2 years ago I had new laminate floor installed by "professionals". The floor guys put down some leveling compound over a few areas. The thickest layer of this compound was in an area next to and exterior sliding door. All was good for at least a year. But then a buckle happened. I had been trying and trying to get a pro to come and repair it (including the company that had installed it). Nobody would commit. So last weekend I DIY disassembled the laminate, the pad and the moisture barrier and discovered this!!
So the leveling compound has managed to "bubble up", stretch while doing so, harden into the warped shape and then stay that way until I dove in.
What the berk, over?
What caused this? How do I fix it?
I have no real idea. Maybe moisture coming through the concrete floor?
Does the floor really need the float? I guess it would be a tiny bit sloped, but it's not like there is a drainage concern.
I just keep thinking it must be some sort of expansion/contraction deal.
Years of doing flooring. I've never seen anything like that. But, then... it is in California. 
If and when you find out, please post.
I'm having a really, really hard time imagining how there isn't water intrusion involved there somehow.
"Exterior sliding door" is my second clue right after the horrible warping.
^^^^^^^
What he said. Is the slab moist ever?
I put down ~300 Sq. Ft. of engineered maple flooring in my previous house. California-slab foundation-right next to a sliding glass door, and had no problems with it for the six years I lived in the house and the four years it was a rental until being replaced for unrelated reasons.
Based on internet research, I taped down several air tight one foot squares of celafain and let them sit for several days to test for moisture...I had none.
I didn't need to level my slab but I did put down one foot square peel and stick linoleum tiles that I got from HomeDepot for $0.29 each as their sub-straight was literally made of tar. Nobody said to do this but I thought, what the heck, $85 gets me what has been keeping boats water tight for centuries and the glossy top made any high or low spots super obvious.
On top of the tiles, I put down high quality aluminum backed padding and used its corresponding high quality aluminum backed tape; no problems with warping, squeaking, etc..
I'm thinking along the same lines as Aircooled "are you sure you need to level?"...is it a constant slope or at least round off gradually over a large distance?
I also agree with Streetwiseguy, given the proximity to the slider, you've probably got water intrusion coming from it so patio drainage away from the house and good caulking all around will likely be required.
I'm gonna vote for vapor intrusion through that crack in the slab under your leveling compound.
The leveling compound did not bond to the slab. If the slab was green when the leveling compound was installed it would have caused this. Basically, it's been that way since it was new, and the leveling compound was bonded better to the laminate flooring than the concrete.
Use a crack membrane first on the crack, and prime the slab. Install leveler as needed, then reinstall the laminate.
You have ZERO bond between the leveling compound and the concrete.
Possible causes: Water or vapor intrusion now, moisture in the slab initially, dust on the surface of the slab initially, or crappy leveling compound.
I know you said all was well for a year, but it wasn't. There was never a bond.
Yeah, that sure looks like a moisture problem and the crack in the concrete hints that there's more going on there than just a poor threshold seal on the door..
Was that an outside porch that later got enclosed?
Could be there is no vapor barrier under the concrete slab.
House was built in 70's so yes there is NOT a vapor barrier under the concrete slab. There was/is however a vapor barrier on TOP of the leveling compound and then the foam pad and then the laminate. Most of the areas where the laminate exists do not have leveling compound and are sitting directly on the old slab. They are not buckling. So this weird E36 M3 is either related to the proximity to the exterior sliding door or to the greater thickness of the leveling compound (or both). The top of the slab was sanded by the install crew 2 years ago, then they applied the leveling compound. But they did NOT let it cure for several days before install. And they did not prime or prep the top of the slab other than to maybe grind it a little. The vapor barrier, pad and laminate went on within a day of the application of the leveler.
A vapor barrier on top of the leveler is useless for this problem.
The moisture comes from under the slab. That vapor barrier protected the laminate from the vapor, but it did nothing to separate the leveler from the vapor.
The problem is the bond between the leveler and the concrete. It's not a laminate problem.
There are a bunch of different leveling compounds and they're not all moisture tolerant and even ones that are can only handle so much water. The first thing you need to do is determine if you've got a moisture problem and how bad it is. You also need to find out what's up with that crack. It could be nothing but it could also be an indicator of a significant issue. If, for example there's a void under the slab that fills up with water under some circumstances then you're not likely to fix that from the inside.
