Cusom windows may help.
To simulate the approximate scale, the resultant house may have to be larger in size to the sims.
After all, the morph is interesting...
What I see how it can be built:
Surely, compressed/warped walls along with the cheat "boolprop constrainfloorelevation false/true". It may take switching between the cheat's state to accomplish it unless it's well planned.
Let's assume the giant windowed outgrown area is a floor itself, probably it can take 2-4 levels to do it.
Say, 2 4-click-high compressed/dummy walls are to make up the top and the bottom parts of the top left grown area. The window can be just a normal 1 floor-high wall with french windows.
What I mean a floor here is room a sims needs to access (normally at least 16 clicks interms of the terrain tool.) A floor can contain as many levels as your PC can afford while certainly one level is the minimum.
For the middle lower window, it can be a one floor high wall as the lowest base wall on the upper floor. The wall piece in-between the middle windows can be the remaining gap from the base wall (the part unoccupied by the lower window).
The upper midl window may be done using Numenor's wall-windows 's glass fence or other shorter glass fences along with a level of compressed walls. The middle upper window can be a challenge to do even for an experienced window-maker, so a fenced-based window should be easier to simulate it and has wider usages...
As for the right hand side, there'll be about 3-4 levels of wall to accomplish the front. The ground floor is gonna have a shortened wall probably (if shortened < 16 click-high, try not to tile those areas <16 clicks for sims accessment unless the ground has been relatively lowered as well to keep 16-click-high.)
The right lower window can be done by a fence-based custom window or just a glass fence.
The wall piece in-between the right windows can be a level of compressed wall of 4-click-high.
The right upper window can be a normal wall while the warped wall pieces will be on the outgrown side walls. So, it's more like the upper level is deformed down to make up the outgrown right upper window.
1. may use those without pattern or at least those without horizontal linings:; non-patterned or straightly-klined ones are fine without showing any warping normally.
2. Yet, you make custom wallpaper with patterns that can cancel out the warping appearance. Surely a little bit more work on the wallpaper-texture handling. But, this works.
There can be other ways to achive different parts of the building, the one suggest here is unnecessarily the only one or the best one. Keep this in mind.
I can't see the other parts of the buildings or its interiors, so I assume the above suggestion should work at least.
The followings are 2 lists of tutorials you may wanna learn from to make split levels, split stairs and warped walls.
Remember, no need to read all of them, probably just some of them dependent on what you think'll need as you started to have read 1 or 2 in a particular listing. Try to comine those ideas together, then you may see what I mean above if not having got it yet.
Split level or split stair tutorial listing:
Why split levels and split stairs?
The biggest relationship between them is that for a given split level, it normally takes split stairs to connect them in order for sims to access through them. Also, a split stair landing is actually yet another split level. So, whether one is building one of them at a time, the approach to do them is basically the same.
(Non-NL or above EP) (compressed/warped wall-based) Hlalf-walls and Warped walls:
Why compressed/warped half-walls?
The default wall (Wall 1) can be easily compressed or extended into various shape by mean of the cheat boolprop constraintfloorelevation (false\true) along with the terrain tools. In order to craft the wall shape you want, learning to know how TS2 walls can be shaped is the first step. The half-wall approach Mikeinside showed prior to NL release is a way to learn a basic way to do so.
Windows are obviously the big problem with this. Elevation wise, the two higher areas would be made up of the 'normal' wall on the 2nd floor and a 4 click dummy level above. (See Mike Inside for more on dummy levels.)
You can use move_objects on to put windows in places where they wouldn't ordinarily go -- but they don't always cut out the window hole in the wall, plus there is no way to change a windows height in the game. Size and height have to be done at the mesh level.