ᐅ Exterior wall insulation with ETICS (External Thermal Insulation Composite System). What thickness of rigid foam boards is recommended?

Hello everyone,

we are not quite sure how many centimeters of insulation with rigid foam boards make sense.

One developer says that the exterior wall accounts for 40% of the entire outer surface area of the house and recommends, in addition to strengthening the roof insulation, also reinforcing the external wall insulation.

The background is that we originally wanted to replace the 17.5cm (7 inches) Poroton bricks with ETICS (external thermal insulation composite system) from the construction specification with either a 36cm (14 inches) solid brick or a 24cm (9.5 inches) aerated concrete block with ETICS. Our developer (Heinz von Heiden, Hesse) advised us to save the extra cost on aerated concrete and instead invest in thicker insulation on the external walls. Is Heinz von Heiden’s argument correct?

In the construction specification, the insulation panels on the exterior walls have a thickness of 16cm (6.3 inches) and the external wall has a U-value of 0.19.

With an additional cost of around 2,500 euros, we would get 24cm (9.5 inches) of external insulation with a U-value of 0.14...

We are currently talking to several developers, and the one from Helma thinks this is nonsense. According to them, only the roof is important and should be strengthened, since the interior space of the house decreases with thicker insulation boards.

Question: What is your opinion on the THICKNESS of external insulation with rigid foam boards (no alternatives, this is really only about the thickness of the boards and whether the energy efficiency gain justifies the extra cost)?

Thank you in advance to everyone who can help.

Hello,

kanzler753 schrieb:
...we are not entirely sure how many centimeters of insulation is appropriate with the rigid foam boards.

What do you mean by appropriate? Minimal heat transmission losses, compliance with energy saving regulations, or cost-effective insulation thickness? It should also be questioned whether "rigid foam boards" are the best choice.

kanzler753 schrieb:
...Question: What is your opinion on the THICKNESS of the external insulation using rigid foam boards (no alternatives, it’s really only about the thickness of the panels and whether the efficiency gain justifies the extra cost)

This already suggests that a thorough initial assessment or concept development has likely not taken place.
When experiencing symptoms, ask 10 doctors. Result: 15 diagnoses and 20 treatments. However, without any guarantees and disclaimers.

Regards.

kanzler753 schrieb:

Our general contractor (Heinz von Heiden, Hessen) advised us,
Many thanks in advance to all helpers

Insulation probably won’t be a major concern here... there are other, more important considerations for you...
It’s quite surprising how people still think about certain builders in the year 2010...

Hello,

BauLine schrieb:
It is quite surprising how people still think about certain property developers in the year 2010...

...Ostrich policy?...

Kind regards