EXPANSION JOINT FOAM BETWEEN COPING AND PAVERS

grottoguy

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Aug 24, 2014
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NJ
When my pool was built, I was required to keep an expansion joint between the coping and my deck pavers. The joint was 1/4 inch and was filled with foam 4 inch by 1/4 inch (this foam was also required). I have a contractor fixing some stuff and he pulled up the foam and is replacing it with a backer rod and will use Sika Flex on top of the rod. The rod is about 1 inch of depth. Even though the Rod is only 1 inch of depth, my expansion gap is still 4 inches by 1/4 inch. My question is this: To keep my warranty on the shell, I was required to have 1/4 inch by 4 inch foam between the coping and the pavers, but I will no longer have that. Am I correct that the foam was mandated to ensure that my expansion gap was 1/4 inch by 4 inches (i.e., the measurement of the foam) and that the actual presence of the foam was not important. In other words, now that the foam has been removed, I still have the same size expansion gap, but simply no foam (just a 1 inch backer rod).

I am assuming that the expansion gap is what helps prevent the pavers from destroying the pool shell, and that the foam itself was used to establish the proper size of that gap, but that the foam didn't actually help prevent the pavers from destroying the pool shell.

Am I making sense?
 
The foam at 1/4” X 4” is designed to be installed for concrete decking. The concrete can be poured directly up to the foam and the top is perforated to be pulled off prior to the epoxy being installed.
Yes it insures that the proper distance is obtained and that nothing solid gets between the coping and the deck material.
 
He already removed the foam before I realized what was happening. In its place he put the backer rod. My question is now that he has removed it, does it matter? Does the foam itself serve a purpose or is it sufficient that I have an expansion joint that is 1/4 x 4 inches deep.
 
Does the foam itself serve a purpose or is it sufficient that I have an expansion joint that is 1/4 x 4 inches deep.

It is sufficient that you have the expansion joint. Your only risk is if dirt fills in the area under the backer rod.

If you had a gap without the foam and mastic then over time dirt would fill the expansion joint.

Filling the joint with foam with a layer of mastic on top requires much less mastic then if you filled the entire joint with mastic.

The entire gap should have been filled with foam backer rod but I don't think it is worth it to rip out what you have to redo it.
 
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