Iridescent Particles in Ardex's 8+9 Waterproofing - A closer look

[jadnashua]

I installed a corner Better Bench in my mother's shower. They advocate either installing it on top of the tile, or to the wall, then tile around it. I opted to tile first, then install the bench since there would be lots fewer cuts. This means drilling holes through your tile and waterproofing the hole, which needs to be done with care. It's easier if you installed blocking first, since your holes will be smaller. It feels a little flimsy until you fill it up with deckmud. I found that you needed to be careful trying to get the corner bench to slope properly since it appeared to be essentially built without that slope (wouldn't be an issue on a bench along one side or the back wall and a side). I suppose you could slope it only against one wall, but I wanted it to slope from the corner. I didn't feel comfortable trying one that was entirely cantelevered which is why I chose a corner one (although I could have used a rectangular one). The corner one was enough space, and it didn't impact the size of the standing area as much. When thinsetting on the tile, the edges are a little tougher, since the thinset will only get a really good bond to the deckmud that is exposed by the holes in the metal seat...it will bond some to the metal, but most of the bond will be to the deckmud, so careful burning in of the thinset is critical. There's no problem with the top since it is all deckmud.

If you want to make a box, then you might consider KerdiBoard or WediBoard. That could be tied directly into the waterproofing of the shower more easily.

It's best to have a steeper slope when using river rock or pebbles on a shower floor verses tile. While some thinsets might be okay, most are not designed as an exposed, wear surface. They tend to be more porous, and would collect more crud. There are some grouts that you could use to set them, though that would avoid that problem.

[johnfrwhipple]

The thought of mounting the bench over the tile is a bad one. Regardless of who says it's aloud or O.K.

Work is work. It's hard. Trying to make a hard job easier will net you a weaker shower. You will be stressing the wall tile with the bench when you and your wife use it. I have seen many of these benches go in online and I would suggest that the bench go in now before waterproofing. I would then tile the bench first and bring your cuts to it.

I would leave 1/8" room for expansion and silicone this gap. This will be a tank. A little more work but a much better build.

If you decide to attach the bench to the finished wall tile I would pretreat the sides where they meet the tile. To pretreat the sides I would run a thin bead of silicone 1/16" so that the metal does not make direct contact with the wall tile. This will act as a compression gasket. Also with this approach you will need to ensure there is no voids behind the wall tile. It could crack.

Between you and me I would never go this route. Just because the manufactures says it's OK does not mean that it is O.K.

They say you can install Kerdi and tile right away as well. Anyone who has ever pulled a tile up while setting knows the suction and force needed to do so. Anyone tiling over fresh Kerdi can not check the coverage or risk pulling the Kerdi right off the floor and wall. Industry guidelines say to check coverage. It's a no brainer. So because Schluter says it's OK does not mean its right. Same principle here with the bench.

JW

[Daler]

The thought of mounting the bench over the tile is a bad one. Regardless of who says it's aloud or O.K.

Work is work. It's hard. Trying to make a hard job easier will net you a weaker shower. You will be stressing the wall tile with the bench when you and your wife use it. I have seen many of these benches go in online and I would suggest that the bench go in now before waterproofing. I would then tile the bench first and bring your cuts to it.

I would leave 1/8" room for expansion and silicone this gap. This will be a tank. A little more work but a much better build.

If you decide to attach the bench to the finished wall tile I would pretreat the sides where they meet the tile. To pretreat the sides I would run a thin bead of silicone 1/16" so that the metal does not make direct contact with the wall tile. This will act as a compression gasket. Also with this approach you will need to ensure there is no voids behind the wall tile. It could crack.

Between you and me I would never go this route. Just because the manufactures says it's OK does not mean that it is O.K.

They say you can install Kerdi and tile right away as well. Anyone who has ever pulled a tile up while setting knows the suction and force needed to do so. Anyone tiling over fresh Kerdi can not check the coverage or risk pulling the Kerdi right off the floor and wall. Industry guidelines say to check coverage. It's a no brainer. So because Schluter says it's OK does not mean its right. Same principle here with the bench.

JW

Ok, good point -- thanks

[Daler]

Daler use the proper mesh (SK Mesh) for the 8+9. A roll is under $20.00 I think.

If you need a part roll I can send it to you. Let me know how much you need. If it's a half roll I'll split the cost with you. I go through the stuff like Kleenex.

JW

A generous offer, John -- thanks. But if I can make do with similar is also fine with me, so..

I called the only supplier in town that carries most of the Ardex product line. They do not carry the SK tape as their trades don't use it much. As indicated, it would be special order in large quantity. He instead suggested the Mapei Reinforcing Fabric used for Aquadefense (which to me looks similar to that of large format drywall mesh tape) of which I already had purchased in small bulk :

http://www.lowes.com/pd_185276-1295-...7C1&facetInfo=

[Daler]

................

