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Tub shower tile and backer board problem

Tub shower tile and backer board problem

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Old 12-07-17, 08:43 AM
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Tub shower tile and backer board problem

Howdy, I need some advice on how to proceed with a tub shower tile job. I hired a "contractor" to help me with a bathroom remodel, he was supposed to install the tub shower backer board (Hardibacker) and install tile. He disappeared and I have to finish the job.
So, the Hardibacker has a gap around the tub that varies from 1/2 to 7/8". This seems excessive, is it? If so how would I handle filling this gap?
Also, he used paper tape and mud for the Hardibacker joints and screws, some of it is bubbled up and some of the screws are just proud of the board. Should I sand away all that and reapply with fibermesh tape per Hardibackers instructions? It seems like most of the screws are stripped so pulling them tighter probably isn't an option.
For addtl info: the tub is a standard 5' steel/iron tub and was the only original thing left in place for the remodel and is installed right up against the studs. I will be using a combination of 4 1/8" sq and 4 1/8 x 8 1/4" tiles and some glass mosaics as a band or inlay (not decided what the design will be but the tiles are on site already). I don't have mortar or grout yet so advise on those as well please.
Tjabk you for any help, Bill.
 
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Old 12-07-17, 10:11 AM
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the Hardibacker has a gap around the tub that varies from 1/2 to 7/8"
I think this needs a picture to understand what the gap is.

he used paper tape and mud for the Hardibacker
Cement board uses fiberglass tape and mortar
 
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Old 12-07-17, 11:10 AM
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Gap as in the hardibacker board was installed above the top edge of the tub crating a gap that varies in size 1/2-7/8", making me concerned that there won't be enough support behind the tile. 1/8-1/4" I could see being ok as that's not so much wider than tile spacing and the bead of silicone would do ok.
this steel/iron tub does not have an upward turned lip to mount it to the studs like some modern tubs I've seen, so there is nothing in this gap except the stud space.
Thanks for any help, Bill
 
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Old 12-07-17, 11:35 AM
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I have seen tubs without an upturned lip leak many times. Even if there is not a full blown leak it's easy for water to wick under caulk that has pulled. It's not the best to enclose for a shower. If you have a basement or crawl space below it's a good idea to go underneath once a year and inspect for water damage. Often it only manifests above when the tub starts to sink or the tile moves when pushed or pulls away from the tub.

The gap between your Hardie Backer and tub is a bit much but a lot depends on the tile you install. A large thick tile can better bridge the gap without support while there is no chance with a penny tile. Where some trouble will come is when you grout. With nothing backing up the joints in that area the grout will push through. The grout in that area may also crack and fall out if hit or treated roughly since it's only sticking to the sides of the tile and may not have great adhesion as most tiles are glazed on the sides.

Definitely get rid of all the paper tape and sheet rock mud. It us totally useless in a shower/wet application. In fact you can remove it with a wet sponge. Once you get back to bare, clean backer use fiberglass tape and thinset mortar.

Screw heads often don't countersink fully into Hardie Backer so that's not a major issue. It's annoying when you go to spread thinset to set tile but it's not the end of the world. If the screws are stripped then they aren't doing much to hold everything in place. Remove the stripped ones and install another screw an inch or two away and don't forget to fill the holes with thinset to seal them off.
 
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Old 12-07-17, 04:33 PM
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I'm using Daltile wall tile in the sizes mentioned earlier.
The TapCon hardibacker screws that are proud and stripped it is the square drive inset that is rounded out stripped, but they are just barely proud and would be within the mortar bed I think.

Should I just fill the gap with mortar I'll be using for the tile?

i will be buying my supplies from Lowes, they are asically the only game in town or within 45 miles. So, knowing their brands what should I be looking for?

Thanks, Bill
 
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Old 12-07-17, 04:44 PM
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You can bridge the gap at the tub lip with tile, but major concerns that there is no tile lip on the tub. This makes you rely on caulk as your last defense against water - caulk fails all the time and you have no back up safety net.

The bridge between hardie and drywall needs to be cleaned up if regular joint compound was used. I would then go back with a mesh tape designed for cement board and a setting type compound which is not subject to water erosion like regular joint compound.

Again, your backer can be saved, the issues I have is the non-tile ready tub. What thickness of hardie did he use. If 1/4" then just tear it out as it is not designed for walls.
 
