How Thick Should my Poly Void be behind the coping

wxman18

Member
Oct 17, 2018
9
Madison
I'm going to order poly void to use as expansion joint between my travertine coping and the concrete deck. Just wondering how thick I should go. Thanks. Getting closer to being done.
 

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Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,439
Bedford, TX
18,

All the pools I have seen, including mine, have a 3/4" gap between the coping and the deck.. Filled with Poly void and some type of caulk on top of that..

Let's see if we can get some of our other members to chime in...

Thanks for posting,

Jim R.
 

galowbraw

Well-known member
Jan 11, 2019
94
SPRING/Texas
Not to hi-jack your thread, but do some PB's make the gap smaller and not use anything? Is there a benefit to this besides dirt/junk getting in this crack? Is it strictly aesthetics?

The Deck-O-Seal website and how-to videos look legit and great Jim!
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,510
Northern NJ
Not to hi-jack your thread, but do some PB's make the gap smaller and not use anything? Is there a benefit to this besides dirt/junk getting in this crack? Is it strictly aesthetics?
The pool with it’s coping on top needs to move independant of the deck. If the deck is hard against the coping something is going to crack. The expansion joint needs to be filled with flexible foam and caulk.

Expansion Joint Caulking Around Inground Swimming Pools
 
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wxman18

Member
Oct 17, 2018
9
Madison
I saw on a previous thread that a 1/4" joint will work and the reason some are 3/4" has to do with the fact many forms that are used to pour the concrete are 3/4" thick. I would prefer to use 1/4" because it will look better and require less caulking. I'm probably going with the deck o seal.
 
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galowbraw

Well-known member
Jan 11, 2019
94
SPRING/Texas
I saw on a previous thread that a 1/4" joint will work and the reason some are 3/4" has to do with the fact many forms that are used to pore the concrete are 3/4" thick. I would prefer to use 1/4" because it will look better and require less caulking. I'm probably going with the deck o seal.
Keep us updated on process and post before and after pictures if you can!

Good luck WX.
 
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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,510
Northern NJ
I saw on a previous thread that a 1/4" joint will work and the reason some are 3/4" has to do with the fact many forms that are used to pour the concrete are 3/4" thick. I would prefer to use 1/4" because it will look better and require less caulking. I'm probably going with the deck o seal.
Problems Due to Concrete Decks

The most important bit of information to remember is the expected expansion in concrete caused by temperature change. Between the heat of summer (pool deck surface at 130º to 140º) and the dead of winter (pool deck surface at 30º to 40º) we can expect at least a 100º temperature change. The critical number to remember is that a 100 foot wide section of concrete will expand approximately 3/4 of an inch with a 100º temperature change. The expansion in lesser widths of concrete can be easily determined by proportioning the 3/4“ per 100 feet. The force of expanding concrete is very high and can easily shear off the coping or bond beam without properly installed isolation joints.


A 1/4” expansion joint may protect you if you have less then a 30’ run of concrete deck. I would rather have a wider margin and make it at least 5/8”. The risk of failure is too high to cut it close.
 
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vegas27

Bronze Supporter
Sep 28, 2018
28
Las Vegas NV
Please pardon my ignorance, I’m not trying to hijack the thread. I’m new to this and don’t want to mess up my build. I’m doing an owner build and would like to know, if I have to put the expansion joint or foam on my pool deck and coping even if it’s travertine coping and decking ? Thanks in advance
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,510
Northern NJ
Please pardon my ignorance, I’m not trying to hijack the thread. I’m new to this and don’t want to mess up my build. I’m doing an owner build and would like to know, if I have to put the expansion joint or foam on my pool deck and coping even if it’s travertine coping and decking ? Thanks in advance
You need to understand that the pool is a separate structure from the deck. They need to be able to move independently. They will have different thermal expansion through heat and cold cycles and ground can shift over time.

If you tie then together through the coping and deck touching you will eventually get cracks. The cracks could show in the deck or they could be in the pool.
 

shannnon

Active member
Jun 30, 2018
30
St. George/UT
UPDATE I went with 1/2" Poli Void. The top of the foam peals back after you pour the concrete and you then fill that void with caulking. I used spray adhesive on the back of the coping and the edge of the foam to get it to stay in place.
This looks amazing. We are owner builder also and are ready to pour concrete decking next to our flagstone coping. I am just now learning about expansion joints. Where do you get this material? Did you install it yourself or did you have a concrete sub do it?