Quick Question: Water Leak Test After Shower Mortar Bed Created?

[JasonCA]

Usually, a water leak test is done after a PVC linear or similar type of protection is finished being installed (this I've done). However, in my case with a PVC linear and after the mortar bed has been created and dried, is it safe to do another water leak test?

It seems once the mortar bed is created on top of the PVC linear and has dried (easily over a few weeks in my case), it is thereafter tiled over. However, is there any negative effect to performing a water leak test or simply running water over the mortar bed prior to tiling?

In looking around on the internet, I only ever see a water leak test done prior to the mortar bed being laid. Yet, what about after the mortar bed?

I would think it would have no effect on the mortar once it has cured and dried, but just asking to see if someone says otherwise?

[A. Spruce]

There is no need and no point to water test the mortar, it is not water resistant and has nothing to do with keeping the water contained within the pan or shower, it's only purpose is to support the tile.

[JasonCA]

Thanks for the response!

After laying the mortar and now that it has dried for a few weeks, before laying TILE, I wanted to fill the shower pan with water (flood it) and see where the water collects. Is there any harm to doing this? Its simply a way to check that the mortar is sloping correctly. For example, when the water lowers, if it pools in the corner, I will know I have a problem.

I can get the mortar wet? Or, I must first TILE before I can wet the shower pan again?

Thoughts on this?

[DanM]

If the shower pan is done correctly (sloped) you don't need to test it after the mortar bed is done on top of the liner. You can get the mortar wet before you tile. This style of shower pan is called water in, water out. Water is constantly going to be going into the mortar bed before it goes out the drain.

I have a quick question though, did you do a pre-slope? This is an important step. The pre-slope is a mortar bed you do on the sub-floor before you install the liner. Some crappy youtube tile guys don't do this but it's a huge no-no (any pro tiler that does top quality work will agree). The point of the pre-slope is so that water that makes its way to the liner will run toward the drain. Like the name suggests, this first mortar bed should slope towards the drain (1/4" per foot). After you install the liner you do a second mortar bed, this should also be sloped towards the drain (1/4" per foot).

[JasonCA]

Very helpful DanM!

Yes, I agree. The type of mortar sits on top of the PVC liner and so water will constantly hit it once the tile is put on it.

I am just not sure if I can hit it with water before tiling? Once everyone else does the morter bed, they seem to jump to the tile (which is OK if they are confident the bed is OK). It seems that it wouldn't hurt anything to flood the mortar bed a second time, but I just want to ask to be sure?

Yes, yes I did do a pre-slope at 1/4" per foot as required. However, the desire to flood it with water is just to sort of see where the water pools/puddles? I would expect it to puddle towards the drain, and not puddle around the edges of the shower. By filling it with water (a second time), I could just double check things.

The idea is that I'd like to flood it with water BEFORE doing the extra step of tiling. There's a lot of weight put on when the MUD is put in. I just want to make sure the pre-slope has NOT changed and is still doing what it should.

Then, with that confidence, let it dry after flooding it and then can go ahead and tile maybe a week later. It would be disappointing if after tiling, I find out the slope was messed up somehow (although I don't expect this). Then, I would have to rip everything apart including tile. I'm sort of wanting to go through that extra double step to double flood check before moving forward on the tile.

From what you are saying it sounds like it won't hurt anything to hit the mortar bed with water just enough to see where the water goes. The mortar bed was put in a few weeks ago so it's pretty dry by now. So far I have never hit it with water.

[DanM]

If you already tested the liner and made sure it's not leaking you're good to go. The mortar bed under the liner isn't going to shift at all once it's set, it's going to be rock hard. Cement based products are extremely strong against compression, and the added weight of the upper mortar bed isn't going to come anywhere near the maximum amount of weight the lower mortar bed can support.

There's no point in doing a flood test on the upper mortar bed either. The liner has already passed its test, and there's no need to test the mortar itself. It doesn't matter if any tiny spots of water pool on the surface of the mortar it's only temporary. Any water which doesn't directly flow into the drain will slowly go through the mortar until it hits the liner and then make its way to the drain.