Linear drain - weep holes

[ndjur]

I'm redoing my bathroom and trying to decide which linear drain to go with for the shower stall. At the moment I narrowed down my choice to either 24" Kerdi Line or the new 24" ShowerPerfect by Mapei (actually - ShowerLine by QuickDrain). This may easily change depending on some answers I get here.
Not knowing anything about any type of drains, I think I read the whole internet from A to Z trying to understand how this whole waterproofing and draining thing works. Due to the lack of room under the floor, I decided to stay away from linear drains which are "secondary drains" that connect into the traditional drains.
I'm still puzzled by one important issue regarding the 'primary' linear drain and I'm asking you for some help here. My understanding is that the reason for shower waterproofing is that some water will always find its way to the other side of tiles and that we want to route that water somehow into the drain. That's why there is a slope with liquid or fabric membrane and weep holes in classical drains surrounded by gravel so they always work.
However, this doesn't seem to be the case with linear drains and I'm really confused about it. Kerdi Line installation video uploaded by Schluter

at 17:36 - 18:00 clearly shows application of thinset that will not allow any water under the tiles to go into the drain. What am I missing here?
Another drain that I like due to its apparent ease of installation is ShowerPerfect which does have very, very small weep holes that will probably clog up after just a few months of regular shower use.
Would you please help me understand this issue, and also let me know if you have any experience - positive or negative using the new ShowerPerfect drain.
Thanks a lot,
Nick

 

[ndjur]

Don't shoot the messenger.

You stated that you have no experience with any drain. If this is your first attempt at shower building and linear shower drains I would suggest sourcing A Professional in your area well versed in the system you choose.

Huge room for error and your talking about thousands of dollars in materials alone...The industry and people that dont build showers are being misinformed about EASE of these installations yet many tile pros who build showers and are attempting there first install butcher it as shown on the myriad of threads around the internet.

I don't know of your skillset so don't be slighted...out of the 2 sytstem''s you mentioned above the video shown is going to be the easier of the 2 choices. You may also look closer at Quick Drain USA and Noble thinbed as A solid THINBED linear set up. That is my preferred method for your concerns of Not using a clamping/primary drain.

Our resident Linear Expert JW has left the building......

Thank you very much for your response.
I do understand that there are many tricky issues regarding the installation of a linear drains, so I was not going to do the job myself. However, I did want to understand as much as possible, so I can at least identify a product that looks the most logical to me. Based on the decision, I would look for a pro familiar with the chosen drain.
At the moment, the weep hole issue is the main one I'm trying to get better idea about.
Thanks again.

 

[Sponsor]

 

[Jadnashua]

Essentially all drains designed for use with a surface applied membrane do not have weep holes. This is because the primary waterproofing is immediately beneath the tile and continues into the edge of the drain. If they had weepholes, that would be a path for water to go under the membrane, which is way wrong! You never want moisture to get beneath your primary waterproofing layer!

When you use a system where the waterproofing is then covered with what may be an inch and probably more of porous deck mud (conventional liner with a clamping drain), that is when it is required to have weep holes to allow any moisture that gets beneath to escape. With a surface applied membrane to a drain designed for its use, there is very little mortar there (that's why the method is call 'THIN'set), and any moisture that may penetrate tends to just evaporate out the way it came since there's very little place else for it to go.

The critical thing in any of these is that the primary waterproofing layer MUST have a MINIMUM of 1/4"/foot slope, otherwise, you can get pooling of water underneath the tile, and it can take much longer for it to evaporate. The vast majority of water used in a shower just flows down the drain. Some will sit on the surface and a very small percentage will penetrate into the grout or deeper into the structure. Water tends to move where both gravity and capillary action take it (which is either down, or to the drier area). It won't go very far IF you have no gaps under your tile and you have proper slope with a surface applied membrane. And, when your surface applied membrane is installed properly, that's as far as it can get. You don't tend to get moisture buildup or water saturation underneath a properly applied membrane and thinset tile installation. This is not the case with a conventional mudbed...once it gets damp, it tends to stay that way, and any excess flows out the drain via the weepholes. It can take months to saturate a conventional mudbed. Compare dense thinset verses porous deck mud...the later can hold a lot of moisture, the thinset can't.

 

[ndjur]

Thanks a lot for your reply.
It looks like I was not very clear with my question.
I don't expect linear drains to have the same kind of weep holes clamping drains do. However, I would expect that some water that ends up underneath the tiles (still on top of the membrane) can find it's way into the drain (powered by gravity due to the pan slope). The picture of Kerdi Line drain that I attached clearly shows that this is not possible and that this water will stay between the membrane and the tiles until it evaporates.
This is something I've been confused about - why not providing some weep holes, or slightly different drain design that would provide a way for this trapped water to slowly find its way into the drain.
If I understand correctly, you are basically saying that there is no reason for concern as the amount of water underneath the tiles is negligible. If this is the case, when it comes to the weep holes, both drains I mentioned in my post are pretty much the same.