I installed a corner Better Bench in my mother's shower. They advocate either installing it on top of the tile, or to the wall, then tile around it. I opted to tile first, then install the bench since there would be lots fewer cuts. This means drilling holes through your tile and waterproofing the hole, which needs to be done with care. It's easier if you installed blocking first, since your holes will be smaller.

What size of shower and size of BB did you put in?
We're tending toward the large 30" size in our 3x5 shower.
I can definitely see your point of simplicity but I'm tending to go with John's idea of installing before the tile. I've also 2x10 blocked the heck out of the stud walls for the BB as well as for a grab bar. It will mean more cutting but I think with the proper tile and tools there should be little extra trouble ..meh, I'll just buy more tiles

It feels a little flimsy until you fill it up with deckmud. I found that you needed to be careful trying to get the corner bench to slope properly since it appeared to be essentially built without that slope (wouldn't be an issue on a bench along one side or the back wall and a side). I suppose you could slope it only against one wall, but I wanted it to slope from the corner. I didn't feel comfortable trying one that was entirely cantelevered which is why I chose a corner one (although I could have used a rectangular one). The corner one was enough space, and it didn't impact the size of the standing area as much. When thinsetting on the tile, the edges are a little tougher, since the thinset will only get a really good bond to the deckmud that is exposed by the holes in the metal seat...it will bond some to the metal, but most of the bond will be to the deckmud, so careful burning in of the thinset is critical. There's no problem with the top since it is all deckmud.


"Burning in of thinset" seems to be a common theme here. It's a process I'm not familiar with and will need to investigate some more
Because of the nice finished appearance we also plan to trim most of the exposed ledges (seat, niches, curb) with Schluter Rhondec. We had good success with it in our main bath surround wall ledges ..albeit it was a big learning curve for this layman -- it was a juggle to install.

If you want to make a box, then you might consider KerdiBoard or WediBoard. That could be tied directly into the waterproofing of the shower more easily.

It's best to have a steeper slope when using river rock or pebbles on a shower floor verses tile. While some thinsets might be okay, most are not designed as an exposed, wear surface. They tend to be more porous, and would collect more crud. There are some grouts that you could use to set them, though that would avoid that problem.

Yeah, I kinda figured that might end up being the case. Perhaps we could thinset the individual pebbles really well then quickly go over them with a damp sponge to recess the thinset, let dry, then shallow grout with the appropriate grout ..or maybe epoxy grout?

[jadnashua]

The shower was a tub replacement, 30x60. Some tile and surfaces are so smooth or dense that thinset may not stick easily...dense porcelain is an example. If the thinset is mixed well, you usually get a decent bond, but especially with a bigger tile where you can't exert as much force per sq in, it really makes a huge difference if you burn a coat on the back of the tile, and you will see a difference burning it in on the floor first before spreading and notching the thinset just prior to setting the tile. Essentially, you do this by using the flat side of the trowel at a shallow angle and literally pressing hard as you spread some thinset over the entire surface. Think of buttering bread. With a porcelain tile, you may notice that it sort of beads up on your first pass, but once you've burned it into the pores, the only way to get the back of the tile clean is to wash it off. Once you have a layer intimately coating the back, you use the same flat edge to scrape off any excess and give you an effectively flat back surface. Once you then set it into the thinset, since it already has a full coat, it sticks MUCH better and you're assured of 100% coverage, assuming you spread your thinset properly first. This procedure is recommended for any large format tile. Smaller ones typically can be pressed and seated well enough without it, but it still doesn't hurt (except in the time it takes).

[Daler]

The shower was a tub replacement, 30x60. Some tile and surfaces are so smooth or dense that thinset may not stick easily...dense porcelain is an example. If the thinset is mixed well, you usually get a decent bond, but especially with a bigger tile where you can't exert as much force per sq in, it really makes a huge difference if you burn a coat on the back of the tile, and you will see a difference burning it in on the floor first before spreading and notching the thinset just prior to setting the tile. Essentially, you do this by using the flat side of the trowel at a shallow angle and literally pressing hard as you spread some thinset over the entire surface. Think of buttering bread. With a porcelain tile, you may notice that it sort of beads up on your first pass, but once you've burned it into the pores, the only way to get the back of the tile clean is to wash it off. Once you have a layer intimately coating the back, you use the same flat edge to scrape off any excess and give you an effectively flat back surface. Once you then set it into the thinset, since it already has a full coat, it sticks MUCH better and you're assured of 100% coverage, assuming you spread your thinset properly first. This procedure is recommended for any large format tile. Smaller ones typically can be pressed and seated well enough without it, but it still doesn't hurt (except in the time it takes).

