ᐅ Exterior wall with ETICS or exterior wall with lightweight render?

Hello everyone,

a great forum. I have already gained a lot of useful background information. THANK YOU!

We want to build a 1.5-story house, 135m² (1,453 sq ft), with a gas condensing boiler and solar thermal collectors, underfloor heating on the ground and upper floors, and a chimney flue. Two rooms on the upper floor, as well as the living room and guest room, face south. The plot (750m² (8,073 sq ft)) is located in a lightly developed residential area adjoining farmland. KfW 70 energy efficiency standard is not planned (or is it an option?).

Currently, I am wondering whether to build with:

24cm (9.5 inches) porous hollow bricks plus 8.0cm (3 inches) insulation (polystyrene rigid foam boards), reinforcing layer, and finishing render

or with

36.5cm (14 inches) porous hollow bricks and 2.0cm (0.8 inches) lightweight plaster with fiberglass mesh reinforcement.



Could someone possibly give me a general recommendation or explain the difference? Is the first option sufficient? Do I understand the second option as a monolithic construction where no additional insulation is needed due to the brick thickness?

Unfortunately, we have experienced mold and moisture damage in our previous apartment. I’ve read repeatedly that the first option often causes problems with moisture diffusion. For example, we always sleep with the window open at night. What option would cause us fewer concerns in this respect? Would a ventilation system then be a must?

I know I’m not a professional, and I understand that this can’t be generalized, but I hope you can provide a few tips or information.

Thank you very much and best regards
Marcel

Hello Marcel,

malu82 schrieb:

a great forum. I’ve already gained a lot of additional information. THANK YOU!

You should actually know that there is no such thing as "the" system or "the" brick.

malu82 schrieb:

For example, we sleep with the window open every night.

That is neither wise nor healthy—especially from autumn to spring!

Regards, Bauexperte

Bauexperte schrieb:
Hello Marcel,


You should actually know that there is no single “system” or “block”.


That is neither smart nor – especially from autumn to spring – healthy!

Regards, Bauexperte

Hello Bauexperte,

Unfortunately, I don’t know, which is why I’m asking.

Thank you for your advice regarding what is smart or healthy. I will discuss this with my wife.

Despite the information that there is no single “system” or “block,” do you have any tips, recommendations, advantages, or disadvantages?

How you decide to do it is, of course, up to you... I have nothing against external thermal insulation composite systems (ETICS), but if you can build with 36.5cm (14.4 inches) walls, I would go for that...

Whatever you choose, your house needs to be airtight or should become airtight if you plan to save energy costs in the coming years...

A ventilation system should actually be mandatory for new buildings... I definitely wouldn’t buy or build a house without a mechanical ventilation with heat recovery system...

By the way, leaving a bedroom window open is not a solution to remove moisture from the whole house... it might only help with moisture in the bedroom itself...

However, mold and dampness can only be eliminated by both heating and ventilating together... doing just one is not enough...

And that’s exactly what matters to me... I just can’t see any differences or simply don’t know them...

Of course, you want to save on energy costs... but is the difference between the two options really that big..?

The difference is more philosophical in nature... both options result in a similar indoor climate, temperatures, and energy costs.