Similar idea as prefab homes.

Tsilanko, I would always recommend professional installation where needed. But what I am doing here is suggesting that WHEN you are planning to build or renovate, to consider how your plans will affect you in 20 or 30 years time. Split levels are very hep when you are young. A kitchen 3 steps down at 30 is rarely a problem, but might be a hazard at 60, or, as Marjie1059 suggested, if you break a leg. ... All my parents' homes were terrible for old people. They were forced to move to a bungalow in extreme old sge because the location and design of their home was more suitable for an active young couple with a large family than for an elderly couple with stroke disabilities. I would not want to move again, so my present home has features built in that make ageing in place simpler. Mostly small changes, like grab rails, and lever handles on doors and faucets. A major disability suddenly suffered requires major changes if permanent. I did look at this because it came up in the discussion, but if you look at the heading, Planning for Disability, it means just that. Plan ahead so you don't have to make expensive changes later on. But thank you for your advice, yes, major changes are not in the DIY domain.

Mohammad. I understand your program. You may be lost in the details at the moment. Please do follow and trust the advice given here by all these people. You are about to embark on a reasonably expensive journey. Get professional help with someone who you can sit down at a table and brainstorm with them your ideas and intentions. There are Architects and there are professional building designers who are members of the American Institute of Building Design (AIBD) who are well versed in projects such as yours. I personally love a design challenge. After 38 years designing homes and special use buildings I enjoy this type of challenge the most. I am in Ohio and may not be close to where you are but I am sure with a little investigation you will find the best design professional for you.

It’s great you're focusing on recycling! If the dado tiles are in good condition and neutral, you can leave them, but check grout and overall security. When replacing bathroom floor tiles, ensure the waterproofing layer remains intact, as redoing it can prevent water damage. For plywood, if the quality is good, you can reuse it, but ensure a skilled carpenter finishes it properly. The kitchen countertop can be reused if carefully removed and in good shape. Just make sure all structural and waterproofing aspects are intact.