Perhaps some pictures of the outside of the house around that door would help us figure out what's going on.
Hard to tell from a pic but I'm pretty sure that patio is sloped back to the house too
You have California style eaves with no gutters, then a hard surface on the exterior flush with the finished floor.
Water comes off that roof, and yes it gets under your door. No doubt.
Not necessarily a problem, but a contributing factor.
Before you do any repairs at all, go pick up a slab moisture test kit and check that slab.
But keep focused on the fact that you had ZERO bond with the floor. That leveler should have left SOME spots of residue that needed to be chipped up.
Zero bond means it was NEVER right. Most likely there was moisture in the slab when they started, and then they used a leveler that was not compatible with moisture.
So, you seal what's there, caulk the bottom of the door, membrane the crack, prime it, and install a proper leveler that is compatible with the moisture.
Then decide if you need gutters.
SVreX (Forum Supporter) said:
You have California style eaves with no gutters, then a hard surface on the exterior flush with the finished floor.
Water comes off that roof, and yes it gets under your door. No doubt.
Not necessarily a problem, but a contributing factor.
Before you do any repairs at all, go pick up a slab moisture test kit and check that slab.
But keep focused on the fact that you had ZERO bond with the floor. That leveler should have left SOME spots of residue that needed to be chipped up.
Zero bond means it was NEVER right. Most likely there was moisture in the slab when they started, and then they used a leveler that was not compatible with moisture.
So, you seal what's there, caulk the bottom of the door, membrane the crack, prime it, and install a proper leveler that is compatible with the moisture.
Then decide if you need gutters.
I agree with all of this but I'd also plan on adding gutters just because there really should be some. Most of my experience with buildings is in Upstate NY and doesn't necessarily apply in California but that whole patio and interior space on the same plan and seemingly the same slab seems problematic to me. I don't know how big an issue it is but clearly proper caulking is going to be important.
It's worth noting that SVreX does this stuff for a living whereas I'm just an old mechanical engineer who's been responsible for a lot of buildings over the years so I'd give him more credibility than me.
The building slab and the exterior pad/skirt are not the same pour, but you guys are correct they are pretty much on the same grade. For several years I've been using some "splatter shields" made of corrugated (plastic) roof material that I lay across the bottoms of the 3 sliding doors to block the rain. But it's just a cheap ass version of gutters and downspouts. I'll see if gutter contractors are as rare as all the other trades right now.
In reply to APEowner :
Gutters are very unusual in California eaves. That's hard for Yankees like you and me to get our brain around.
The lack of gutters doesn't bother me a lot. They are hard to do on California eaves. Plus, the increased overhang typically moves water far enough from the foundation that they are not necessary.
What bothers me on this one is the hard exterior surface. There are 3 separate sliding doors in that wall- it's super easy for splash to end up going under those doors (which means under the floor). It would have been great to see a continuous drain grate in the patio floor under the eave drip line.
Since that's not there, it's an area of concern.
In reply to Sparkydog :
Right. They are not the same pour, but they are the same grade.
That means there is a joint between them which is letting water under the slab. The suspect crack on the interior slab most likely goes through the exterior foundation stemwall, which means it's a conduit to bring water under your floor in the trouble area.
In reply to Sparkydog :
Note also that the flashing pan on the bottom of your sliding door is LOWER than your finished floor. It is VERY LIKELY this is not sealed to the floor well.
That means the water you are shielding with plastic splash guards IS getting under your floor.
I finally found a pro flooring guy who looked at this thread and also came out to the house on Sunday. He agrees that the leveling compound was not installed correctly. He won't repair it unless he gets to tear the entire floor out, then all of the compound, then prep the slab, prime it, apply new compound and let it properly cure. He also won't let me reuse the laminate so... here goes $5k or so.
Many thanks to you guys for helping me understand what was going on.
In related news - my house sold last week. I close on Nov 4. My stay in SoCal is coming to a close.
If the sun comes in at the angle of the arrow, and if the covering goes wall to wall (no 1/2" gap on perimeter) think it's possible the flooring is expanding with heat?
I've pulled up the base "shoe" and there is proper gap around all the walls of the room. The consensus from the posts is that the leveling compound was not prepped and applied correctly.
In reply to Sparkydog :
in that case re-level the area and put the floor back down and walk away since it's sold
