1. Ossa Accentium
2. Pantherfang Chapel
3. Kushalit Sanctuary
4. Moon-Sugar Meadow
5. Lakemire Xanmeer Manor
6. Shalidor's Shrouded Realm
7. Varlaisvea
8. Amaya Lake Lodge
If you own any of those homes, you can find out either by using the Magic Carpet addon to climb up, or buying the cheap Limestone Steps from the Alinor Home Goods furnisher and building a temporary staircase up, until you hit the invisible ceiling.
I like building towers in my outdoor homes, and I especially like it if I can build higher than anything else in or around the home, or at least as high.
For anyone interested, here are the height limits I've tested out in the homes I do own.
Red Eagle Aerie: The invisible ceiling is exactly the root height of the tallest tower (the one behind you from existing the West staircase). Magnificent view of Markarth though, but you already had that from the balcony.
Grand Psijic Villa: Disappointingly, you can't get very high at all.
Serenity Falls Estate: Same.
Exorcised Coven Cottage: Surprisingly, you can get very high here, far above the cottage and walls, albeit it's a narrow cylinder bound the fence. View is decent, though partially fog-shrouded.
Emissary's Enclave: The invisible ceiling is about the height of the tiptop of the two prongs at the top of the tower. You can stand on the roof between those prongs. Decent view of the docks on one side and Necrom on the other, though you're not taller than the mountains and can't see over those.
Hunding's Palatial Hall: The invisible ceiling is slightly higher than the tiptop of the tower. You can build the tallest structure around, and have a great view of Stros M'Kai and the ocean.
Kelesan'ruhn: You can't build particularly high.
Doomchar Plateau: You can build very high, much higher than the one structure, more or less on par with all the mountains around you in the distance. Magnificent view, so long as you like lava.
Hall of the Lunar Champion: For Halls of the Colossus, you can build up to around the height of the pillars, if memory serves. For Lion's Cradle you can build surprisingly far out from the railing and fairly high up, with great views of the forested mountains below, but nowhere near as high as the mountain behind the portal there.
Agony's Ascent: You can build amazingly high, which makes sense given the height of the central tower. You can build tall enough to stand on the rooftop, though not much taller than that. Sadly, the view is terrible, nothing but fog. Please fix this, ZOS!
Antiquarian's Alpine Gallery: You can build pretty high, but not higher than the mountains. Decent view of Skyrim woodland.
Orbservatory Prior: On the front platform, you can't build too high, and if you try to go very far below the platform level, you'll hit the "auto-die" plane that would trigger if you jumped XD In the observatory sections, you can't build out through the gaps in the orrery.
Any information about the height limit (and the quality of the views there) in other houses is welcome as well, though I personally am mostly curious about the houses I listed up top. Thanks!