How do I repair this mess under my removed fireplace hearth yo cove it with my lap flooring?

... " level " isn't the problem here ..

D I Y woodstoves and fireplaces are seldom pretty. Start over - with safety and fire code top-of-mind. John T.

Why did you post twice?

Missing is some crucial information. How close to level with the flooring is what;s there? How thick is the flooring material? Do you have the same flooring material?

I was having problems with the site

How level does it have to be? Just lay a board over the whole thing and put in some wooden spacers so it doesn't wobble. Then use a piece of stripping, lath, in front. to hide the space between what's there now and the board.

It seems wide enough that people may step on the front of it. You'll need to make it firmly attached to the blocks. Construction adhesive??

If you had a book shelf there, it would have a bottom shelf right on the floor almost an incb thick. This won't be much different.

Not level at all. The vinyl plank I have is 8mm thick, and I do have some of that left. I’m just wondering if that mess is sitting on sub flooring. It is over our crawl space.

It looks pretty loose to me. I'd pull a few pieces out to see what's going on down below. Granted, I have the tools and expertise to build whatever framing is needed to create a proper structure to support a floor.

Odds are I would have emptied that area out before I even considered leveling out what's there. It has to be sitting on something fairly solid. It's not supporting itself, not with all those gaps and cracks.

If you'd be willing to dig in a little bit and send some more pictures, we could be more specific as to what to do next.