Ah yes ..a similar process I used for my 12x12 marble tiles on the last project, only I called it back-buttering. A test tile setting back then had me amend my method -- it did seem to stick much better. I've read where some folks will notch the thinset on the back of the tile instead then 'burn' in some thinset on the wall ..a reverse idea I guess.

[Daler]

So, moving on.. when applying large format tiles, I was thinking on using some sort of leveling devices like I've seen online. Looking back I wish this had been used in my bathtub surround walls because, as much as I tried, they are not on a 100% flat plane. I believe it's called, lippage.

The local HD has items call 'Lash' spacers and wedges. My concerns would be: will they work ok for an amateur -- will I need 4 hands to manipulate the tiles and those gizmos? Won't the spacer bottoms raise the tiles too much in the thinset? And will they provide a nice 1/16" grout line?

[jadnashua]

The QEP Lash clips do work. The TLS system also works. The tool for the TLS system and the clips make it a little more expensive plus, the prep for using the TLS straps must be soaked overnight, so you need to remember. In both systems, you can reuse parts (the wedges or the clips) a number of times, so may not need as many of them as the straps. This assumes you aren't going to do it all in one day - you only need enough for that, since you can remove them the next day and reuse. And no, you shouldn't need 4-hands to make it work. The straps are about that 1/16" (you'd have to double-check their specs), so yes, a thin grout line is quite possible.

[Daler]

The QEP Lash clips do work. The TLS system also works. The tool for the TLS system and the clips make it a little more expensive plus, the prep for using the TLS straps must be soaked overnight, so you need to remember. In both systems, you can reuse parts (the wedges or the clips) a number of times, so may not need as many of them as the straps. This assumes you aren't going to do it all in one day - you only need enough for that, since you can remove them the next day and reuse. And no, you shouldn't need 4-hands to make it work. The straps are about that 1/16" (you'd have to double-check their specs), so yes, a thin grout line is quite possible.

Thanks. From their directions it looks like the Lash clip bottoms remain in the substrate ..one has to separate them by knocking off the tops once the thinset has dried, is this not correct? If this is the case, how can the clips be reused?

[jadnashua]

Both TLS and QEP leave the bottom of the strap under the tile...you can reuse the wedge or clip (the clamp parts) again. With the QEP wedges, people have said it can get pretty rough on the fingers inserting the wedge (I've never used them, just hearsay), the clip from the TLS require a tool to tighten which may make consistency more reliable but at a cost. The manufacturers have videos on their website...might be worthwhile viewing, then decide. I'd probably try either one. If I was going to be doing this a lot, I'd consider the TLS system maybe more favorably since you could amortize the cost of the tool over a long time. Either will work if you follow the instructions and should give a better, quicker result than not using one.

[johnfrwhipple]

I've had the chance to bit the lashing systems head to head. In the end the winning system was the Raymondi lashing system.

After a few jobs we have found that the time saved setting tile is lost in grout prep. In your wet zone you need 95% coverage and full coverage in the corners. This is not easy with any of the lashing systems.


With many of the builds we do we are often :Tweaking: the tile install a hair. The lashing systems work properly only when the substrate is perfectly flat. They are a pain in the ass if you check mortar coverage - Like you should and like outlined in the TTMAC and TCNA Specification guidelines.

JW

The mesh tape you ordered is not the same kind. Night and day different products.

JW

[johnfrwhipple]

It's a miracle. My wife is actually letting me take her Kitchen Aid hand mixer to work today. With her blessing (under protest and the promise to return in as is condition). I bought a new patch of Ardex 8+9 and will do a few small batch mixes today.

I also took a medium sized mixing bowl since these hand mixers are designed to work with them. I think it will make a better mix than a squared edge bottom of a standard bucket.

I'll start a few test boxes today and record the process here.

JW

[johnfrwhipple]

So, moving on.. when applying large format tiles, I was thinking on using some sort of leveling devices like I've seen online. Looking back I wish this had been used in my bathtub surround walls because, as much as I tried, they are not on a 100% flat plane. I believe it's called, lippage.

The local HD has items call 'Lash' spacers and wedges. My concerns would be: will they work ok for an amateur -- will I need 4 hands to manipulate the tiles and those gizmos? Won't the spacer bottoms raise the tiles too much in the thinset? And will they provide a nice 1/16" grout line?

The Lash system does raise the install about 3/16" the Ramondi under an 1/8". 1/16" grout joints are very hard to achieve and two small for most large format tile.

What is the curvature of the tile you bought?

What is the size of tile?

What type of layout are you using? Stacked, Running Bond etc...

JW

[jadnashua]

When using large format tile, you generally want or need moderately deep layer of thinset...I don't think any of the straps would be that big of a deal. The only time you can use a very thin layer of thinset is with very flat tile on a very flat floor which rarely happens. The instructions I've seen have the straps maybe an inch or so from an edge, so clearing the thinset that might ooze up shouldn't be a huge deal.