Movement Joints: Where needed for stairs leading up to spillway spa?

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Michelle MG

Member
Aug 27, 2024
17
Livermore, CA
Hi there. I'm new to the site due to an issue coming up with our completed renovation that I can't figure out. Any help would be much appreciated!
  • Just a few weeks after tile and grout were put in we found some cracks in the two side stair areas of the spa wall.
  • This was after having realized that they did not have movement joints in the coping on the stairs (we noticed cracks in that mortar)- and we pointed it out and they cut the mortar out and installed mastic. The tile grout was installed the day after they cut those joints.
  • That was good, but soon after we got the grout cracks. The PB general guy told me maybe it was due to the heat during installation, but to me it seems then it would be everywhere- not in certain spots. And there was a big crack in some coping mortar leading to some of those cracks- so it looked like stress cracking to me.
  • The PB later had a mason come out to fix the cracking, and he brought only caulk with him. He said if they regrout with the same poly cement grout it will just crack again- so I guess he was agreeing it was stress of some sort. But is that normal?
  • I did not like the idea of using caulk all over the spa wall (and he had the wrong color)- so I did not let him do that work- but I let him use caulk in the one coping mortar crack above the sheer descent. I told him I need to think about this more and we'd need the correct color anyway for the tile area.
  • As I've done research I'm not clear on what to do and I also am wondering about the cause of this. Here are my questions:
QUESTIONS:
  • Please see my diagram of one side (other side is having the same issue)- to show where we have movement joints and where cracking is.
  • They only cut the mortar in the flagstone coping- the rest of the stairs below is still solidly connected to the concrete decking as far as I know. Should they have built the stairs in 2 chunks? What is normal best practice for this sort of structure?
  • If they should have made a movement joint through the entire stairs, is this something they could rectify now by cutting through?
  • If this is not advised or possible to cut them entirely, what would work for fixing the cracked grout?
  • Will acrylic siliconized caulk in place of a lot of the tile grout work well- or will it be too soft to keep tiles in place? And will it fail every few years?
  • Would replacing with epoxy grout instead be flexible enough to solve the problem- or will it crack also?
If this is just purely a cosmetic issue, then maybe we can live with it- but I don't want it to keep getting worse and everything fall apart very soon. I just don't know how much to push the PB and what to push for to be fair to us and them. Also- the surfacing has been finished now and water is in the pool. I'm not looking forward to another regrout job (they had to redo it all earlier due to installing the wrong color the first time).

Thank you so much in advance for any help!
 

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Please show us pictures of the actual problem areas.

Cracks are caused by movement. If the ground or structure is not stable then no amount of grout or caulk will fix the root cause of the problems.
 
ajw22 said:
Please show us pictures of the actual problem areas.

Cracks are caused by movement. If the ground or structure is not stable then no amount of grout or caulk will fix the root cause of the problems.
Click to expand...
I will get some pics loaded up here soon.. we have not had any earthquakes lately.. and I'm not seeing these cracks in other areas of the pool. The only thing I would think would have moved would be the clay soil under the concrete decking contracting due to these last months in summer heat. And I would have thought if those stairs were not a sort of solid bridge between the decking and the spa wall, that the spa wall would not be affected- but unfortunately currently it is all connected since there's no cut all the way through the stairs.
Anyway- I will get some pics later today. Thanks for the reply.
 
OK here are some pictures:
  • 2 pics of sample cracks. It is in many places in the side walls that have the stairs- so I can't show it all.
  • 1 pic that shows a crack in the coping mortar connecting to tile grout cracks: I did have the mason guy fix that brown mortar with caulk (after this picture was taken).. but didn't want him to do anything more than that until I figure out the best plan of action.
  • 1 diagram of where I know cracks are for sure within the tile area- although it may not be accounting for all of them- and does not show coping cracks.
  • 2 pics of the entire spa wall / stairs for overall reference.
Thanks again in advance for any ideas or thoughts of what causes this and what possible options we may have to make it better.
 

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Michelle MG said:
I will get some pics loaded up here soon.. we have not had any earthquakes lately.. and I'm not seeing these cracks in other areas of the pool. The only thing I would think would have moved would be the clay soil under the concrete decking contracting due to these last months in summer heat. And I would have thought if those stairs were not a sort of solid bridge between the decking and the spa wall, that the spa wall would not be affected- but unfortunately currently it is all connected since there's no cut all the way through the stairs.
Anyway- I will get some pics later today. Thanks for the reply.
Click to expand...
Hi ajw22, I had posted some pics that day- but realized now that I didn't put that as an answer to your response-(see below in main thread) so maybe it did not let you know. Any thoughts you may have further on this would be appreciated. Thanks!
 
Those all look like shrinkage cracks. Maybe also caused by some thermal expansion.

