ᐅ The ground beneath the garage needs to be stabilized because the neighboring property is at a lower elevation.

Hello,
my husband and I are building a detached house with a garage and have encountered a small problem. Our plot is situated significantly higher than our neighbor’s. We would like to level our very sloped terrain to a uniform height. The finished floor level, the garage, and the surrounding garden area should all be set to the same height to allow step-free access everywhere. Only at the main entrance to the house will there be a step.

The issue is that our neighbor will not add fill, so there is a slope of about 1 meter (3.3 feet) down to their property. This is not a problem for us; it was already approved with signatures as part of our building permit/planning permission, and we will secure our property boundary toward the neighbor with L-shaped retaining walls.

Our problem is the garage. It is located exactly between our house and the property boundary to the neighbor; in fact, it will be built right on the boundary line. The question is, how can the garage foundation, which extends right up to the boundary, be supported? Should the retaining walls be extended and the foundation poured against them? But then, is it possible to get the exact same height? What are the options here?

You will probably need to construct quite deep strip foundations, I would assume.

How are you planning to build? With an architect or a general contractor? They would be my first points of contact.

With the architect, unfortunately, there is not much help at all..

Depending on the height difference, a proper concrete foundation must be poured; if the architect can't coordinate this properly with the structural engineer and the builder, then they are not on the right track.

Christina W. schrieb:

With the architect, but unfortunately, they are not much help..

Then I assume you mean a draftsman working for the general contractor. Think carefully again whether the costly battle over the highest possible fill is really necessary. If the neighbor’s property can be a whole meter lower, it seems the street or driveway does not actually require such a large elevation difference.

Also compare this case—you’ll get a different perspective here: https://www.hausbau-forum.de/threads/wie-weit-hoch-boeschen-zweck-frostsicher.36289/

Christina W. schrieb:

and we will secure our plot towards the neighbor with L-shaped retaining walls

Maybe @Zaba12 can provide a reference showing what it looks like when neighbors start an L-wall battle, just to discourage that (?)

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Christina W. schrieb:

Our problem is the garage. It is located exactly between our house and the property boundary, so it will be built on the boundary line.

How did you address the building regulation issue concerning the 3m (10 feet) height limit for boundary constructions? Since the planner is aware of the height difference, they must already have solutions for all resulting issues.