ᐅ Building a House on a Slope – When Is It Better to Avoid It?

We currently have a nicely located sloped plot in view for building a house. However, the consistent slope of about 23% (5.5 m (18 ft) over 23 m (75 ft) length, evenly declining) is somewhat concerning. It is a north-facing slope; access from the street at the upper side of the plot is no problem.

The north-facing slope bothers me less because I prefer cooler conditions and there is no risk of additional shading from neighboring houses. The plot price is attractive, so additional costs due to the slope can be managed more easily.

We plan to build only a ground floor and a basement into the slope. Access to the ground floor would be relatively barrier-free.

1. How should this slope be evaluated? Does a 23% gradient cause significant additional costs compared to flat land?

2. At what slope gradient should one avoid building on a hillside?

3. Is a soil survey recommended, considering the soil is sandstone with stones to be expected?

4. What are the approximate costs per cubic meter (yard) of earth if soil material needs to be transported for terrain modeling?

5. Are such sloped plots manageable for...

80,000 additional costs

+ 25,000 euros for the exterior wall on the hillside side
+ 5,000 euros additional cost for reinforcement in the foundation slab and thicker solid wood ceiling

+ Earthworks including retaining walls in the garden

Make an appointment with one or preferably two potential construction companies and ask for quotes for the earthworks. There are regional differences.

I estimate that around 80,000 euros will be realistic. It also makes a difference how you want the outdoor area. Terraces and retaining walls can be built with L-shaped blocks, requiring little additional excavation,
or from the basement level upwards, everything flat with a lot of excavation, and a poured retaining wall with extensive reinforcement.

The structural engineer may require a geotechnical engineer. Ours insisted on it.

23% slope is quite flat. ;-)
At the steepest point, we have 20% more.

On the other hand, how much extra are you willing to pay for the slope, possibly with a better view? We have a 16% gradient over 22m (72 feet), and that is already very expensive to compensate for.

A maximum additional cost of €40,000 due to the sloped terrain would be acceptable. It is appealing that the width of the plots, and therefore the plot area, can still be determined, as a larger sloped area is available for building sites (all equally inclined).

Thierse schrieb:
(5.5 m (18 ft) over 23 m (75 ft) length, sloping evenly

And how does it look across the width?
In any case, that is a full story height within the building envelope. Additionally, there will be some filling if the terrace is not intended to slope as well. Which direction does the valley view face: the lake district or the school center / hospital / courthouse?

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