Tent (5,000 Nook Miles) -
When you first move in you're limited to a tent, and are charged 5,000 Nook Miles. These are points you earn by doing different things in your island, and are accumulated pretty quickly. This upgrade is not an issue at all to pay off. As for it's size? It's basically the same as the original small default house from past games.
House ( 93,000 Bells)-
This is the first home upgrade, and is the same size as the past. It's slightly bigger than the tent, with an extra row of tiles being added around the outside. (Keep in mind the door location does not move, only the East, North, and West walls will be expanded.) This is also the first house upgrade that actually requires Bells to pay off. Thankfully this can be done a little at a time, but you should be able to pay it off in no time just by selling fish and bugs.
House Upgrade ( 193,000 Bells)-
This is the second upgrade, but the first upgrade to your house. Once again it adds extra tiles around the outside of your house, and is the final upgrade for the main room of your home. This is the original max size that's been used since the days of the original Animal Crossing. As you can see the tiles are roughly 8x8. (I say roughly because we can now move furniture at halves, and push things closer together.)
Back Room (348,000 Bells) -
The next upgrade is to your back room. This does not change the look of your house, but gives you an additional room to place furniture in. The size of this room is the same as the "normal" house upgrade, and cannot be expanded anymore than this. This size is 6x6.
West Room (548,000 Bells) -
Once you have a Back Room, the next upgrade is to add a room to the West. Once again this is the same size as the Back Room (6x6), but it does make your house look wider in general. The shrubs that used to be outside your home will now be replaced with a wall, but thankfully this does not take up anymore space outside. It is purely cosmetic.
East Room (758,000 Bells) -
Same as the West Room, except to the East (6x6). This completes the bottom story look for your house.
Upstairs (1,248,000 Bells) -
The next big upgrade to your house is the upstairs. Unlike past games however, this time things are quite a bit different. Previously the upstairs was the same size as the North/West/East rooms, but now it is much wider. The actual size is 6x10. Yeah, this one is also crazy expensive.
Basement (2,498,000 Bells) -
The Basement has also received the Upstairs treatment. Rather than being similar to your main room, it is now an extra wide area of the same size as the upstairs (6x10). This is the "Final" home upgrade, but things don't actually stop there. On another note, at this point you'll have a maximum storage of 1,600.
External Customization (Free After Pay Off) -
Once you have upgraded most of your house, you gain the option to customize the outside of your house. This means you can change your roof, your door, and even the siding and mailbox. This does cost of course, but once you pay off your Basement that fee goes away. A fully paid off house can use this service anytime, and it comes completely free! Of course that Basement fee is pretty expensive, so it evens out in the end...
And that's it for the housing upgrades! Again it's pretty similar to past games, but two of the rooms have been altered, and the external customization has been changed. Pretty nice additions overall, but it also means you won't be able to recreate your old houses anymore. But isn't the point of starting a new Animal Crossing to change things up anyway?
