We are planning a LVP project (our first attempt) that will be going atop an old knotty wide plank (6") floor that is most likely original to the circa 1880 building the apartment is located in. Obvious settling has occurred, with on large area that is depressed a good 1/2" or more. From our first looks at installation guide videos, getting as solid a foundation as possible seems key to making this a project a success. The existing flooring has many gaps in between floorboards, with some that have been filled with various things over the years that are still holding, lots of other areas are loose or open. Our plan was to fill every opening, and use some subflooring for the recessed dip, so we can use a leveler to get a level foundation to begin with. Here is what the floor looks like for reference. Should we use a crack filler for the gaps and cracks (maybe with rope in the bigger ones as a base) to prep for putting down the self-leveling mix next? Seal it before self-leveling? New to this, so open to hearing all advice and suggestions on the project. We will probably have more questions as we proceed, but wanted to start with wrapping our heads around step one.
