Building up small area for a threshold piece

Hello, I recently put down laminate flooring in my living room which is on a concrete slab. There is a sliding door that leads to the outside. The problem is, the concrete slab dips below the footer, and I couldn't get the laminate flooring up to the door. Now there is about a 6 in gap, that's on average 3/8" inch deep. I made a transition piece out of wood to fit on top of it but I'm having the following problem. The gap I need to cover is not level in both the x and you axis. So I can't really shim it up to be even with the laminate flooring.

Could I use thinset or something to build this up level (about 3/8") so I can lay my transition piece down flat? Or is there a better way I'm not thinking of.

Thanks for the help

 

Welcome to the forums. From what you describe, this sounds like a job for self leveling compound. What's the deepest deficit?

 

I would say probably less than 1/2". I never worked with self leveling compound before. Is it viscous? Or will I need to build a container so it doesn't leak under the laminate flooring?

 

Can you post a picture so we can see what your seeing?
Sure would help to figure out what your talking about.