provide a little support for that very front edge of the shower (there's a void there where the threshold is, so all you really need to support is the very front edge, I would think.)

Then I could run the tile right up almost to the shower, and caulk the space between the tile and the shower base? This should basically cover up any sight of the gap or the concrete board filling it.

Any reason this wouldn't work? Any better ideas? Thanks!

 

[WorthFlorida]

....My current thought is to cut a piece of 1/4" concrete board that's the length of the shower base, and maybe two-inches wide or so, put a little thinset on the bottom of it, and slide it into place under the shower base so it's basically flush with the front. This should both cover up the gap and provide a little support for that very front edge of the shower (there's a void there where the threshold is, so all you really need to support is the very front edge, I would think. Any reason this wouldn't work? Any better ideas? Thanks!

If the gap is thick enough for the cement board it is a good way to do it. Caulking in this very wet area will look like crap in a year and caulking is to seal a joint, not fill it in. If the tile can slid into this gap and under the pan with its needed thin set, it would be another way to go. If not, fill that entire gap with grout. Put in as much as you can so it can carry weight. Be sure to put a sharp vertical edge on it so the tile can fit up to it. You want about an 1/8" gap between the tile and shower pan. When you grout the tile seal this joint up with the grout. After a while if a hairline crack shows from the grout drying and from any floor movement, you can fill in the usually a hairline crack with caulking. If there is no color match "clear caulking" is now available. Place some caulking on a very wet finger and smear it into the crack to force the caulking into it, then wipe away the excess that sits on top of the grout.

 

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[Mattf83]

If the gap is thick enough for the cement board it is a good way to do it. Caulking in this very wet area will look like crap in a year and caulking is to seal a joint, not fill it in. If the tile can slid into this gap and under the pan with its needed thin set, it would be another way to go. If not, fill that entire gap with grout. Put in as much as you can so it can carry weight. Be sure to put a sharp vertical edge on it so the tile can fit up to it. You want about an 1/8" gap between the tile and shower pan. When you grout the tile seal this joint up with the grout. After a while if a hairline crack shows from the grout drying and from any floor movement, you can fill in the usually a hairline crack with caulking. If there is no color match "clear caulking" is now available. Place some caulking on a very wet finger and smear it into the crack to force the caulking into it, then wipe away the excess that sits on top of the grout.

Thanks!

Filling it up with grout seems like a really good option, I might go that route actually.

I had also thought about sliding the tile itself underneath like you said, but it just clears so I don't think it will fit with the needed thin-set (which means the cement board would also not be able to have much thinset under it...)

 

[WorthFlorida]

You really do not need thinset under the cement board. If the fit is nice and tight under the shower pan, just use some construction adhesive to tack it down.