We are having LVP installed and I'm removing the old flooring to save some money. Most of the flooring being removed is wood but the bathroom and a small area by our back door are currently tile. I removed the tile from the backdoor area and I'm using my oscillating tool to scrape off the mortar. My question is how clean does the surface have to be for the LVP installation? Obviously you don't want any thick pieces left but there are some very thin spots that just won't come up. When I say thin it's basically smooth to the floor. Any insight would be appreciated!