Cantilevered concrete coping

[Drew80]

We're working on the design of a new build in Austin, TX, and we're trying to decide what type of coping we want. We're going for a more modern look, so we're toying with the idea of cantilevered concrete right up to the edge. I have a few questions:

1. Do we need to use any specific type of concrete?
2. Do we need an expansion joint with cantilevered concrete? I've looked at tons of pictures and watched a few videos, and I often don't see expansion joints. Some pictures below.
3. If we don't put in an expansion joint, how do we keep the deck from cracking?

These are the pictures I'm looking at (some are cantilevered stone).

http://dev.watercolorspools.com/wp-content/uploads/2015/10/cantilver-concrete-resized-600.png
http://www.ableok.com/hs-fs/hub/327303/file-506401469-jpg/Franks_Images/Cantilevered_concrete_coping_2.jpg?t=1472688665966
http://www.foreverpools.com/wp-content/uploads/2014/03/Cantilever1-1030x686.jpg
http://www.foreverpools.com/wp-content/uploads/2014/03/IMG_1957-1030x686.jpg

 

[GaryT58]

1. Don't think so, they used the same concrete for ours as the rest of the decking.
2. We do not have one. The edge is only about 3" over the pool, so not sure how or why would need one.
3. Again, not sure need it. We do have expansion joints around the decking in general - which extends through the cantilever.

That said, we are very happy we chose it for our pool.

 

[Drew80]

Thanks for the reply Gary. Do you have some pictures to show me what you're talking about? I'm specifically concerned about cracking of the decking if we extend it up to the edge of the pool. The first and second pictures I posted really show the look that we're going for.

 

[GaryT58]

Here is how it looks from above (the silver track is for my auto-cover).



Here is what it looks like at edge:



and from the water side:



So can see the expansion goes through it like the rest of my pad, but not parallel to the pool itself.

 

[Veccster]

Definitely get the cantilevered concrete edge. It's not cheap because they have to buy additional styrofoam molds to hold the concrete in. It is the same concrete as the rest of the pad - though we are getting a colored border (something else to consider). It's not built yet but here is the gist...

 

[Drew80]

Can someone explain to me why we don't need an expansion joint parallel to the pool edge? Won't that cause the decking/coping to crack if/when the ground expands?

 

[GaryT58]

It expands the same as the rest of the decking. I do have some parallel to pool, just not pictured, since my pool deck is pretty wide. The only reason I could see to need it as part of cantilever is if the material was a different type to the rest of the deck, or poured separately.

 

[Drew80]

Aha, that's the missing piece. Thanks!

 

[bdavis466]

Both traditional coping and cantilevered coping MUST have an expansion joint. Traditional coping has the expansion joint between the coping and deck, cantilevered coping has the expansion joint between the decking and the top of the bond beam.

The whole purpose is to prevent the deck from pushing on the pool shell as it expands and contracts.

Take a look at this thread:

Expansion Joint vs. Control joint between cantilever coping and pool deck

 

[chiefwej]

I have a cantilevered pool deck. No expansion joint is required because there is a slip joint at the top of the bond beam where the deck sets on top of the pool shell. The deck is able to move independent of the pool without damage to either.

 

[Drew80]

Thanks for all the replies. Very helpful.