Your floor is hugely out of level.

Because the drywall touches the floor at some point and then slopes to the deepest fill point, my rough estimate would be that the volume to be filled is a triangular section, but that only cuts the material cost in half. Still a lot of money!

Having done floor leveling on smaller areas in my home, a big issue with that much material needed to level your floor is the labor and time to mix that many bags. Your volume needed is a huge undertaking.

Honestly, I think your best course of action is to hire out the leveling work, bring in a mixing truck on site and pump the needed fill in one shot. Yeah, it will be costly.

Yeah, that may be a good consideration...any idea how much that might cost? I don't even know where to look...

Another option I thought of... I THINK (but not positive) that MOST of the floor is actually lower, like in the corners. Here's a picture of the opposite wall - the gap between the drywall and the floor looks much more consistent, and the drywall doesn't get nearly as close to the floor. So it may be more like a "hump" in that one section of the floor along the wall, rather than totally unlevel all around. So maybe I can just level out the rest of the floor the best I can, and just leave a hump in that one section - so it won't be totally level throughout the whole room but it, but it should be very level at least along the other 3 walls, which is where most of my gym equipment is going to go. I'm just putting a rubber gym flooring down, so I don't think that would be an issue. The downside is that the later down the line if we wanted to convert the room to something else (e.g. sell the house) and put real flooring down, then there would be an issue. Not that I'm expecting to do that anytime soon...

I'd have to confirm that is the case though by somehow mapping out how level the floor is more extensively.

Forgot to attach the picture in the previous post... Still a bit unlevel, but doesn't look as bad to me...

Being 2", I assume the floor is sloped towards a floor drain. That might be something to consider how you laid out your rooms.

You can read the installation directions for the Mapei product you selected. For extending the material application you can add aggregate (which is the case for many self-levelers). Some levelers describe the use of repair mortar or non-shrink grout under them. You can also call Mapei support for technical help, like whether it can be feathered, or using a bonding agent between layers that their instructions do not provide.

I also assume, it slopes towards a floor drain, and it might be a very good idea to leave that slope there, in case, you have any water problems in the future. Put the rubber flooring down on the part, you are actually going to be using your equipment on, and leave the rest of it alone.

I hope I'm wrong but it appears you used untreated wood for the bottom plates framing the walls. If you did your going to end up with rot and stink pouring any kind of cement up against it.

3onthetree and cat_ky - there is no "drain" anywhere, but there are a couple sump pumps (maybe that counts as a drain?). I did check, and this does not appear to be sloping toward them.

3onthetree - interesting regarding aggregate, that is something I did not know about and am now educating myself. So basically, add a layer of gravel or something to help build up the height in low places and reduce the amount of self-leveler I need? I found this: https://cdnmedia.mapei.com/docs/librariesprovider10/line-technical-documentation-documents/extending-slus-with-aggregate.pdf?sfvrsn=de4978c4_4 - looks like I can add pea gravel?

kevin9408 - you are wrong. I used pressure-treated wood all around for the bottom boards. :)

Good to hear you used treated mike, you won't believe how many people don't. My nephew didn't and when I saw it I told him and he said F it. OK then, and inspector caught it and had to rip it out and replace it.

Abandon the self-leveling please. You need a mud-jacker. Some of them use foam these days.

Joseph Corlett, LLC - curious why you suggest mud-jacking over self-leveling. Cost? Will that result in a level floor?

(Keep in mind, I only care about leveling this one room within my basement...my basement is pretty large. This is only about 1/3 of the whole basement)

It's always about cost effectiveness. I can't imagine a mud jacker charging you 6K for this. It may take a combination of the two to get to dead level.

I'd like to use a long level to map out the actual contours of your floor. Grinding may handle some of it. Next, I'd plan out the area where a level space will be necessary.

All - just an update: turns out the floor was not as unlevel as I thought. I ended up hiring a guy to do it (I didn't trust myself), and he was able to cover the floor with about 40 bags.

That being said - I regret hiring that guy, because it didn't come out great - there were "ridges" left where one pour net another. I'm not sure what he did wrong - if he didn't mix properly, or because he used the quick-setting stuff... Either way, the floor is "level", but not as flat as I'd like. If I put down rubber flooring, I can feel/notice spots that are a little bumpy.

I'm going to make a separate post about this since it's technically a different question - but I'm thinking about doing another thin later myself.

i think you will get the best advice if people can see the full history of what has already been advised and attempted. i wouldn’t start a new post.

Jennz9b - I'm certainly open to suggestions here as well. I'll attach some pics here for reference. Basically what I said in the last comment - I asked the guy to come back and fix it, and he tried smoothing it out with some "thinset mortar". Honestly, still not happy with the result - I feel that it should be flatter. If I put down a rubber mat, I can still notice the bumps.

The first three pictures show the ridges I'm talking about. The fourth picture is a spot where there's a "swirl" from one pour meeting another, but IS flat (for reference). The last one shows the result of the thinset mortar.

Looking for suggestions as to how to fix. Would the best way to fix it be to add another thin layer of self leveler? Hopefully I could get away with adding just another 1/8 inch layer (which would be about 10 more bags).

Also, can I pour self-leveler down directly on top, without adding more primer? I believe I heard that self-leveler binds well to itself without primer - although the self-leveler I will be using is a different product than the one used previously - not sure if that matters. (Also, will it bind to the spots with the thinset mortar?)

Listen to Joe on your other post

Check locally for a concrete grinder rental. Ridges should go fast.

So after looking at it more, it think the floor is still not as level as I'd like it to be either...so I think I'm going to do another layer of self leveler anyway.

Does anyone know the answer to my question about whether I need to prime the floor again?