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Old 12-07-17, 09:47 PM
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The tub has the slightest bit of a raised edge along its top, probably enough to keep moisture from going past but certainly not enough for my rowdy 6 year old monsoon baths lol.
I was thinking maybe get some SS finish nails and set them as anchors in the studs in the gap and then run SS wire between them to act as substrate for mortar to fill the gap. Only other idea I had was to take ~4" wide pieces of the Hardibacker and slide wedge them into each stud space of the gap with construction adhesive buttered on each end and inside back edge. Or am I over-thinking this too much?
The Hardiebacker is for walls, so 1/2".
Bill
 
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Old 12-08-17, 06:01 AM
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There is only so much you can do with that tub. It's OK for a tub but not good for a shower or containing heavy splashes. The best thing you can do is give the caulk joint between the tub and tile a thorough inspection once or twice a year. If you find any spots where it seems the caulk has come loose from the tile or tub... replace it with fresh caulk. As Czizzi mentioned the caulk is the main defense against water getting into the wall.
 
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Old 12-10-17, 07:01 PM
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These are the only pics I had of the gap, it is worse elsewhere. You can see the slight top edge lip of the tub.
 
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Old 12-11-17, 05:59 AM
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Has the wall/tub surround been painted? That will affect the adhesion of thinset. Puting tile over a painted wall may be OK for a kitchen back splash that will usually be dry and see no abuse a shower is a different story.
 
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Old 12-11-17, 04:28 PM
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Looks painted with HydroBan which is a waterproofing membrane similar to RedGard.

The gaps are normal and nothing to worry about. Just plan your tile layout so a vertical grout line falls well outside that area and the majority of the tile is adhered to the backer board. I see nothing wrong at this point. Enjoy your build.
 
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Old 12-14-17, 09:42 AM
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The contractor painted the bathroom while I was at work (I was supposed to paint) and he painted into where the tiles would be but most of the tun/shower area is still bare hardibacker and the mud over tape. I guess it's a good thing he didn't mud the screws.
Ill be removing the mud and tape and the paint if needed. Then using the fiberglass mesh tape with mortgage and mortaring that gap between the tub and hardibacker.
I am going to lowes this weekend to buy supplies. I think I already have some fiberglass tape.
So, "thinset" and "mortar" are basically interchangeable terms here, right?
My local Lowes carries Mapei brand tile products. I'm using Daltile 4" square and 4x8" rectangle tiles (arctic white mainly and dove gray accent) in the field and I'll be putting a glass tile mosaic in an inlay or a band (design not finalized yet). Suggestions please on tile gap spacing, sanded or unsanded grout, and does mortar color matter much?
Thanks again for all the help!
Bill
 
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Old 12-14-17, 05:13 PM
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Wall tile would be 1/8" spacing that would match your mosaic spacing. Unsanded on the walls for a spacing that small.

If some of the screws are proud of the hardie backer, then do this. Trowel on a v-notched trowel and then back butter and trowel each tile to give you a little more mortar thickness to bridge the screw heads. Start at row number two and nail a level ledger to the wall to work off of. Set the ledger just shy of a full tile and when the ledger is removed, custom cut each tile to fit tight to the tub with maybe a 1/16th of an inch gap that will be caulked in the end. Your gaps are normal, you can bridge them with your tile.

LFT mortar will give you a little more stick and less sag for setting wall tile. Other mortars will sag and droop on walls.
 
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Old 12-15-17, 05:41 AM
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LFT?
in my world that's Liver Function Tests lol.
My local Lowes carries Mapei products, probably a smaller selection than most, this is a small store out in the country.
Bill
 
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Old 12-15-17, 07:15 AM
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LFT-Large Format Tile

They also make a type called "UltraLite" but doubt that it would be carried in a box store. This is my go to for any wall tile install. Very sticky and great initial tack.
 
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Old 12-17-17, 02:24 PM
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Have you considered running 1/4 round pieces where the wall tile meets the tub? That was the solution I came to when sealing a fairly large gap after I had filled it with thin set. I used adehesive caulk to set the 1/4 round around the tub and then used the same to grout. Caulking the planes between the wall and 1/4 round and along the tub lip gives a pretty good watertight seal. The 1/4 round helps to shed the water into the tub instead of wicking back to the studs. Dal-Tile makes matching 1/4 round tile to the field tile so it becomes inconspicuous.
 
 

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