We’re just getting started renovating our pool and deck. We increase the size of our concrete deck and plan to wet mount 1” thick EverBlue porcelain pavers on top using Ardex thinset. Wondering how we should handle the existing expansion joints and connection between new and old concrete. If we “honored” all of those joints, we’d have a ton “soft joints” (ie, caulk instead of grout). Not only would the pattern be all broken up but the the concrete pad has alll sorts of curves. One thought was to use a ditra membrane over the joints and liquid membrane elsewhere. Any thoughts suggestions. We live near Boston and don’t want to have have a ton of crack telegraphed through the pavers in a year or two. Thanks
Porcelain paver overlay on concrete. What to do with joints?
- Thread starter BigLebowski
- Start date
Anywhere there’s a joint in the underlying concrete is where a new crack will form in whatever is bonded over it. It’s a designed weak spot. Not much you can do other than tear it all out and repair it.
Do you know if dowels were set into the old slab before the new one was poured?
Why do you want to wet lay into thinset? With multiple distinct slabs and especially with those sweeeping curves, I would think that you need to be totally un-coupled from the substrate. Those slabs are essentially the same thing as a well compacted subgrade for laying pavers traditionally. I got curious and looked up “everblue pavers” (I’m a specs nerd) and their install manual is pretty clear that you absolutely can lay pavers into a light sand course over concrete (making appropriate considerations for drainage). If you go that route, you wont be glued down in thinset across any of the cold joints or expansion joints.
Those look like big 18” or 24” pavers. Uncoupled, I think you’re ok to lay a pattern across joints. My concern would be limited to vertical heaving, but that will be spread out across the length of the paver. You might ask the mfg if you should slightly increase the width of the sand joint to allow for a little more play. I don’t know how much you’ve increased the size of the existing pavement, but if its substantial I’d also think about waiting a season to allow the ground underneath time to adjust to the weight of the new slab and also equalize moisture content with the existing slab (clay soils in your area?). Next year you can come back and lay a level sand course across everything knowing that you’ve accounted for as much settling as you can stand to wait for. (I’d probably skip this if the slabs were doweled).
Personally, I’d think twice about a “tile approach” using thinset in this instance. Ditra does make a very specific outdoor uncoupling membrane that is designed for patios to be self draining, and somebody well versed in the product may be able to evaluate its potential here. That person isn’t me. Also, ARDEX makes great products. I really like them. Read up on the substrate moisture specs for the specific product you’re looking at using. When I was looking at using some last, I learned that some of them are designed to be used on green concrete. Others require a more substantially cured slab.
I assume you are working with a reputable local contractor who knows flat work and your region (not a Craigslist jack of all trades). Ask questions. Heed advice. Agree on a plan. You’re paying for experience.
Why do you want to wet lay into thinset? With multiple distinct slabs and especially with those sweeeping curves, I would think that you need to be totally un-coupled from the substrate. Those slabs are essentially the same thing as a well compacted subgrade for laying pavers traditionally. I got curious and looked up “everblue pavers” (I’m a specs nerd) and their install manual is pretty clear that you absolutely can lay pavers into a light sand course over concrete (making appropriate considerations for drainage). If you go that route, you wont be glued down in thinset across any of the cold joints or expansion joints.
Those look like big 18” or 24” pavers. Uncoupled, I think you’re ok to lay a pattern across joints. My concern would be limited to vertical heaving, but that will be spread out across the length of the paver. You might ask the mfg if you should slightly increase the width of the sand joint to allow for a little more play. I don’t know how much you’ve increased the size of the existing pavement, but if its substantial I’d also think about waiting a season to allow the ground underneath time to adjust to the weight of the new slab and also equalize moisture content with the existing slab (clay soils in your area?). Next year you can come back and lay a level sand course across everything knowing that you’ve accounted for as much settling as you can stand to wait for. (I’d probably skip this if the slabs were doweled).
Personally, I’d think twice about a “tile approach” using thinset in this instance. Ditra does make a very specific outdoor uncoupling membrane that is designed for patios to be self draining, and somebody well versed in the product may be able to evaluate its potential here. That person isn’t me. Also, ARDEX makes great products. I really like them. Read up on the substrate moisture specs for the specific product you’re looking at using. When I was looking at using some last, I learned that some of them are designed to be used on green concrete. Others require a more substantially cured slab.
I assume you are working with a reputable local contractor who knows flat work and your region (not a Craigslist jack of all trades). Ask questions. Heed advice. Agree on a plan. You’re paying for experience.
Appreciate the detailed advice. We are having the pool redone and the gunite level raised about an inches and a new granite coping installed. The new section of the deck was attached in the fall with a ton of steel dowels. Overall, the new deck should be about an inch higher, but it shouldn’t really matter much with the higher gunite. Water level will stay the same for the skimmer. The reason we didn’t go with dry laying the pavers (but could still switch) are:
1. I was told the pool cover anchors won’t work unless the pavers are mortared in. Maybe it’s possible to screw the anchors in much deeper into the concrete slab so they don’t move. Or, maybe the first set of pavers could be mortared in and the rest laid on compacted sand. Would the transition look ok, especially if we used polymeric sand instead of grout.
