Gunite pool no expansion joint?

[AndieR]

Hi!

We gave a 1960s gunite pool that we just had replastered. We also replaced the coping and tile. Its looking great.

This said I read that pools are supposed to have an expansion joint between the coping and the deck and ours only has grout. It never had the joint, not before the remodel and not now.

Long story theres been a vertical crack that keeps coming back for decades. It’s been fixed several times to include staples. The crack always starts at the deck slab and then the tile and downward. This time around we decided to dig the soil at that spot and check for roots and in doing so we found that the deck slab has a huge 1” crack really. So it looks like the weak point is there.

Could the reason for the pool crack be the lack of expansion gap? We didnt know that was necessary and have never been told.

How do we ho about creating the joint? We just remove the grout?

Thanks,
Andie

 

[ajw22]

Welcome to TFP.

The placement of the expansion joint depends on the type of deck you have. Read Expansion Joints and Coping - Further Reading

Post pics of your pool, the coping, deck, and where the cracks are.

 

[AndieR]

Thank you! Here are some, I’ll post better ones when I’m back home.

But you can see what it looked like without the old coping, and then with the new coping and also a close up of the crack in the deck slab where the pool usually cracks. We think it may be the deck moving that leads to that crack.

We opened it up to repair it and realized past the surface it was much wider and deeper than we expected. Right now there is no crack visible in the pool plaster since we remodeled recently but again it has cracked multiple times in the past.

Hopefully you can see how the coping grout touches the deck. No joint there.

Thank you,
Andie

 

[AndieR]

See photos above.

 

[ajw22]

Lack of an expansion joint is not causing that vertical crack.

The crack keeps on opening because the area has not been properly strengthened with concrete staples. It looks like the crack was just filled with epoxy.

Torque Lock

Concrete Crack Repair Staples for Swimming Pools and Pool Decks | AquaStitch

Torque Lock Structural Staples - Misleading Information About Repairing Your Pool Crack

Are you tired of misleading information about repairing a pool crack? It's time to call and ask about Torque Lock Structural Staples.

torque-lock.com

 

[AndieR]

Got it, thank you for the links! Weird question I know, but does it make a difference if we add the staples to the outside of the pool shell vs the inside? Or is it safe to say that regardless they will help stabilize the crack?

Also, what’s your opinion about adding an expansion joint to the pool? Is it necessary?

Thank you,
Andie

 

[ajw22]

Got it, thank you for the links! Weird question I know, but does it make a difference if we add the staples to the outside of the pool shell vs the inside? Or is it safe to say that regardless they will help stabilize the crack?

The staples should be on the inside of the pool so that the pieces are tightly held together.

Adding the staples to the outside of the pool can let the crack open inside the pool like a V.

Also, what’s your opinion about adding an expansion joint to the pool? Is it necessary?

I need to see pictures of the buildup of your coping and deck.

From the picture you posted it looks like your coping is maybe 2 feet wide and then you have a gravel border and then grass. That is hardly a deck.

 

[AndieR]

Not sure what you mean by gravel, that’s the top texture of the slab, rainbow pebble. It’s a common style for 1960s pools here.

The coping is 12” wide and the slab around is poured cement about 2’ wide and 4 inches thick. There is no joint between the coping and the cement slab.

 

[ajw22]

Not sure what you mean by gravel, that’s the top texture of the slab, rainbow pebble. It’s a common style for 1960s pools here.

The coping is 12” wide and the slab around is poured cement about 2’ wide and 4 inches thick. There is no joint between the coping and the cement slab.

I see it now. The joint with the red line should have been an expansion joint.



Your problem is that the pebble slab looks like it is coupled to the bond beam. There is not a gap between the slab and the bond beam to create the expansion joint.

Have you had problems of horizontal cracks in the bond beam and tiles cracking and popping off?

Your pebble slab is not very wide and may not be able to put a lot of pressure on the bond beam to need an expansion joint.

 

[AndieR]

No horizontal cracks, just that vertical crack that starts very wide at the slab — over 1” wide and 4” deep. Basically the slab is fully cracked at that spot. We dug under the slab and we can see that the crack runs through the bond beam and then tappers off at the shell level and becomes hairline.

This is a pic of what it looks like under the slab where we can see the crack into the bond beam?

 

[ajw22]

I need to see a wider picture for context on that crack.

@AQUA~HOLICS should have a look at this.

 

[AndieR]

See a few from today, again consider that before the remodel this crack would go through the old coping and then down the tile and down the top foot or so of the shell inside the pool. It always looked like the rest of the vertical crack was mostly just hairline plaster crack. But at the very top the tile always ended up popping off and you could see a thin crack like maybe 1/8 of an inch.

So the crack in the pool was super thin compared to what we’re now finding under the deck slab

There were also some roots in there that we cleared but not sure if the roots just grew that direction because of the leak.

I should add that a couple big pieces of the slab just fell off the grass side edge when we started digging. You can see that on the pics too. So even though we did widen the surface crack to repair it we weren’t expecting it to go all the way through and be that wide/crumbly.

 

[ajw22]

Lack of an expansion joint did not cause that crack.

Next time it cracks, in a few years, let's talk about concrete staples for the crack.

 

[AndieR]

Thank you, do you think filling the existing crack you see under the slab with hydraulic cement would be the right thing to do? Should I just use that to fill the slab crack as well or make that into some form of expansion joint? Sorry about all the questions!

 

[ajw22]

You need to support the slab and give it a solid base. I would pack gravel under the slab.

Gravel Around Pools - Further Reading

www.troublefreepool.com

The crack in the slab I would fill with mortar, not hydraulic cement.

Hydraulic cement expands and you don't want the patch creating pressure on the slab that is already crumbling in places.

I think you will be replacing the slab deck in a few years.

 

[AndieR]

Ok thank you that helps! Yes, we want to replace it even now but the pool company is slammed so we’d like to see if we can get through the summer without this crack reappearing in the pool. They tried their best I think but we just want to also repair the deck to give it an extra chance.

Thank you again!

 

[AQUA~HOLICS]

Sorry for the late response, taking everything into consideration, movement is occurring in that area of the pool and the weaker concrete’s are having larger issues than the pool shell that is the strongest of all the surrounding materials.
The top priority is the vertical crack in the pool shell and finding the cause for it continuing to reappear.
In the second picture provided it appears that the area past the crack (deck) is open area without concrete work.
This makes it difficult to follow the movement and determine its severity.
What is different is that the pool shell crack is pulling apart and the deck is heaving.
Hard to say exactly what’s causing this issue without more detailed pictures.

 

[wireform]

I wouldn't do a new deck till the vertical crack is addressed with staples as mentioned above.