Sealant or grout between coping and waterline tiles?


Well-known member
Jan 30, 2018
I am currently doing my waterline tiles. The coping is limestone glued to the concrete pool shell. The shell extends beyond the coping so the coping and pavers beyond are effectively locked together.

I am deciding whether to grout the 5mm gap between waterline tiles and pavers, or to use a flexbile sealant. I like to grout wherever possible as sealants are messy and they fail over time. I have seen hardgrouted pools do fine, however I have also seen coping dislodge and take the waterline tiles with it, meaning not just a coping repair, but a tile repair too.

What is the consensus here as to the correct detail?


Well-known member
Jan 30, 2018
Our setup is is like this:


There is no expansion joint until beyond the the pool shell. The pavers overhang the pool by 30mm.

It is similar to this situation which is recommending no grout between tiles and cantilevered edge.


Here is another version:


The consensus in these details seems to be to use flexible material...
Last edited:


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I don’t buy that the expansion joint is where you point. The deck is cantilevered along the dotted red line. Your construction should do the following…

A “decoupling” expansion joint should extend across the entire width of the top of the bond beam to allow the deck to move independent of the pool shell. This joint can be created with a 4mm plastic sheet or 2 layers of roofing felt underlayment.

It is very important that the waterline tile is installed after the deck is placed so there is no chance of the deck expanding and popping off the tile (see tile placement in the diagram). The tile can be grouted as usual but the top joint between the deck and tile should be filled with a flexible sealant that is not silicone based.
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