How do I fix this? Prepping subfloor for laminate and baseboards

[MooreB]

Hi everyone, and thanks for your time and advice. I've removed some old parquet and will be installing rigid core laminate in a room. I've checked the room with a laser level, and it's consistently level throughout except for one small area in the alcove near the bedroom door, where it dips 3/8" within about 14 inches of space. I've included some photos to help visualize. I've semi-installed a few rows of flooring, and I already need to push down on the end planks by the door a lot to get them to curve and meet the subfloor near the wall. I'm wondering a few things...

1) Do I need to adjust the subfloor here to level it with the rest of the room? This dip occurs all the way across the top edge of the room. Its a 3/8" difference over in the alcove by the door, and it also happens across the closet. Within about 14" at that end of the room, the floor dips 1/4" as it meets with the wall. I'm not a stickler for things being exact, but this seems like a big dip within a very small space. I can already see in my test flooring that my laminate planks need to curve a bunch to meet the subfloor. I personally don't care about this, unless it's going to create some damage in the flooring later on.
2) If I leave the subfloor the way it is, then install the flooring with a slight curve at the end, will this have an impact on the baseboard when I install them later?
3) If I need to fix/adjust the subfloor before installing the flooring, what should I do? I've researched self levelling compounds, ardex feather finish, etc but I'm not very experienced.

 

[highup]

Flatness is just about the most important part of the installation. These floors are not designed to flex, so if there is a dip or a high spot, every time you step on that area it moves the locking joint. Over time, the joint can break.
That's not an uncommon thing, so I'd spend what ever time it takes to either sand down any high spots and fill the low ones.

 

[highup]

In the first image, you could cut a 1/4" strip of wood an inch wide and nail it next to the wall, then screed some filler between the wall and the beginning of the dip. Some of the guys prefer multiple layers of roofing felt instead of filler. You'd lay successive strips of felt to achieve your height.
A 15 inch strip, a 13 inch strip, 11, 9 etc, making up the ramp.
Inside the closet isn't as important because it never gets walked on. That said, felt would be less messy and it's easier to get consistent in small areas like that.

 

[highup]

Also, tho the Lazer can be quick and easy to do, it tells you that your floor doesn't have any major issues. That said, it's best to get down on the floor with an accurate straightedge, or a 6 ft level and slide it all over the floor in both directions to be sure there aren't any small high spots that you didn't hit when using the laser. The walking areas are obviously the most important.... under the couch, less so.

 

[Maurie Smith]

It sounds like you've got a bit of a tricky flooring situation. Since the dip in your subfloor seems pretty significant, especially in a small area like the alcove, it might be worth fixing it before laying down your laminate. If you leave it as is, you might end up with some issues with your flooring and baseboards later on.

Self-leveling compounds or Ardex Feather Finish could help, but if you're not experienced, it might be best to get a professional opinion or even hire someone to do it for you.