2. We were trying to keep the assembly as thin as possible so the final deck height wasn’t particularly high to keep the first step height reasonable. But, it looks like we could get pretty close with sand (maybe 3/8” instead of 1/4”).
3. We were going for a higher end look, it’s a classic, 100 year old property. A few folks have said that the sand base will not hold up well, will have issues with freeze/thaws, and will look sloppy for a more finished property.
We’ve never had a pool before, let alone a standalone house. So any recommendations would be appreciated.
1. I was told the pool cover anchors won’t work unless the pavers are mortared in. Maybe it’s possible to screw the anchors in much deeper into the concrete slab so they don’t move. Or, maybe the first set of pavers could be mortared in and the rest laid on compacted sand. Would the transition look ok, especially if we used polymeric sand instead of grout.
2. We were trying to keep the assembly as thin as possible so the final deck height wasn’t particularly high to keep the first step height reasonable. But, it looks like we could get pretty close with sand (maybe 3/8” instead of 1/4”).
3. We were going for a higher end look, it’s a classic, 100 year old property. A few folks have said that the sand base will not hold up well, will have issues with freeze/thaws, and will look sloppy for a more finished property.
We’ve never had a pool before, let alone a standalone house. So any recommendations would be appreciated.
- Jul 21, 2013
- 65,688
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Use Long Deck Anchors or 9" Pipe Anchors that will go through the paver into the concrete below.
Accessories
The “best” pool cover should be secure with the “best” hardware. Meyco hardware is non-corrosive, solid brass or stainless steel.
meycocovers.com
+1
My opinion: You know what really looks sloppy? Stress cracks, popped tiles, and unnatural joint patterns that telegraph the substrate. Doing paver maintenance isn’t fun, but it is manageable and doable in bite sized chunks. (Also, I suspect they’re speaking to you about a traditional sand bed, not sand over concrete.)
Keep in mind your concrete and your pavers will have different expansion/contraction properties and that same freeze/thaw cycle is going to be imparting opposing forces against any thinset adhesive. Tile work is a much bigger PITA in my opinion, especially if the material has started to weather and you can’t match it.
agjr85
Well-known member
Following as we are looking at doing pavers and I hate to deal with pavers's on sand.
But didn't think about doing a concrete base, then pavers over sand
But didn't think about doing a concrete base, then pavers over sand
You see it more in commercial construction where it has already been specified in the drawings and the guy bidding the job doesn’t have to explain the additional costs and benefits of the concrete.
I have high clay soil content in my region, so my current patio has dips and heaves all over the place. When I redo it, I’ll go this route.
Thanks ! What about mortaring in the first row of pavers (next to the granite coping) so we have something solid to install anchors. And, also mortaring in the last row that abuts the lawn (so we don’t need an edge guard and the sand bed won’t migrate). In between, we could use the sand bed and match the heights and use polymeric sand instead of grout. Is that a good approach?
Bill1974
Well-known member
- Jun 18, 2014
- 675
- Pool Size
- 32000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Your existing concrete doesn't have any cracks which is good. But that is likely because you have ample expansion joints and the slabs are not overly large. I doubt you will be able to bridge an expansion joint and not have a tile crack at some point unless those tiles are free floating in a bed of sand or something. If you don't want to have a pattern that shows the expansion joints, setting in sand or an uncoupling membrane are your only viable options. Do so research into polymetric sand for what is going to work best in your design. At the same time a border of smaller tiles that can be adhered to keep the field tiles in place is probably going to be needed. The smaller tiles can spaced to hide the cold joints and expansion joints and not eventually crack.
You may do as you planned and only have to set some tiles in sand that bridge cold joints and expansion joints. But then you risk joints between the sand set and hard set tiles to take all the movement, as opposed to it being spread out to all the tiles.
if you adhere a boarder tile, leave some openings for water to drain. water will get under the tiles at the joints and it needs somewhere to go. Most paver over concrete slab recommend to put holes in the slab to drain this water. Depending on what material is under the concrete, that could cause localized heaving. Since your concrete is in good shape continue to drain water off the sides.
You may do as you planned and only have to set some tiles in sand that bridge cold joints and expansion joints. But then you risk joints between the sand set and hard set tiles to take all the movement, as opposed to it being spread out to all the tiles.
if you adhere a boarder tile, leave some openings for water to drain. water will get under the tiles at the joints and it needs somewhere to go. Most paver over concrete slab recommend to put holes in the slab to drain this water. Depending on what material is under the concrete, that could cause localized heaving. Since your concrete is in good shape continue to drain water off the sides.