Best coping-to-concrete deck gap sealant

[pwa2003]

Our pool has been "Under Construction" since March 2022. One thing that was never done by the GC was applying sealant to the joint between the concrete deck & Travertine coping. It cause a lot of Travertine damage over winter 2022/2023. We're going to get it all buttoned by a remodeling contractor up before the next winter, but wanted to see in the community had any preferences on sealant....

One contractor recommends SikaFlex and the other recommends NexusPro.

Some advice by the experts on this website would be helpful. The "gap" is pretty narrow-- I'd guess about 3/16" - 1/4"... if that matters.

Thanks

** UPDATE** I added jpg photos. The GC never added sealant in the gap and over the winter, the gap filled with water, some got underneath, froze and cracked every corner and parts of the deck heaved next to the travertine coping tiles....and the concrete contractor never applied a defined barrier between the travertine & the concrete he poured. They cam back with a saw and opened the expansion gap, although NOT well enough to avoid the cracking

 

[Bperry]

Our pool has been "Under Construction" since March 2022. One thing that was never done by the GC was applying sealant to the joint between the concrete deck & Travertine coping. It cause a lot of Travertine damage over winter 2022/2023. We're going to get it all buttoned by a remodeling contractor up before the next winter, but wanted to see in the community had any preferences on sealant....

One contractor recommends SikaFlex and the other recommends NexusPro.

Some advice by the experts on this website would be helpful. The "gap" is pretty narrow-- I'd guess about 3/16" - 1/4"... if that matters.

Thanks

Got pictures? The sealant caused damage or something else?

 

[MAPR-Austin]

I can't find Data Sheets for NexusPro, but I assume it is a high grade silicone similar to Latasil. If so then both are suitable for immersion and it comes down to color/availability/installer preference.

I've used both and personally I feel like the silicone is a bit easier to work with and can give a great finish if done right. Just depends on what the plans call for.

The prep will be important, make sure the inside of the joint is extremely clean and dry, and that the installer uses a primer if required. Maybe have them make a sample for you to make sure it is going to look good.

 

[pwa2003]

Thanks. Neither contractor mentioned the Latasil. Yes, I, too found the Nexus Pro silicone hard to gather data on, and nobody will sell it to the public-- must be a contractor.. Latasil seems to be easy enough to find-- even on Amazon, and in plenty of colors. If I properly mask the adjacent surfaces, is this a possible DIY project for a guy with a caulking gun or two? Is the Latasil better than the Sikaflex? Is the Latasil and/or Sikaflex "self-leveling"?? I have about 130-ish LF of gap.... and if I can find the smallest possible foam backer rod, I might just try it.... unless the community advises against it.

 

[Dirk]

Following. I need to make this decision this fall, too. Deck-O-Seal is a product I'm considering. Others here have used it:

Replacing seal between coping and deck

I have seen this referred to as "replacing the mastic", but the seal between my coping and the deck on my pool has developed a sizable crack. I assume this means replacement. The last time I had this done it cost me over $500. It looks like it could be a DIY job, though. Are there any...

www.troublefreepool.com

 

[trivetman]

I am amateur hour but I know that ive been told to avoid silicone products at the pool for the reason that eventually they will fail and its a real problem to prep a surface which has seen silicone for reapplication of the fill. Polyurethane doesn’t cause this problem

 

[wireform]

As @Dirk said I only know of his product from a pool that was just renovated. I think your bigger issue is the gap you speak of is way too small to accomplish what your trying to achieve. If I remember from this recent renovation the deck and coping were done by a different contractor then the pool replaster and when the second contractor who did the replaster came to quote he had mentioned he won't work on the pool because the deck contractor didn't put a gap between the coping and the deck. The initial contractor then came back to cut the gap and it was at least 5/8" wide. So don't waste the product on the gap if the expansion joint isn't wide enough.

 

[SecoSteve]

Looks like that gap isn't big enough(especially at the corners) and maybe it wasn't the water that damaged the coping. I'd hate for you to apply sealant and the problem continues. I have not put any sealant between my coping and decking yet. I wanted to wait a couple years for settling. I still have foam in between and I don't believe any water intrusion will cause damage.

 

[pwa2003]

I measured the gap, and although it varies, it's roughly 3/16" wide.

 

[MAPR-Austin]

I measured the gap, and although it varies, it's roughly 3/16" wide.

Equally if not more important is the depth of the joint, and that it is a true separation between the coping and the deck.

 

[pwa2003]

Here is a picture from "Concrete Deck Pouring Day"... They poured the concrete OVER this exposed edge of the Bond Beam (about 1-1/2" - 2" lap) and then "saw-cut" in portions to achieve the gap to the travertine... TFP articles point to this as an IMPROPER installation. And now I'm wondering whether they sawed through the Bonding wires? There is one wire on each side of the pool. Our "gap" between coping & decking is roughly 3/16", which is too small based on the opinion of TFP members. It seems my dilemma has grown beyond which sealant to use.

Any suggestions?

 

[MAPR-Austin]

You will want to have an equipotential bonding test done to make sure the bonding grid is intact. If not, they will have to take up some deck to make it right but it can be done. This should be an immediate requirement as it is a safety issue.

