ᐅ Is Deep Foundation Required for a Terrace or Driveway?

Hello fellow home builders,

Our house construction is planned to start this summer.
A brief overview:
- Approximately 140 m² (1507 sq ft) single-family house for 4 people
- Plot of about 1000 m² (0.25 acres) in northern Lower Saxony
- Soil has low bearing capacity due to a lot of peat. Deep foundation according to soil survey required, with piles up to around 18 m (59 feet) deep
- Very high groundwater level
- Terrace of about 35 m² (377 sq ft) directly adjacent to the house, which might be upgraded with a conservatory in a few years

Locals have told us that almost everything here requires deep foundations, practically even for the smallest garden sheds. Structures without deep foundations tend to settle, meaning driveways or terraces would need frequent repairs.
An alternative (used in road construction) is long-term “preloading,” for example with sand mounds several meters high, but this is expensive and unfortunately we don’t have the time for that.

When consulting professionals, we have received conflicting advice.
One says it’s sufficient to excavate and ensure a proper sand base, while others say the terrace and driveway need deep foundations and footings if we want to avoid ongoing repairs. Especially a conservatory wouldn’t be possible without deep foundations, etc.

Do you have any experience with this topic?
We appreciate any advice!

You should take the statements from local people and neighbors seriously.
Why do you want to experience negative situations yourself first?
Highways are built based on expert advice, only to sink shortly afterward and become completely unusable, as with the A20.

18-meter (59-foot) foundation on peat?
That probably means old bog = Deep foundations are absolutely necessary, otherwise it will settle.