ᐅ EIFS / exterior wall / insulation / energy experts’ experience reports

€uro schrieb:
Pay attention to the vapor permeability of the external thermal insulation composite system (ETICS). The higher the proportion of the load-bearing Poroton brick in the total thermal resistance, the more vapor-permeable the insulation must be. This can sometimes limit the choice of suitable building materials.

Best regards.

.. so basically, is it safe to say that, for the reasons mentioned above, choosing a thicker brick wall is rarely a mistake?

How can I calculate the cost-benefit ratio if I switch from the 24 cm (9.5 inches) brick + 16 cm (6.3 inches) ETICS recommended by my architect to, for example, a 30 cm (12 inches) brick + 10 cm (3.9 inches) ETICS?

Thanks and best regards

Hello,

Stefanoi schrieb:
but what exactly are the advantages and disadvantages of a thicker monolithic wall?

Here, the initial question referred to purely monolithic construction or masonry plus external thermal insulation composite system (ETICS).
A thicker masonry wall combined with ETICS usually only makes sense if achieving KfW 55 or better is the goal; for that, a 42.5cm (17 inches) masonry wall plus 12cm (5 inches) ETICS is typical.

Stefanoi schrieb:
How does it look price-wise? → if you plan a thicker wall and use less ETICS?

As mentioned before, for a "normal" house size of around 140 m² (1506 ft²), the additional cost is approximately 6,000 euros. By comparison, a 36.5cm (14 inches) solid masonry wall versus a 17.5cm (7 inches) wall plus 12cm (5 inches) ETICS is roughly cost-neutral.

Stefanoi schrieb:
Currently, our new build is planned with 24cm (9.5 inches) Poroton plus 16cm (6 inches) ETICS

Why is that?

Kind regards

@Bauexperte

At the moment, it’s because the architect says so —
I’m trying to find out through my many questions whether there are alternatives to the current plan without making the costs skyrocket.

A KfW 55 standard is planned.

Best regards

Stefanoi schrieb:
,,, whether there are alternatives to the current plan without causing costs to skyrocket --> a KfW 55 standard is being considered.

Separation of powers is usually the better approach.
However, the complex relationship between the building structure and the building services engineering must not be overlooked when aiming for an overall cost-effective solution. Initial investment, or the debt service associated with it, must be in a balanced ratio to operating expenses. Even a KfW 55 standard can potentially lead to an economic imbalance.

Best regards

Hello,

Stefanoi schrieb:
currently because the architect says so -->
I’m trying to find out through my many questions if there are alternatives to the current plan without causing costs to skyrocket --> a KFW 55 is planned.

For a conventional house build, you should expect to spend about 20,000 to 25,000 euros more to realize a KFW 55 energy-efficient house. This additional cost results from thicker masonry, stronger insulation, and a lot more technical equipment. So, as €uro probably suggests, the question of cost-benefit ratio arises.

I have often debated this with our structural engineer, and we largely agree that the predetermined focus on the KfW standard should not be the be-all and end-all. If a single-family home is built according to today’s current technology and regulations, it is by no means a bad house; it is important that the building envelope meets the values of a KFW 70 energy-efficient house.

The insulation and technical frenzy demanded from Brussels is another matter; after all, those gentlemen there don’t pay the bill. The lower the target goal — in this case KFW 55 — the more money has to be invested, and therefore not only the question of amortization of the required funds should be scrutinized but also personally whether 1 or 2 percentage points of cheaper financing are really worth all the technical complexity. Is a house built to meet current energy-saving regulations really worse?

I therefore always recommend to our clients to adapt the building envelope including glazing to KfW 70 standards (without external thermal insulation composite systems). I encourage the use of renewable technology — where possible a ground-source heat pump, alternatively an air-to-water heat pump, and definitely the installation of a ventilation system. With these measures, a solid and durable single-family house can be realized, where future occupants won’t feel like they are living inside a technology-heavy plastic shell.

In the coming years, many new technologies will enter the market, ranging from small wind turbines for the roof to storage-capable modules for electricity. When we reach that point — and the above recommendations were considered during construction — a later conversion to a self-sufficient house is feasible. I am confident that there will again be plenty of subsidies to apply for, and — perhaps even more importantly — by then the private budget will have recovered from the efforts of today’s new builds.

Best regards

First of all, thank you €uro and Bauexperte for the clear and understandable explanation.

Now, I am curious about what kind of building envelope should be aimed for?
The planned 24 cm (9.5 inches) plus 16 cm (6.3 inches) external thermal insulation composite system (ETICS) seems to me to have a bit less masonry and too much insulation.

My problem is that I don’t really have much knowledge about all this.

Would it be possible to explain the advantages and disadvantages of a thicker wall with less insulation in comparison?

Thank you very much in advance.