They either cut through the bonding wires or didn't cut deep enough to separate the coping from the deck. Can you stick anything into the joint to see how deep it is?

My guess is when they ran the saw they did not run the saw through the corners so a little triangle of concrete is still touching the travertine - is all of the damage in the corners? Sealant wouldn't solve this problem.

Deck sitting on that lip can be a problem but is not guaranteed to be. That area of concrete is only as thick as the travertine coping - maybe 2"? Definitely not the best practice.

As far as options they could come and saw cut a proper joint. That will at least stop deck movement from damaging the travertine. They could conceivably cut it deep enough to separate the edge of the bond beam under the deck, but again I don't know if that is necessary. They could take out a ribbon of deck all the way around the pool, fix the bond beam issue by cutting it off or putting on a wider travertine, check the bonding wires, and repour the ribbon.

It will largely depend on how much leverage you have and how effectively you use it.

 

[pwa2003]

Piggybacking off of my thread about the sealant, I'm now thinking I want to remove the past mistakes made by the GC & Concrete contractor. I've attached photos. As stated in previous "sealant" thread, my coping was too small to cover the bond beam and the concrete contractor poured over the Bond Beam by about 2", and had to "saw-cut" a relief gap. Instead of yearly band-aids to fix broken coping tiles, I think I may want to remove ALL the 12" wide coping and replace it with 16" wide coping. To do this, I would need to saw-cut back & remove about 4-4-1/2" of the inner perimeter of concrete decking. That would clear the deck from the bond beam and provide a larger "sealant" gap.... Seems like a cumbersome task, but one hurdle is that the existing relief cuts in the deck would then be misplaced... and the newly cut corner would be the stress point that would see the possible deck crack initiated. Assuming I don't know much about concrete crack propagation, if I "diagonal" or "Radius" the new corners, would that remove the stress points... and therefore reduce the chance of deck cracking?

 

[pwa2003]

You will want to have an equipotential bonding test done to make sure the bonding grid is intact. If not, they will have to take up some deck to make it right but it can be done. This should be an immediate requirement as it is a safety issue.

They either cut through the bonding wires or didn't cut deep enough to separate the coping from the deck. Can you stick anything into the joint to see how deep it is?

My guess is when they ran the saw they did not run the saw through the corners so a little triangle of concrete is still touching the travertine - is all of the damage in the corners? Sealant wouldn't solve this problem.

Deck sitting on that lip can be a problem but is not guaranteed to be. That area of concrete is only as thick as the travertine coping - maybe 2"? Definitely not the best practice.

As far as options they could come and saw cut a proper joint. That will at least stop deck movement from damaging the travertine. They could conceivably cut it deep enough to separate the edge of the bond beam under the deck, but again I don't know if that is necessary. They could take out a ribbon of deck all the way around the pool, fix the bond beam issue by cutting it off or putting on a wider travertine, check the bonding wires, and repour the ribbon.

It will largely depend on how much leverage you have and how effectively you use IT

Yes, your assessment of the corners is spot-on. The broken travertine is limited to the corners and in each of those corners, there is UNREMOVED concrete--- complete with the radiused saw-blade profile. As I have been removing these broken tiles, there is evidence of the sawcut that created the gap. It wasn't my job to make sure the concrete sub did his job properly. It was supposed to be part of the GC's job... but they were largely AWOL during the entire process--- only visiting for minutes at a time to collect payments. After 13 months of their negligence & incompetence, I hired an attorney to FIRE them. I'll have to circle back with the lawyer to see what cards I have left to play insofar as making them pay for their mistakes.

Yes the portion of the concrete deck that laps over the bond beam is about 1-3/4" thick (1-1/4 coping tile plus about 1/2" of mortar. As I have removed some of the broken tiles, I have noted that the saw cut varies wildly.. Some of the saw cut goes into the bond beam-- probably 2-2-1/2 deep from the deck surface, and other places, it's only about 1" deep and doen not penetrate the bond beam at all. I have photo documentation of where (roughly) the bond wires are. I can stick a depth guage in those locations to try to verify the saw-cut depth.

If you can, I may need a expanded explanation of this equipotential bonding/grounding check and whom I should call to do that. Thank you.

 

[ajw22]

No one can predict where concrete will crack. The only sure thing is that concrete will crack.

 

[MAPR-Austin]

I use a licensed electrician for bonding tests, might have to call a few to find one who is experienced. They will put leads on different metal items in and around the pool and check the resistance between them to verify that they are all bonded to the same loop.

I think you will be fine cutting the corners diagonally and it will look good, but make sure your contractor can make the cuts correctly. With the deck already being poured and not being structural I don't know that it will make a ton of difference other than aesthetically.

