In my experience the set of wall/floor coverings you are talking about came with one of the patches between 1.17 and 1.22. I can't say certainly because I updated straight from 1.15 to 1.22 when EP4 came out.
I'm not sure if they came in this late, but they indeed came from a patch. I seem to recall that I was using them as early as WA. But they weren't there one day, and then suddenly they were.
I don't like to just throw houses together in edit town. I have much more fun making my Sims pay for building and furnishing their houses themselves. That junk television is a real treasure when your Sims have refilling their fun bars by reading the newspaper. So my tips apply mostly to that kind of situation.
First and most importantly: Rebuilding is
unbelievably expensive! Well, you've likely experienced it at one point so you probably believe it lol. My point, however, is that the most frugal way to build a house is to build it the way you want it the first time. Map out the floor plan for your house with the free floor tiles. But as they say: time is money, so this tip applies to building a house in edit town as well. Rebuilding can be a time consuming and occasionally frustrating endeavor, and knowing what you want to do before you lay your first bit of foundation or place your first wall saves loads of time.
Also, if you place walls and don't like what you end up with, always click "Undo," even if it means eliminating work you've done since. Walls depreciate in value the moment they are placed, so if you use the sledgehammer tool to remove them, you will not get back what you paid for them. It's a loss of
$18 per section, so if you're redoing a bunch of walls, this loss will be horrendous. This, of course, doesn't apply if you've gone back to live mode since you placed the walls...at that point there's nothing to do but grin and bear it. So always look at what you've done before you return to live mode to make sure it's what you want. This loss does not apply to building houses in edit town mode.