Elevated plot - Filling / Leveling / Foundation

Hello everyone,

we are about to buy a sloping plot with an area of approx. 920m² and start construction during the year. Since the whole thing will be a bit more difficult due to the slope, I wanted to get your opinion on our current idea:

1) The natural ground surface rises from street level by approx. 4.5m in height over a length of approx. 33m. To achieve a larger flat area, we have planned to have the area of the building volume and approx. 2m around it raised by approx. 0.8m. Our contractor recommended RCT (apparently recycled concrete) for this, which will be compacted in layers, followed by a plate load test. Underneath that a geotextile. A soil report is available. According to this, foundations can be made with normal strip foundations or as a slab foundation. Is this still the case if filling is done? Can the foundation then be made on the RCT? Otherwise, I have heard about the possibility of creating a so-called blind plinth. What exactly does that mean? What would be the advantage? Unfortunately, I could not find anything clear about this on Google. The development plan includes a textual specification that the plinth height may not exceed 0.8m.

2) The rest of the slope is also to be divided into 2 more or less equal-sized (flat) terraces. What should be considered here? How would you stabilize the slope?

3) On the northern boundary, a carport is to be built as an attached carport (approx. 3-3.5m wide) over a length of 9m, to utilize the possible boundary building of 9m as optimally as possible. The filling is to be secured towards the neighbor side with L-walls (1m). In my opinion, due to the regulations on boundary construction, we must also ensure that the natural ground surface is not exceeded by more than 3m in height (0.8m for filling + max. 2.2m for the carport). Is that correct?

I have created 2 sketches for the planned terrain modeling (side view + top view). The top view comes from the development plan, on which the current contour lines are also drawn. These are the parcels 451+452 (which will be merged into one parcel before construction starts).

that the natural ground surface is not exceeded in height by more than 3m (0.8m for fill + max. 2.2m for the carport). Is that correct?

Yes, or more precisely, at the boundary, the average wall height (i.e., top edge of the parapet) of the carport must not exceed 3.0m. But why do you want to add fill for the carport and what will you do with the good meter of height difference between the front and rear edge of the carport?

Raising the carport by 0.8m won't work. How do you want to cover the height difference with the car? Even over 10m, that's still an 8% incline...

Hmm slope. It's quite similar for us, that's why we're building with split level.

With 4.5m over 33m length, it's about 1.5m over 10m. So roughly half a floor difference over the length of a house.

I really don't want to impose split level on anyone, but in cases like this it really suggests itself. Especially when the alternative would be a small violation of the terrain's natural slope...

1) The natural ground surface rises from street level over a length of approx. 33m by about 4.5m in height. To achieve a larger flat area, we have planned to have the area of the building structure and about 2m around it raised by about 0.8m. [...] In the development plan, there is a textual provision that the base height may not exceed 0.8m. [...]In my opinion, we would then also have to observe the regulations for boundary development, that the natural ground surface is not exceeded in height by more than 3m (i.e. 0.8m for the fill + max. 2.2m for the carport). Is that correct?

How the base height is supposed to work together with the slope, I don’t see coming together quite smoothly yet. The problem with many such heights is that a large portion of them are measured "absolutely," i.e., unfavorable reference heights cannot then be remedied by altering the terrain. To be able to help you further, I see — here as in your other thread about the number of stories — the time has come to step back from the small deviations and to analyze the development plan "with horse and rider." Otherwise, you will only be able to collect countless speculations.

However, you should really think carefully about split-level. We currently live in a split-level and it is definitely a major reason for us wanting to build ourselves. Once and never again. Every damn thing involves stairs, which is incredibly annoying in everyday life.

You can't just put a standard house on your plot. Here you need professional help. The costs for modeling the plot are around 30-40k euros for you. Options are, as mentioned, split level, or a basement with an integrated garage, etc. But I rather assume it should be cheap for you. As an example, retaining L-shaped blocks for 2.5 meters height costs about 600 euros each for a 20-meter plot × 20 plus excavator + concrete, etc.