wavy yard; a risk when buying a house?

Hello, I came across this forum while googling and hope to get some help here. I want to buy a house that is feasible for me in terms of size and price. It is a 20-year-old house that was built in a relatively simple construction style, basically "built for tenants," I would say. The house seems quite solid, but a partition wall was installed in the living room with a slightly wider wooden door that "works," as the previous tenants say. Is that normal or a cause for concern?

What worries me more, however, is the paved courtyard. The stones appear to be pushed up from below. Since the house is in family ownership, I know that the same problem occurred about 6 years ago and the courtyard was then repaved.

Now my question is whether this work was simply not done properly, or if there are general concerns about the ground when buying the house? Could the foundation slab crack?

There are also other houses there that are mostly older, but I cannot see any defects externally (cracks in the walls, etc.)

By the way, the house does not have a basement.

It would be great if someone could help me.

Thoughts from the amateur paver ....

Hello Andrea,

years ago I paved a few paths and dealt a bit with the subject. I still remember very well the term "auskoffern". That means that the existing insufficiently load-bearing layer is excavated to a certain depth. With professionals, I could only observe this when a road was newly built. For existing roads and paths, it was apparently always assumed that the subsoil was still okay. Then only the bedding gravel and then the paving were applied.

However, many smaller construction companies or illegal workers also pave like this when the subsoil is not okay: for example, the gravel is dumped on humus, the stones are laid, everything is compacted firmly and then disappeared without a trace. When effects like those you described occur later, those affected usually do not even have an invoice, let alone a warranty.

Paving must, in my opinion, be laid frost-free and on a firm, load-bearing subgrade. For this, in my opinion, a mineral layer at least 20 cm thick should be laid under the bedding (mineral mixtures with grain size 0/32 to 0/56). If the subsoil is particularly critical, a frost-free foundation depth should be observed as with foundations (80 to 100 cm depending on the climate zone in Germany). This means in the extreme case: excavate to this depth and rebuild in layers, compacted frost-proof. No wonder everyone wants to avoid that. The effect of warping could, in my opinion, come from the fact that no frost-free foundation was made. If it freezes under the paving, water expands due to its anomaly (ice crystal formation) and increases in volume. The upper layer is pushed up.

I would not necessarily connect paving problems with an alleged poor foundation of the house, unless the house and yard were built by the same company :-)

Regards