Mortar and grout lines need periodic maintenance. Remove any loose material and put a layer of grout on top to seal the cracks.
 
ajw22 said:
Those all look like shrinkage cracks. Maybe also caused by some thermal expansion.

Mortar and grout lines need periodic maintenance. Remove any loose material and put a layer of grout on top to seal the cracks.
Click to expand...
Thanks for looking.. so this is brand new grout- is this to be expected within a few weeks always of new grout? Then I'd have to do new grout many times per year to keep it nice? Or do you think one new layer at this point could keep it nice for a longer time?
 
Michelle MG said:
Thanks for looking.. so this is brand new grout- is this to be expected within a few weeks always of new grout?
Click to expand...

Have you spoken with your builder about it?

How hot was it when the grout was put on?

Michelle MG said:
Then I'd have to do new grout many times per year to keep it nice?
Click to expand...

You probably need to plan on touching up grout lines annually. You will probably see some cracks develop every year.

Michelle MG said:
Or do you think one new layer at this point could keep it nice for a longer time?
Click to expand...
Hard to say.

Michelle MG said:
Also- how can you tell visually the difference between shrinkage and movement cracks? TIA.
Click to expand...

Educated guess.

Movement cracks are usually larger. These look like spider cracks. Grout and mortar is hard and just a bit of shrinkage causes it to crack.
 
ajw22 said:
Have you spoken with your builder about it?

How hot was it when the grout was put on?



You probably need to plan on touching up grout lines annually. You will probably see some cracks develop every year.


Hard to say.



Educated guess.

Movement cracks are usually larger. These look like spider cracks. Grout and mortar is hard and just a bit of shrinkage causes it to crack.
Click to expand...
I did speak with the PB and they sent a mason out who wanted to caulk (siliconized acrylic caulk) to fix them all- but he had the wrong blue color and I wanted to do more research before letting him do that- so I only let him do it to the brown mortar above the sheer decent- not to any of the blue tile grout. Is caulk the right solution?

I also was thinking this may be a more structural problem- due to that the stairs are still connected below the coping to the concrete decking which has clay soil under it.. what do you think about that- were they supposed to cut all the way through the stairs instead of just the top coping being cut?
 

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Michelle MG said:
I did speak with the PB and they sent a mason out who wanted to caulk (siliconized acrylic caulk) to fix them all- but he had the wrong blue color and I wanted to do more research before letting him do that- so I only let him do it to the brown mortar above the sheer decent- not to any of the blue tile grout. Is caulk the right solution?
Click to expand...

I am not thrilled with using silicone caulk. I don't think it will last outdoors. And once you put silicone down you will never get grout to adhere on top of it. Silicone caulk is a quickie patch over doing new grout.

Michelle MG said:
I also was thinking this may be a more structural problem- due to that the stairs are still connected below the coping to the concrete decking which has clay soil under it.. what do you think about that- were they supposed to cut all the way through the stairs instead of just the top coping being cut?
Click to expand...

I don't think you posted any pictures of the steps problem. I need to see what you are describing.
 
Michelle MG said:
I did speak with the PB and they sent a mason out who wanted to caulk (siliconized acrylic caulk) to fix them all- but he had the wrong blue color and I wanted to do more research before letting him do that- so I only let him do it to the brown mortar above the sheer decent- not to any of the blue tile grout. Is caulk the right solution?

I also was thinking this may be a more structural problem- due to that the stairs are still connected below the coping to the concrete decking which has clay soil under it.. what do you think about that- were they supposed to cut all the way through the stairs instead of just the top coping being cut?
Click to expand...
ajw22 said:
I am not thrilled with using silicone caulk. I don't think it will last outdoors. And once you put silicone down you will never get grout to adhere on top of it. Silicone caulk is a quickie patch over doing new grout.



I don't think you posted any pictures of the steps problem. I need to see what you are describing.
Click to expand...
Yeah- I thought caulk was NOT a good solution... but the mason said if they redo grout it will just crack again- which makes me think they think it was NOT too hot a day when they installed it? (it was 90's- so it was hot- but if they think installing it now on a 70-80 day will crack again- then they must think it is some other reason)


If you scroll to the top you will see my diagram of the steps. They put mastic in the coping only- the stairs below that themselves were not cut through- they are solid.
Here I went back in my photos to find one to show how they built the stairs- they are solid and bridge from pool wall onto decking. If they should have been cut in two pieces then I need to know that so I can see if they can do that now. Otherwise my fear is not only grout will always crack- but all the thinset too? Won't things just fall apart over time more than usual if the structure is wrong?
 

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ajw22 said:
I am not thrilled with using silicone caulk. I don't think it will last outdoors. And once you put silicone down you will never get grout to adhere on top of it. Silicone caulk is a quickie patch over doing new grout.



