Falling grout where fiberglass meets bullnose coping

tech135797531

Member
Jun 14, 2019
23
FL
I have 2 year old fiberglass pool with 3" bullnose coping going over the edge and down. I do not have any tile, I like this look better. The issue is that some of the grout under the coping is falling off. Yes, I could regrout but I feel like it will have the same fate even if I get the right level of moisture (I assume that the builder put it on too wet). So I'm leaning towards some sort of caulking.

I've read numerous topics here where people were asking for similar advice, but it's all gunite pool/tile not coping/fiberglass. I've seen advice for Vulkem 116 and people were told to never use 100% silicone because they could never use anything else. Is this my case as well? Is there anything better than Vulkem 116? I've seen a suggestion for DECK-O-SEAL ONE STEP – Polymer-Based Sealing Compound but it seems to have pretty low reviews online and it's twice the price.

So to be clear, the grout under the bullnose coping, where the coping makes an edge with the fiberglass wall is falling off and I want to fix it. Any advice? Thank you!
 

jamjam

Well-known member
Jun 25, 2020
620
NY
Pool Size
25000
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Vinyl
Chlorine
Salt Water Generator
i just used sikaflex polyurethane sealant to seal under my coping stones where they meet my liner track - it would be a similar application for you where it meets the fiberglass in yours - so far so good.

this is what i used
 
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Poolguy2021

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Jun 2, 2021
21
Canada

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jamjam

Well-known member
Jun 25, 2020
620
NY
Pool Size
25000
Surface
Vinyl
Chlorine
Salt Water Generator
Sure- I’m away until Saturday, though.
 

Texas Splash

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LifeTime Supporter
Jun 22, 2014
31,721
Texas, San Antonio/Marion, South-Central Area
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PG21, I'll also tag @jimmythegreek for his quick thoughts. My situation is like yours after about 8 years, and there may be other concerns not only for something that works well cosmetically, but also that is reliable to bond with the existing mortar that is still sound.
 
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tech135797531

Member
Jun 14, 2019
23
FL
Just wanted to report back. I've just redone it with sikaflex polyurethane sealant and it looks pretty good. We'll see how long it lasts. This stuff is pretty sticky. I ended up draining a few inches of water and running painters tape all the way around before caulking. My only other long term concern is cleaning it over time but we'll see how it goes. At least there won't be any water getting under the coping. And one more thing to mention...before applying the sikaflex, I went with a small screwdriver and took out all grout that was a bit loose. So the grout I had left was the hard stuff that wasn't going anywhere. And then when I caulked, I caulked over everything, a continuous seal. I hope it was the right approach, only time will tell.
 
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jamjam

Well-known member
Jun 25, 2020
620
NY
Pool Size
25000
Surface
Vinyl
Chlorine
Salt Water Generator
You. Here is my coping. Im hoping to have this fixed.
Since you don’t have a significant cantilever you may want to do a bit of research on a sealant with higher UV protection - the sika can yellow slightly if exposed to direct constant sunlight - also you might want to look into something that comes in grey to match your coping since nothing will be hiding it.
 
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Poolguy2021

Member
Jun 2, 2021
21
Canada
Since you don’t have a significant cantilever you may want to do a bit of research on a sealant with higher UV protection - the sika can yellow slightly if exposed to direct constant sunlight - also you might want to look into something that comes in grey to match your coping since nothing will be hiding it.
I am looking at possibly having glass tiles added. Not sure yet about what we will do.
 

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