take the chairs to the workshop or garage and sand the leg bottoms until they are flat to the floor (angle) and even, then sand the edges so they are not sharp edges ... slightly rounded. or get a carpenter to do it for you. or a furniture repair and mainenance handyman/shop. then use Chair Leg Floor Protectors. Here is a link that might be useful: chair leg floor protectors

Visual inspection of the ceiling is not perfect. Use some string (kite string?) wrapped around a piece of wood on each end and hold against the ceiling/wall joint. Hold the string so it is not against the ceiling and see if the gap is the same along its lenght. Upstairs you will need to remove the floor and subfloor and fasten 2x4s or 2x6s to the joists to get a level support for the floor. Replace subfloor and then finish floor and you'll be all set.

I just had Karastan SPC installed by an excellent family owned flooring company with a lifetime guarantee on their installation. Their installers are employees, not subcontractors. They honor their warranty. They will rip out and replace an entire floor, hard surface or carpet, if necessary. The plank has a crushed limestone core. They honor it. In one area, I had 125 square feet of Armstrong Alterna removed. This is a glue down tile. They then skimmed the concrete subfloor to cover the residual glue, as they said that walking on the planks could activate the glue. No shortcuts taken. Not with a lifetime warranty. Most of the concrete subfloor is perfectly level. However, one section has a slant like yours. The installer said the the concrete was lower on one side of the poured joints. Noticeably so. He said with these rigid planks, that would not be a problem. I don’t notice any problem walking on the floor. Did you install a quality rigid plank?

Hu-183233286-- We had the floor leveled by Acousti-Level. We had to wait about three weeks to get the work done. On the day of the job they brought in 2 big trucks and about 4 men. They brought the wet leveling product up via a long hose through a window into our second floor condo. We left the condo at this point. They worked for about 8 hours we believe. We returned two days later. We walked around the condo and the floor looked beautiful. BUT, the floor WAS NOT level!! They overfilled where the floor was high and underfilled where the floor sank. I wanted to cry. After lots of calls, the owner's son came over and said the floor looked beautiful (it did) and said that my husband was being too nit-picky. The man literally said "We NEVER said it would be 'level.' We said it would be flat." (The business name is Acousti-"LEVEL.") We knew we would not be able to get laminate flooring with the dips and rises the floor had. (We used a level and found out the floor level varied everywhere.) My husband just kept telling the man "I want a LEVEL floor." The owner's son finally said he couldn't get anyone to come back and relevel it in the week my husband gave him to get it fixed. The general contractor that had bid $750. to do the floor (and we declined) offered to ask his tile man if he would relevel it. So my husband told the owner's son that we knew someone who could relevel it. The tile man bid $1750. and after a lot of haggling the owner's son gave us the go ahead to pay the tile man out of the money we were to pay him. The tile guy hand-leveled it and it is pretty level now. We believe something went wrong the first time. Either the crew that was sent was inexperienced or the mix they used was defective or not mixed right. A self-leveling material does not flow uphill. The tile man had to grind down as much concrete as he had to raise. My husband thinks possibly the first crew manually moved the leveling material around which raised some areas and left some sunken. I am glad that the entire floor is now covered with the leveling material. (Some type of gypcrete???) I am sad that after paying almost $7000. the floor was not done right the first time. It should have worked but something went wrong. If my husband had not been assertive and not continued to reply (like a broken record) "I want level floors" I don't think ANYTHING would have been done. Our floors were FINALLY leveled the second time about a week ago. We decided to not get laminate floors. We are getting Luxury Vinyl Planks instead. The flooring we originally wanted, both our first and second choices, were no longer in stock thanks to all of the delays. The flooring we did get is beautiful but doesn't match our other wood furniture. We couldn't find a good match. (Lots of shortages of everything due to the pandemic.) The smartest thing we did was to NOT pay the company ANYTHING until after they were done. I think that's why they allowed someone else to relevel the floor and be paid out of the money we owed the leveling company. Once the floors were level we paid both places. We did get three bids for the work which were pretty similar in cost but we went with the first company that could do the work. I think with hindsight I would ask for references FROM INDIVIDUAL CONDO OWNERS (not NEW builds) and then CALL THEM. You should definitely get a company's CCB # and look up their record with your states Construction Contractor's Board. Also you should look up the company with the Better Business Bureau. We had looked up the company we hired and they had a spotless CCB and BBB record so a spotless record doesn't mean they have always done a good job. We found three floor leveling companies and got three bids by googling "floor leveling companies in (your city or state.)" It was difficult to find companies and difficult to find people who had time to do the job. Two other companies we found (but did not use) were Ultra Quiet Floors, and Sound Floors. Four months later: Was it worth it? It would have been almost perfect if the first company had done a good job. Once the tile man leveled the floors, yes, it was worth it. The floors seem to be level and we are no longer (literally) tripping over them because of how uneven they are. They were AWEFUL. We are crossing our fingers that we can have our LVP flooring installed. The same GC that hired the tile man is also hiring the crew to lay the floor and if it isn't totally level we expect him to level it again if needed so we can have the flooring we want, and have already purchased. We are adding an underlayment which the GC recommended to help stop noise transmitting to our downstairs neighbor's condo. The floor still vibrates but it is much better and we do not have flooring or furniture in yet. We are also adding room size rugs to the bedroom and living room which we believe will help with the shaking and also help to stop noise transmission to our neighbor's condo. I have read that the weight of furniture helps stop the vibration. I hope that is true. Now that we have been walking on the floors for about 4 months I am not quite so unnerved by the shaking. I've also been assured by several people including SJ McCarthy (above), a structural engineer, and a former boss of my husband's who is a structural engineer with many condo's under his belt, that the "vibrations" we are feeling are normal for condo's built in the 70's. I didn't mean for this to be so long but man could I have used some reassurance when we ran into this problem last June. If I can answer any questions you might have, please ask. I am glad to help. If I were to do it again, I would get the floor leveled for sure but I WOULD NOT DO IT if I couldn't get references. And I think I would watch the work being done as best I could and definitely NOT pay them until the job was done. I think that is the only reason the company paid for the second leveling out of the money we were going to pay them with. They wanted to be paid. I guess I would end by saying that I have heard many times, if you don't do anything else, wall to wall carpeting can eliminate a lot of the shaking. I wish you the very best. Margie