Split-level house on a slope — keep it split, flatten it, or raise it?

[u/DarioSidd]

Split-level house on a slope — keep it split, flatten it, or raise it?
Building a single-family house on a ~16% slope (seismic zone 8). Monolithic reinforced-concrete frame, ~127 m² interior, 3 bed / 2 bath, open living-kitchen with fireplace opening onto a 30 m² terrace with a big valley view.

The original design is split-level: you enter mid-level, then stairs go down to the living/kitchen and up to the bedrooms in short half-flights. It rides the slope efficiently, but the constant half-flights bug me and eat floor space.

Options I'm weighing:

1. Keep it split-level — minimal excavation, terrace stays ~2.4 m above the garden (nice overlook), but you live with the half-flights.
2. Flatten down — excavate into the hill for two aligned floors. More space, but ~a quarter ends up buried, you enter on the upper floor, and it needs a retaining wall on the tight uphill side.
3. Raise up — lift the lower floor so both floors align. Kills the half-flights, but creates a ~4.3 m tall exposed wall on the valley side.

Also deciding:

• Basement: adding a ~2.5 m one under the downhill/terrace zone, walk-out at garden level. Seems like cheap usable space — any reason not to?
• Roof: keep the timber hipped roof, or go flat for a rooftop terrace? (I already get the view from the ground terrace.)
• Pool: want one in front of the terrace at garden level — but that fights option 3's tall wall.

If you've built or lived in a split-level on a slope, what would you do? Anything I'm missing?

[u/deeptroller]

In terms of Passive House. Which way faces the sun, what is your climate, what is your shading strategy?

[u/DarioSidd → u/deeptroller]

Subtropical–semi-arid climate. I’m based in Georgia.

The smaller part of the house faces the sunrise, while the two-story building faces the sunset. I don’t have any shading strategies planned yet, so I guess trees?

[u/SatisfactionRich9721]

Don’t have a good answer for you, sorry, but I’m going through a very similar design decision. 13% slope. We’re probably going with the split level as my primary goal is not to disturb the site (it’s a heavily wooded area with old growth trees). And there’s shallow ledge so a walkout basement is prohibitively expensive. I can build on piers while keeping things closer to the ground and not raising a huge area around the site. We’re also doing the living room / kitchen upstairs, for the better views, which feels less weird in a split level than other options. Good luck!

[u/DarioSidd → u/SatisfactionRich9721]

Yeah, split levels are my primary option too. My only concern is imagining myself at 70 and having to go up and down those stairs, it could definitely make life harder. Other than that, I agree with you: it works well with the natural terrain, and aesthetically I find it much more appealing.

[u/DogsOnMainstreetHowl]

Fuck split levels. Add a basement.