ᐅ Semi-detached house without immediate neighbors: Wall insulation

We are planning to build a semi-detached house (duplex) without immediate neighbors. We have already obtained the building permit / planning permission and have started construction. Since we are uncertain when the other half of the plot will be purchased and built on, we need to consider the insulation of the shared wall.

Our main question: what are the expected costs for this, and how should we proceed?

Usually, exterior walls are much better insulated than the partition walls. The construction company assumed that the other half would be built soon, which has not happened. Making changes to the building structure is not possible.

On the other hand, the building specifications state that the house must meet the KFW-55 standard. Would it not contradict this standard to leave the partition wall without insulation? The construction company told us that we are responsible for the insulation of the partition wall ourselves.

What can we do in this situation, and what is the best way to handle it?

If we want to improve the insulation of the partition wall between the semi-detached houses, the question arises whether we would already be on the neighbor’s property while doing so. Is there some distance between the partition walls that we can use for insulation, or do the walls directly border the neighbor’s property?

I look forward to your help.

Bauherrin_987 schrieb:

We are planning to build a semi-detached house (duplex) without direct neighbors. We have already obtained the building permit / planning permission and have started construction. Since we are unsure when the other half of the property will be purchased and developed, we need to consider the insulation of the shared wall. [...]
If we want to improve the insulation and soundproofing of the dividing wall between the two semi-detached units, the question arises whether we would already be on the neighbor’s property. Is there a certain gap between the dividing walls that we can use for insulation, or do the walls directly adjoin the neighbor’s plot?

Semi-detached houses are typically built right on the common boundary line. As a standard practice, a setback of about 2cm (1 inch) from the boundary is made on each side to create a 4cm (1.6 inch) gap between the two units.
1. This means you likely have not only a temporary insulation issue but also a weatherproofing problem with that wall.
2. It is advisable to plaster the insulation immediately.
3. The insulation will unavoidably extend onto the neighbor’s property.
4. This temporary wall surface will be “lost,” meaning it will have to be removed at your expense when the neighbor builds their unit.
At least the rights of entry for construction and removal work—the so-called “right of hammering” or “right of ladder” (search these terms in the forum)—will assist you. If you are building without a basement, be prepared for challenges once the neighbor begins construction (see also the related discussion in the Goalkeeper thread).

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