 

[Jadnashua]

When installed correctly, there is no lip between the flanges of the linear drain and the membrane that seals it to the rest of the shower pan. IOW, there's nothing to stop water from weeping into the drain underneath the tile, but in reality, when directly bonded to the membrane, there isn't any if done right. Yes, some moisture can get through the grout and start to migrate into the thinset depending on the use pattern, but most of the time, it only wets the grout. But, it doesn't get very far, and typically evaporates. In a conventional liner with a mudbed, some of that will continue down into the mudbed (nominally, at least 1" thick and porous like a sponge). That just doesn't happen underneath the surface membrane unless possibly the thing is in a commercial situation where it is used for hours all day. In a typical residential situation, it dries out the path it entered...there is no other way for it to go. Thinset and grout is much denser than deckmud, which when used with a conventional liner, does need weep holes on the clamping drain. Not a problem with a linear drain and surface applied membrane.

Some of the differences between the various linear drain manufacturers are: the type of material they use, whether it is polished (it's covered with a grate, but some like it polished), how the membrane is sealed to the drain (some, like the Kerdi drain have the membrane already attached, some require you to use a proprietary sealant, some require the use of their special primer first, some require a liquid waterproofing material). Various companies offer different grates, and many of them include tile-in grates which tend to be the least expensive version, unless you're using a radically expensive tile! Some offer more lengths, and outlet locations. If you have lots of body sprays and shower heads, some offer a 3" outlet. Some will also build one to your custom requirements in relatively short order. AT a class in Laticrete's facility, they mentioned a 14' custom one they made for a health club, and another that was gold plated for somewhere in the middle east. A typical linear drain can cost 3-6x more than a more conventional drain for the same membrane's use.

 

[ndjur]

When installed correctly, there is no lip between the flanges of the linear drain and the membrane that seals it to the rest of the shower pan. IOW, there's nothing to stop water from weeping into the drain underneath the tile, but in reality, when directly bonded to the membrane, there isn't any if done right. Yes, some moisture can get through the grout and start to migrate into the thinset depending on the use pattern, but most of the time, it only wets the grout. But, it doesn't get very far, and typically evaporates. In a conventional liner with a mudbed, some of that will continue down into the mudbed (nominally, at least 1" thick and porous like a sponge). That just doesn't happen underneath the surface membrane unless possibly the thing is in a commercial situation where it is used for hours all day. In a typical residential situation, it dries out the path it entered...there is no other way for it to go. Thinset and grout is much denser than deckmud, which when used with a conventional liner, does need weep holes on the clamping drain. Not a problem with a linear drain and surface applied membrane.

Some of the differences between the various linear drain manufacturers are: the type of material they use, whether it is polished (it's covered with a grate, but some like it polished), how the membrane is sealed to the drain (some, like the Kerdi drain have the membrane already attached, some require you to use a proprietary sealant, some require the use of their special primer first, some require a liquid waterproofing material). Various companies offer different grates, and many of them include tile-in grates which tend to be the least expensive version, unless you're using a radically expensive tile! Some offer more lengths, and outlet locations. If you have lots of body sprays and shower heads, some offer a 3" outlet. Some will also build one to your custom requirements in relatively short order. AT a class in Laticrete's facility, they mentioned a 14' custom one they made for a health club, and another that was gold plated for somewhere in the middle east. A typical linear drain can cost 3-6x more than a more conventional drain for the same membrane's use.

Thank you very much for your very clear and thorough explanation. Unfortunately, the gold plated one will not match my diamond covered faucets, so I think I'll go with a PVC Shower Line by QuickDrain for now. Next time - gold.
Thanks again, it was really helpfull.

 

[TipsMcStagger]

Thank you very much for your very clear and thorough explanation. Unfortunately, the gold plated one will not match my diamond covered faucets, so I think I'll go with a PVC Shower Line by QuickDrain for now. Next time - gold.
Thanks again, it was really helpfull.

Bumping this thread in hopes that maybe the OP is still subscribed and can comment on his experience with the Quikdrain;

My GC, plumber and tile setter are each telling me to talk to the other guy with regard to choosing a linear drain. The tile setter has installed several linear drains but he said he simply installs what he's been provided with by the plumber/home owner. The GC says he knows nothing about them because that's the domain of the plumbing sub. The plumber said to ask the tile setter. This has become a vicious circle and I'm left to do the research myself.

The house is on a slab and my GC is telling me they use the "double waterproofing" method to build the pan; an initial preslope mortar bed covered with a rubber/PVC membrane, followed by a final mortar bed slope which is then covered with a liquid membrane (they use Redgard).

I've been researching linear drains for a week and just now came across the Quickdrain Showerline PVC drains.

 

[Addo]

Tell me what you think about this linear drain installation video:

By the way, best prices I found so far for these kinds of drains are from a store in Barrie. They do installations and can answer all these kind of questions. If you are interested https://kolani.ca/
Any suggestions on best brands?

 

[Jadnashua]

WHen you have a conventional liner and then the setting bed, followed by another waterproofing layer, you have a chance of trapping moisture between the two layers. Pick a waterproofing method, install it properly, and trust it.

Personally, I wouldn't build a shower with a linear drain that used a conventional liner.

Check out www.johnbridge.com where they specialize on tiling things with a bunch of active pros contributing. Here, it's sort of pot luck.

Whichever waterproofing method you choose, require at least an overnight flood test...24-hours is better. Better to find any issues at that stage versus after all of the tile is installed.