I am installing a laminated wood floor. I first thought the floor was warped but I found out it was where the floor support were mouned to the fireplace for the floor joist. For some reason the support at the fireplace are <1/2" out of level. The floor has a slope until it reaches the first support after the fireplace foundation support. Then the remainder of the floor is level. Should I used leveling compound or should I just not worry. The planks will run parallel to this area.

This is new to me but my plans were to install the underlay laminate foam. The subfloor is plywood. Also the original floor is linoleum and the manufacture said no problem over this but the slant in the floor was different. To install self leveler compound was my plan, I think that is the same as thin set. I'm not sure what the leveling kit and plastic shims are, at least not now. I do have to remove the linoleum about 36" to level the floor if you think this would be wise. As I said the problem is in the way the floor joist at the fireplace is mounted about 1/2" higher than the other floor joist.

Laminate flooring will not tolerate an out of level installation. You will have a bouncing floor and it may sound hollow or clicking when you walk on it. Most flooring includes a leveling kit with plastic shims. You could level the area with thinset but we don't know what your sub floor material is yet. Are you installing a foam sheet under the laminate?