Crack along sides of pool

[mike4088]

Hello, any idea why this pool has cracked? The crack runs along both sides, im guessing the pool cover rails and skimmer boxes are the reason but would like to repair thjs if possible and prevent the problem from coming back
. Pool is 20k inground not salt. Thank you.

 

[Bperry]

Hello, any idea why this pool has cracked? The crack runs along both sides, im guessing the pool cover rails and skimmer boxes are the reason but would like to repair thjs if possible and prevent the problem from coming back
. Pool is 20k inground not salt. Thank you.
View attachment 521044
View attachment 521045

What’s the condition of the expansion joint between the coping and the pool deck?

 

[mike4088]

What’s the condition of the expansion joint between the coping and the pool deck?

I just did the mastic myself actually. It was in bad shape on one side, dried out and not sealing out water whatsoever. On the other side of the pool the mastic is still sealing out water but it's a bit dry and not flexible in some places. No obvious cracking of coping stones or anything from above. Here's a better picture of the joint and crack. It's hard to tell in the 2nd pic but that crack goes the whole length of pool all the way to skimmer box. The crack is present on the opposite side of the pool but its not nearly as bad.

 

[wireform]

Seemingly a defect in the bond beam.

 

[mike4088]

Seemingly a defect in the bond beam.

So, to repair this I would detach the rail for the pool cover, break out the coping stones and then...remove the mortar they are sitting in and re apply mortar?

What is a bond beam exactly?

 

[Bperry]

I just did the mastic myself actually. It was in bad shape on one side, dried out and not sealing out water whatsoever. On the other side of the pool the mastic is still sealing out water but it's a bit dry and not flexible in some places. No obvious cracking of coping stones or anything from above. Here's a better picture of the joint and crack. It's hard to tell in the 2nd pic but that crack goes the whole length of pool all the way to skimmer box. The crack is present on the opposite side of the pool but its not nearly as bad.

That kind of crack can point to a lack of expansion joint. Before you replaced the mastic, was there an actual gap between the paver base and the pool wall (bond beam)? Sometimes a concrete paver base is poured right up against the pool wall without leaving an expansion gap there. Then when that giant slab expands and presses on the pool wall, something has to “give” and causes a crack like you see. I’d definately check what’s under the pavers and see.

 

[mike4088]

When I removed the old mastic I saw some leveling sand and I left it be. The expansion joint is not remotely symmetrical in some places the patio is lifted and in a couple the expansion joint gap is very narrow, 1/8th in maybe. Here are two pictures with old mastic removed maybe they'll help.

 

[ajw22]

The bond beam is the top of the gunite pool shell. Yours is probably cracked.

You should have a 1/2” gap between the deck and the pool structure. Putting mastic in a compromised expansion joint accomplishes nothing. The joint should have been cleaned out and opened before the mastic was put in.

See Pool Engineering Inc. - Minimizing Swimming Pool Structural Problems Due to Concrete Deck Construction

At this point the coping needs to be removed and the plaster along the crack stripped to examine the bond beam. If it is cracked it needs to be rebuilt with rebar and hydraulic cement, then coping put on, the expansion joint created, and the pool replastered.

Expansion Joints and Coping - Further Reading

www.troublefreepool.com

 

[ajw22]

See the pics of a cracked bond beam and repair in this thread…

Bond beam repair

You can mix it by parts easily. For 5 10' sections i would personally form it if I was making the repair. Super easy and fast and I can leave the site with no worries or babysitting. Nothing fancy some thin plywood or whatever is laying around my yard this isn't pretty formwork. Was...

www.troublefreepool.com