Structural assessment of the slots for electrical and air conditioning systems

Does the general contractor want it only at the very last hammer strike?

As far as I understood, no interim acceptance is planned. Only the final acceptance at the end.

That’s why there are regular visits from the expert to document the intermediate steps.

Yes, we only agreed on interim inspection points. One of them would be after the rough installation (before plastering and screed).

ours looked pretty much the same as yours....

Yes, then let's hope they are good enough.

No, I meant your approval for the construction contract fulfillment achieved so far -

There is none. It is the payment based on construction progress, which legally would not even be a tacit acceptance.

Should a structural engineer be consulted here, or is the confirmation from the electrician enough?

The static calculation was already done in advance. Is there an implementation plan? The recess should be shown there.
Of course, it is better if the cable duct is placed in front of the wall, but then, wherever this is now (kitchen?), there would be a visible boxing. Some people consider that a defect. In some areas, it is indeed one.

Request from the air conditioning technician:

It’s nice and sweet that he asks. Vertical slots usually should not be a problem.

Basically, the whole problem is once again indicative: construction with a general contractor no special additional services. There could be problems and trouble, and later he gives no guarantee on anything.

The static structural calculation was already done in advance. Is there an execution plan?

Yes, the static calculation was already done in advance, but I do not have the structural plans. There is no execution plan for these details.

Of course, it is better to place the cable duct in front of the wall, but then, wherever that is now (kitchen?), there would be a visible boxed-in section.

That may be better from a structural point of view, but not from an aesthetic point of view. We have the internal unit both in the living room and in every bedroom. I am doing the rough installation now to avoid these cable ducts.

Basically, the whole problem is also indicative: Building with a general contractor means no special additional services. There could be problems and trouble, and later there is no warranty from him on anything.

I do not fully understand the general recommendation. I thought it would be better to separate the work as much as possible so that there is clear responsibility for the general contractor and for the other hired companies. In this way, possible problems can be attributed to the correct party and there is less confusion or liability issues, right?

I thought it would be better to separate the work as much as possible so that there is clear responsibility for the general contractor and for the other contracted companies.

This way, possible problems can be assigned to the correct party

I don't see it that way: if there is a structural problem related to the condition of the walls, the general contractor can blame the cause on the HVAC guys. Or vice versa. That is warranty trouble – it will also be written in small print in the terms and conditions.

I generally have no concerns either. However, I wouldn't necessarily have placed the installation route for the risers in the exterior wall (insulation). For example, this can already be taken into account during the structural calculation. I told my shell builder and structural engineer during the planning where I wanted to place my distribution boards. The shell builder then immediately left an opening in the wall and ceiling for me. After completing the electrical installation and before plastering, I closed it with lightweight mortar. I think it will look the same for you.

Hello again to everyone,

I wanted to give you an update on this topic. We have now received the expert report, and it raises concerns about two aspects of our electrical installation:

1️⃣ The large cable duct in the exterior wall

2️⃣ Empty conduits on the raw ceiling


I would like to hear your opinions and suggestions regarding this:
✅ Are there actually any problems with fire protection in such an electrical installation?
✅ Which measures would be sensible for the empty conduits to avoid problems with the screed?


Background: The empty conduits run to the large cable duct through a narrow corridor on the first floor and from there to the technical room in the basement. An alternative routing was apparently difficult to realize.


I look forward to your expertise and your suggestions!


Many thanks and best regards!


2. Findings
2.1 Electrical and Smarthome installation

[*]Increased load on power cables compared to standard buildings detected. This is due to the additional wiring for the smarthome system, resulting in more cables distributed throughout the building than usual. Especially in the area of the main cables, numerous cables are bundled, which can cause both space issues and thermal stress. A detailed review of the cable routes is required here to ensure that no overheating or inadequate insulation occurs.
[*]Cable duct with a width of approx. 48 cm and a depth of approx. 18 cm present in the exterior wall. (see photos 1.1 and 1.2)

[*]This design could cause damage to the wall construction as well as to the thermal insulation
[*]Recommendation: Check an alternative cable routing within the interior walls and properly close the open duct with suitable material
[*]Fire protection: All cable ducts must be closed with approved materials according to the applicable fire protection regulations in order to minimize fire risks.
[*]Screed preparation: Due to the multitude of laid cables, air gaps may occur in the screed, which can cause cracks or settlements in the floor. Special care is required here. (see photo 2.1)

2.4 First floor

[*]A cable duct with similar dimensions was also found in the exterior wall on the first floor. It runs vertically along the exterior wall and affects both the structural integrity and the thermal insulation performance of the building. Due to the depth and width of the duct, there is a risk of thermal bridges, which can lead to energy losses and possible moisture damage in the long term. Furthermore, the structural integrity of the load-bearing exterior wall could be impaired due to the weakened structure. It is urgently necessary to check whether an alternative routing of the cables within the interior walls is possible to avoid these negative effects. If this is not possible, suitable measures for proper closure of the duct with structurally appropriate material and a complete restoration of the insulation layer are required. (see photos 5.1 and 5.2)

[*]Recommendation: The cable routing should be optimized to enable better guidance of the installations. Air gaps in the screed are to be avoided. (see photo 6.1)