 

[pwa2003]

OK-- I think this may be an acceptable solution. Please see photos. All the local experts I asked said that having the concrete deck poured onto thw bond beam and having such a small (or no) expansion gap is a problem waiting to happen. Cutting the deck back (without damaging the bond wires) seems to be a given now. So my "sealant" issue has grown into a larger remodel. I found a complementary natural gray stone that I can use to create a "strip border" to fill a 5" gap that I think will do the trick. My Guesstimate is that the concrete rests on the bond beam by 2 - 2-1/2 inches, so a 3" cutback would be the minimum. Anything over that just increases the filler piece and incrementally reduces the heaved condition of the concrete deck. I'm interested in any community opinions on whether I should relpace soil & pack any "drainage-type" material in the soon-to-be exposed portion between the bond beam & freshly cut back concrete deck.... and the best products for sealant gap that I can add sand to to make it look like grout

 

[MAPR-Austin]

The more I look at it the more I feel like I would want the stone to end right at the edge of the existing bond beam. I don't like the stone hanging off the edge of the concrete, even if you put compacted material there it will be nothing like solid concrete. Maybe anchor some reinforcement into the bond beam and pour a tiny footer there?

But if you are comfortable with it, it looks like the most elegant solution so far.

Beneath the sealant you will want a 4"x.5" strip of expansion material with the tear away section on top. I adhere this to the concrete slab - dont use nails!

 

[pwa2003]

The more I look at it the more I feel like I would want the stone to end right at the edge of the existing bond beam. I don't like the stone hanging off the edge of the concrete, even if you put compacted material there it will be nothing like solid concrete. Maybe anchor some reinforcement into the bond beam and pour a tiny footer there?

But if you are comfortable with it, it looks like the most elegant solution so far.

Beneath the sealant you will want a 4"x.5" strip of expansion material with the tear away section on top. I adhere this to the concrete slab - dont use nails!

Thank you. Yes, I was wondering about a narrower strip of stone too. Although I didn't measure it everywhere, the Bond Beam was about 12-1/2" wide, but it could be more, could be less-- I don't believe any great care was taken to have a consistent shell thickenss beyond whatever minimum they felt they needed. The coping hangs over into the pool by about 1-1/4 - 1-1/2, so there is about 2" wide of leftover of Bond beam to "grab" onto by any mortar bed that supports the stone... could be as much as 2-1/2". To get the min 1/2" clearance from the bond beam to the concrete slab, the saw cut will need to be at least 3"... So in theory, I could use a smaller 2" wide strip to fill a 3" cut... the 2" strip will be supported by at least 1-1/2" of Bond Beam. I spoke to a friend that can get me the stone and he said that "chopping" a 4" wide stone strip was tricky enough, so I doubt chopping 2" wide strips of stone ( I think "Silver Mist" would be the stone) is possible. They'd have to be sawcut. And the other issue with a narrower cut in the concrete is if they cut through a bond wire, IDK if they'd be able to find (or have room to find) any rebar to grab onto to re-establish the grounding... I wonder if we could just drive a grounding rod into the soil and attach to that instead. But even that won't be easy-- once you get down about 5', it's solid Limestone, so any rod will need to be driven at an angle, and in a very narrow cavity. There's still a labor shortage in my area so although I may contract with a remodeler that knows his stuff, I may wind up with a day-laborer that I wont be able to communicate with and may not understand the delicate nature.

And thanks for the tip on the expansion material "strip". That works better than the backer rod?? I looked it up..... I was wondering how one would keep the mortar from the stone install away from the deck slab & maintian a positive 1/2" min joint. -- an adhesive foam strip would do it. And that strip stays in permanently?

 

[Bperry]

Thank you. Yes, I was wondering about a narrower strip of stone too. Although I didn't measure it everywhere, the Bond Beam was about 12-1/2" wide, but it could be more, could be less-- I don't believe any great care was taken to have a consistent shell thickenss beyond whatever minimum they felt they needed. The coping hangs over into the pool by about 1-1/4 - 1-1/2, so there is about 2" wide of leftover of Bond beam to "grab" onto by any mortar bed that supports the stone... could be as much as 2-1/2". To get the min 1/2" clearance from the bond beam to the concrete slab, the saw cut will need to be at least 3"... So in theory, I could use a smaller 2" wide strip to fill a 3" cut... the 2" strip will be supported by at least 1-1/2" of Bond Beam. I spoke to a friend that can get me the stone and he said that "chopping" a 4" wide stone strip was tricky enough, so I doubt chopping 2" wide strips of stone ( I think "Silver Mist" would be the stone) is possible. They'd have to be sawcut. And the other issue with a narrower cut in the concrete is if they cut through a bond wire, IDK if they'd be able to find (or have room to find) any rebar to grab onto to re-establish the grounding... I wonder if we could just drive a grounding rod into the soil and attach to that instead. But even that won't be easy-- once you get down about 5', it's solid Limestone, so any rod will need to be driven at an angle, and in a very narrow cavity. There's still a labor shortage in my area so although I may contract with a remodeler that knows his stuff, I may wind up with a day-laborer that I wont be able to communicate with and may not understand the delicate nature.

And thanks for the tip on the expansion material "strip". That works better than the backer rod?? I looked it up..... I was wondering how one would keep the mortar from the stone install away from the deck slab & maintian a positive 1/2" min joint. -- an adhesive foam strip would do it. And that strip stays in permanently?

I suspect the full depth strip would prevent rocks or other stuff from getting between the deck and your new mortar bed, which would negate all the work being done.