How concerned should I be about these cracks??

JK in PHX AZ

Active member
Jul 19, 2019
28
Phoenix, AZ
Hi all,
I have a gunite pool, 2.5 years old, that is showing evidence of stress cracks in the bond beam/waterline tile, and extending down into the pebbletec and gunite below. Currently two cracks, the newer one being larger and more concerning. First two pix are the smaller original crack, coming off of a pier at the back wall of the pool. That crack extends down into the pebbletec about 3 feet or so, but is a hairline crack from the waterline down. The pebbletec is very slightly discolored down the length of the crack. The other pix are the larger crack at the front coping, which is pretty large (1/8" wide) at the top, and gets narrower as you go down into the pebbletec. The pebbletec here is cracked 18" down, turns a radiused corner, and goes another 18" on the floor of the pool itself before it disappears.
My questions are: how much of a problem is this, aside from the cosmetic issue?
Aside from repairing the grout at the joints of the waterline tile and the coping, how are cracks in pebbletec repaired; is pebbletec repairable while immersed in water, or does the pool level need to be lowered to repair/fill the cracks?
The pool rebar was done correctly, at 6" on center for the full floor and walls. But we have extremely expansive soil in this part of Phoenix, so although the rebar was done with belt and suspenders, there was always a chance this type of ground movement could cause a crack. Now I just need to get smart on how to address the repair of these cracks.
Water loss is being measured, I'm in day two of a bucket test, and so far things are not encouraging. First 24 hours: bucket down 5/16", pool down 11/16", so 3/8" more than the bucket. Second 24 hours: bucket down 5/8", pool down 1 7/16", so about 3/4" more than the bucket.
Is it really possible that these cracks are causing me to lose over 160 gallons per day? I guess you don't need to be Einstein to conclude that the answer is "yes". But if anyone could confirm that cracks of this size could really leak that much water, I'd appreciate the insight.
Thanks,
Jim KIMG_5118.jpgIMG_5119.jpgIMG_5120.jpgIMG_5121.jpgIMG_5123.jpgIMG_5127.jpg
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
12,670
Houston, Texas
I would do a dye test on the cracks under the waterline. Turn the pump off and let the pool sit undisturbed for a few minutes, and then squeeze some food coloring near the cracks. If you see the food coloring getting pulled into the crack then that is a leak. If the food coloring just dissipates then the crack is cosmetic and not leaking.

Have you talked to the builder about your concerns? The pool should be under warranty if it is only a couple of years old.

@JamesW , @jimmythegreek , what do y'all think?
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,167
Central California
Shoot. No expert here, and I hope I'm not alarming you over nothing. More like preparing you. If the crack is in just one material, like just the pebble, or just the grout, then that could be a defect in just that material or its installation. But if the crack spans more than one material, and if I'm seeing the pic's correctly, it looks to be three or four (the pebble, the tile grout and the coping grout, and maybe another), then that is indicative of a failure in the material behind all of those (the shell). Let's hope not.

Do all those cracks align? All in one area of the pool?
Fingers crossed while we wait to hear from our builder experts...

Sorry, I was commenting on the pics, not the text, which I just re-read. It would seem your shell is in trouble. And it may be that fixing any cosmetics would just be postponing the inevitable. I have seen shell cracks repaired. @ajw22 might remember the thread in which he showed us how that's done.

A faucet dripping at 1-second intervals is 5 gallons a day. Based on your description of the cracks, I'd say 160 gallons a day would be entirely possible.
 
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JK in PHX AZ

Active member
Jul 19, 2019
28
Phoenix, AZ
Thanks zea3, I'll give that dye test a try...
Pool is 6 months out of warranty, and I went the owner/builder route, but the sub responsible for pool coping is coming by to take a look in a few days.
 

JK in PHX AZ

Active member
Jul 19, 2019
28
Phoenix, AZ
Hi Dirk, the cracks are at two opposite sides of the pool. Our pool is shaped like a rounded baseball diamond, and the older crack is back at the "center/left field" wall. The newer one is at halfway down the "first base line". We have horrible expansive soil in our neighborhood (expands when wet, contracts when dry), and it hasn't rained basically since February. There was always a risk of stress cracking due to this, but the rebar and gunite was engineered/spec'd to theoretically withstand this. Theoretically. I would wager that the cracks go well into the gunite.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,167
Central California
I would think so, too. Here's a thread to ponder (check out the video):

 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
20,352
Northern NJ
Post pics of your pool and deck especially around the cracked areas. Often cracks are caused by the deck not having a proper expansion joint and putting pressure on the bond beam. Before you deal with the cracks you need to get to the root cause of it. We need to understand what type of interface your pool and deck has.

 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
2,931
Morris Cnty NJ
Those cracks are definitely causing your leak. The larger one is likely thru the shell at this point. Do you have any details on the engineering design of the shell. You mentioned piers, that's why I ask
 

JK in PHX AZ

Active member
Jul 19, 2019
28
Phoenix, AZ
Those cracks are definitely causing your leak. The larger one is likely thru the shell at this point. Do you have any details on the engineering design of the shell. You mentioned piers, that's why I ask
Hi Jimmythegreek, attached is a pdf of the engineering specs. If you can't read something specific, lemme know, and I can zoom in on that area. Rebar is 6" on center, all walls and floors.
 

Attachments

JK in PHX AZ

Active member
Jul 19, 2019
28
Phoenix, AZ
Is anyone aware of any underwater-use epoxy or anything that I can throw in that larger crack temporarily, my PB is away for two weeks and I am bleeding 160 Gals per day. I am on trucked-in water, at 5 cents/gallon, and the water loss alone is gonna get expensive, not to mention the subterranean damage it might be causing. Any suggestions? I have a 3M epoxy gun and mixing tubes; would any clear epoxy apply and cure underwater? The sharp tip of the mixing tube could be held right at the crack.....?
 

rphpool

Well-known member
Mar 4, 2015
691
Sugar Land , TX
Check this out:
 

Rich D

Bronze Supporter
Aug 3, 2018
959
MA
I think I would try Dirk's suggestion first with the tape. I would try to keep the temporary repair as superficial as possible. I would hate to see you get epoxy too far down in there and hinder the permanent fix such as an epoxy injection.
 
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