I don't think you posted any pictures of the steps problem. I need to see what you are describing.
Click to expand...
(I think I just lost my latest reply- so my apologies if I did not and they both come thru)
I was thinking the same- that caulk is not a good solution- otherwise why not just always caulk instead of grout?
The temp was mid 90's when they installed.. but they tell me now that if they regrout - even on a cool day- it will just crack again- so I think they don't think it was the temperature..

If you scroll to the top of this thread you will see a diagram of the stairs. They ended up cutting the mortar on the coping on the stairs to separate for movement between pool shell area and decking- but the underneath of the stairs is still solid. Here is a pic of from when it was being built to show how it is underneath.

If I find out this was not structurally the way it should be- I would want to see if they can separate it now. Because leaving it connected if it should not be would make the whole spa wall start crumbling over time (sooner than normal wear)- wouldn't it?
 

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It looks like the stairs are poured as part of the pool structure during gunite/shotcrete.

You need to understand what things are the pool structure and what is the deck structure. The pool structure were created when the gunite/shotcrete were poured. Expansion joints should separate that structure from any deck that was subsequently put on the ground.
 
ajw22 said:
It looks like the stairs are poured as part of the pool structure during gunite/shotcrete.

You need to understand what things are the pool structure and what is the deck structure. The pool structure were created when the gunite/shotcrete were poured. Expansion joints should separate that structure from any deck that was subsequently put on the ground.
Click to expand...
This was just a remodel- so they had demo-d the stairs down to rubble and poured concrete over that rubble and actually lengthened the tread from 9" to 12". Here is a pic of after demo and before they added concrete- and to my eye it looks like concrete- not shotcrete- but can you please tell me what you think? Thanks- you are helping me weed this down! :)
 

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Concrete or shotcrete does not matter.

What matters is where the boundaries are of the pool shell? I cannot see what they put the steps on top of and if any of it was the pool shell.
 
ajw22 said:
Concrete or shotcrete does not matter.

What matters is where the boundaries are of the pool shell? I cannot see what they put the steps on top of and if any of it was the pool shell.
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Unfortunately we weren't here when original pool was put in.. and I can't find a better pic of the demo state.. but - that last pic I sent- if you look at the lower left side- it looks to me like just concrete under the rubble. And if you look at the right side it seems there's a cracked line all the way down the rubble stairs that pretty much lines up with the coping edge that goes all around the pool- so my gut tells me it's there that the shell ends.

Also- my general guy had warned me there would be a visual line on the stairs of mastic for this purpose. But then the mason forgot to do that- and I saw cracks in the coping mortar there soon after- and when I showed them they then pulled the mortar out of those joints and put mastic- but that's all they did- they did not cut through the entire stair structure. So if this was a cake- they only unjoined the frosting layer- not the rest of the cake.

Would it make sense to make a movement joint of mastic only on the coping and not further down?
 
Michelle MG said:
Would it make sense to make a movement joint of mastic only on the coping and not further down?
Click to expand...

No.

But I am not sure I would worry about it with a small width deck and stairs. You do not have enough deck surface area to put a lot of force on the pool structure.

The problem an expansion joint deals with is when you have a deck sandwiched between a house and a pool. Then you have three large solid objects putting pressure on each other and something has to give, which is often the pool bond beam cracking.

You don't have that with dirt then a 3 foot concrete stains and then the pool.

If you are going to have an expansion joint then the two structures need to be totally decoupled, not just the frosting. Either do it right or don;t bother doing it at all.
 
ajw22 said:
No.

But I am not sure I would worry about it with a small width deck and stairs. You do not have enough deck surface area to put a lot of force on the pool structure.

The problem an expansion joint deals with is when you have a deck sandwiched between a house and a pool. Then you have three large solid objects putting pressure on each other and something has to give, which is often the pool bond beam cracking.

You don't have that with dirt then a 3 foot concrete stains and then the pool.

If you are going to have an expansion joint then the two structures need to be totally decoupled, not just the frosting. Either do it right or don;t bother doing it at all.
Click to expand...
OK. The stairs on one side of the spa are about 6.5 feet and almost 8 feet on the other side- so a bit more surface then three feet. But I get what you are saying. And we do have very clay soil which definitely expands/contracts a lot with the seasons.

For this situation, though, I'm not only concerned about the pool bond beam (good to know you think that is okay given the situation)--- but I'm concerned it is going to continue to create cracking on the spa wall over and over- even if we try to regrout every time- and maybe make tiles fall off way faster than if it was properly decoupled--since we immediately got cracking all in the area of the stairs after install.

And why would the PB admit to needing to cut the coping mortar but did not cut all the way through? Do you think it would be too hard to cut all the way through at this point?
 
Yes, it will be hard to cut concrete that deep to create an expansion joint.

There are concrete saws but you can only cut as deep as the depth of the saw blade.

All of this should have been figured out before construction began. I assume you had no construction plans showing what they were going to do.

Pre-Cast_Coping.png
 

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