Deck to coping expansion joint sealing

gtemkin

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Jun 7, 2008
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Seattle, WA
I need to select an expansion joint sealant to apply between a concrete deck and granite coping.

It looks like polysulfide rubber has long been used for this and I've found both positive and negative reviews on this forum.

There's also acrylic sealers that have very mixed reviews. Someone who had a failure with this type of material said their solution was to change to SikaFlex sold at Home Depot which I believe is a polyurethane material. The data sheet for that says not to use when exposure to greater than 5ppm of chlorine is expected. Sounds risky for this purpose.

From a historical standpoint I can see why polysulfide products might have been the only solution in the middle of the last century, when that was the only field dispensable rubber available, but since then silicone and polyurethane technologies have become a mainstay of similar sealing needs.

I've looked, but for other than repair materials, I haven't found silicones specifically marketed for deck to coping sealing. If there's nothing wrong with silicones, I was thinking of going with a self leveling variety in which I dust the top surface with colored sand. Any thoughts? Has anyone used silicones successfully?
 

duraleigh

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Apr 1, 2007
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Polyurethane has held up very well for me. It is a bit messy to handle and you have to be very careful (mask it off with tape) handling and applying it....it's messy.

Mine is about 7 years old and just this season showing some signs that it might be approaching time for a redo.
 

gtemkin

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Jun 7, 2008
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Seattle, WA
Good to know about urethane's potential. Have you or anyone else done the dusting with sand to try and coordinate it's appearance? I have acid etched concrete and sand blasted granite. I'm hoping that I could use sand to tone down the gloss of a urethane or silicone. Any tips or tricks?
 

duraleigh

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I think you will find the urethane will not have the gloss that silicone does. Mine looks and feels more like the consistency of a tire innertube
 

gtemkin

LifeTime Supporter
Jun 7, 2008
738
Seattle, WA
Yes, Deck-O-Seal is the major supplier of polysulfide rubber based products. There's nothing wrong with them, however newer sealing technologies, silicones and urethane have overtaken polysulfide in much of the construction and manufacturing industries, where there's a wider choices in performance, application and competitive pricing.
 

kwolfe

Well-known member
Mar 28, 2013
49
Central PA
I am digging up an old thread here, but is it necessary to fill this joint as soon as possible? We put our pool in last year and the concrete guy put a layer of white foam in between the stamped deck and the bullnose brick coping. Is that fine to leave there for this year as well?

I already have enough projects on my list. :hammer:
 

Mongo

Active member
Feb 1, 2013
36
I was the same. I did my concrete slabs surrounding the pool one year, then the next year covered the concrete slabs with stone tile. So all I had was backer rod or expansion joint material in there.

One thing I did get was ants. So having an open joint, watch out for that. Not a huge deal...but they found passages through to the stone dust under the slab and sure enough, they set up house.

When I finally did seal the joint, I used a shop vac to pull any debris out of the joint. Then I used sand to fill the expansion gap to the proper depth. Then if I remember correctly, I used a product called Vulkem 45. A one-part PU, self-leveling product. Gray color. I did have four or five areas where, due to the irregularity of the stone, the Vulkem flowed out of the joint and on to the stone. I let it. It created an overflow film, only a few square inches, maybe a max of 1/8" thick.Then the next day I scored the film of now cured PU with a utility knife and it peeled right up off the stone tiles.
 
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