Gunite retaining wall waterproofing

[spartanduner]

My wife and I just purchased a home with an IG gunite kidney shaped pool. The rear wall of the pool extends about 3.5' above the water level and serves as a retaining wall for the slope behind it. This wall has a flagstone veneer placed over it and I have noticed what looks like water seeping out some of the grout lines probably from irrigation of the slope above. I don't believe the rear of this wall was ever waterproofed and am wondering if this is a standard practice when a gunite retaining wall is built. My plan is to remove enough dirt behind the wall to install a french drain near the waterline if there is not already one there and then apply a waterproofing material to the rear of the wall before backfilling it. Does this sound like the correct method of repair for this issue? There is also a waterfall at the top of this wall that flows down over the flagstone and has eroded some of the grout joints. Is this something that can be prevented or will it be something that I need to regrout annually or as needed?

Thank You,

Derek

 

[frustratedpoolmom]

Welcome to TFP....

I don't mean to be rude but...


We love pics....

 

[spartanduner]

I knew that was coming!!! My first post was from work where I didn't have access to any photos. Here you go. I understand the efflorescence underneath the waterfall but am concerned about the leaching in a few other location which I have taken pictures of. I also included a photo of a crack below the coping at the skimmer that I need to repair. Any tips for that one?

 

[spartanduner]

more pics

 

[spartanduner]

One more

 

[frankthailand]

Hello Derek
That plan of attack sounds good, make sure you buy a good quality sealer, and give it a few coats. At least three.

With the grout just regrout it it should last a long time, also that might mean a poolwater balance problem. you can check your CSI on the pool calculator.
good luck
Happy swims
Frank

 

[frustratedpoolmom]

Despite the troubles, it's sweet!!!!

 

[spartanduner]

Despite the troubles, it's sweet!!!!

Thank You we are really enjoying it.

 

[spartanduner]

Hello Derek
That plan of attack sounds good, make sure you buy a good quality sealer, and give it a few coats. At least three.

With the grout just regrout it it should last a long time, also that might mean a poolwater balance problem. you can check your CSI on the pool calculator.
good luck
Happy swims
Frank

Sounds like I have a lot of digging in my future! I think the cracking around the coping is just from the initial settling of everything. I say this because in talking to the neighbors we have learned that the pool and patio are only about 2 years old.

 

[cobra46]

It is common practice to waterproof the back of retaining walls and install a french drain at the bottom. Normally the french drain needs to be sleeved to keep roots and soil out and also should be covered with a fair amount of gravel. Your raised bond beam does not have a bottom like a conventional retaining wall so I don't know how you deal with that. Maybe you can create a false bottom.

 

[spartanduner]

It is common practice to waterproof the back of retaining walls and install a french drain at the bottom. Normally the french drain needs to be sleeved to keep roots and soil out and also should be covered with a fair amount of gravel. Your raised bond beam does not have a bottom like a conventional retaining wall so I don't know how you deal with that. Maybe you can create a false bottom.

I am not too concerned about creating a false bottom as I am only concerned with water trapped behind the wall and above the water line. I plan on waterproofing the wall and then encasing a sleeved drain pipe with fall of about 1/4 per foot in about 1' of 3/4" gravel at the bottom before backfilling.

I am just surprised that this was not done when the pool was built in the first place.

 

[revstriker]

It is common practice to waterproof the back of retaining walls and install a french drain at the bottom. Normally the french drain needs to be sleeved to keep roots and soil out and also should be covered with a fair amount of gravel. Your raised bond beam does not have a bottom like a conventional retaining wall so I don't know how you deal with that. Maybe you can create a false bottom.

I am not too concerned about creating a false bottom as I am only concerned with water trapped behind the wall and above the water line. I plan on waterproofing the wall and then encasing a sleeved drain pipe with fall of about 1/4 per foot in about 1' of 3/4" gravel at the bottom before backfilling.

I am just surprised that this was not done when the pool was built in the first place.

Just a thought.... I know that some do this when adding a French drain around a house: If you add some heavy gauge plastic under the stone, and under the French drain, this will force more water into the drain and out from behind the retaining wall instead of letting water filter down which could create pressure on the pool wall. I've seen this done to prevent the water from draining down and pressing against a basement wall.

As I said, just a thought, but it probably wouldn't hurt, and woudn't cost a lot.

 

[crabboy]

I just did something similar when I found that water was leaking from the bottom of my slide and washing a bit of mud into the pool. I fixed the leak with the slide plumbing, but decided to go 100% and improve the drainage behind the wall and seal up the slide really well. I dug down to the water line, put down a drain pipe with landscape fabric underneath, ran rocks wall the up the wall and separated the rock from the backfill with the fabric. This way any water that washes down the top of the dirt will fall through the fabric and into the rocks where it will drain away.

I had to dig a bit extra to find the 4" drain for the decking and tie the new drain into that. Lucky I had pictures of when I put that pipe in so I knew where to find it. That was a royal pain in the #*@&$& as the pipe was about 4' straight down and I had to go in head first to connect it.

 

[stever]

I like using the MiraDri product. It's a self-adhering sheet membrane. Very sticky and very thick. It's like contact paper -- just clean off the wall, let dry and stick. It'll stick to the next sheet to create a joint so well you'll never get it off. One person can do the installation, but it's easier with two (once it touches something, it does not want to come off).

For my taller walls I also put a MiraDrain in that channels the water to the drain at the bottom. I don't think I'd do that again. I can't see it doing much more than the MiraDri itself and it adds $$.

http://www.carlisle-ccw.com/Doco/ccw-mi ... 60-861.pdf

The French drainis a must, but also put in surface drains to keep the water from having to go through the soil. Any water taken out of play before it hits the waterproofing is good. I never tie surface drains into a french drain system, as it channels the water down to the base of the wall into a pipe with holes (yes it can work in reverse also).

Steve