ᐅ Are cracks in the plaster to be expected with monolithic wall construction without external thermal insulation composite systems (ETICS) / external wall insulation?

Hello everyone,

I am currently planning my first single-family home, a roughly 250m² (2,690 sq ft) bungalow for my family and me. By "planning," I mean that I am researching the available building materials, how houses are generally constructed, and so on.

Here is a rough 3D concept.

My father is somewhat of a veteran in this field and has built several family single-family homes himself, acting as a kind of site manager or planner. He is an engineer; I work in IT. I do a lot of research, while he tends to stick to the motto "trust in proven methods." So we often have differing opinions. That’s the background 🙂

I recently came across Ytong because I like the idea of a monolithic exterior wall without many layers or unnecessary complexity. I am interested in the 425mm (16.7 inches) wall thickness.

I would like to have external venetian blinds on all windows and sliding doors and have seen that their installation can be done like this, for example:

I assume there are finished, insulated boxes available for this purpose, like these here:

and that you can then plaster over the joints with reinforcing mesh without breaking the building material, resulting in a smooth and clean surface.

My father says, “For heaven’s sake... get 365mm (14.4 inches) Poroton T7 or Ytong if you prefer, and install a slim 60mm (2.4 inches) external thermal insulation composite system (ETICS) over the masonry and shutter boxes. Otherwise, you’ll get thermal bridges at the boxes and the plaster will crack there over the years.”

He also worries a lot about integrating the 3.5-meter (11.5 feet) wide windows and sliding doors with the venetian blinds, how to incorporate the boxes into the masonry and lintels, etc. I think: this can’t be rocket science nowadays? You see it everywhere, it shouldn’t be so difficult, right?

I would like to trust his experience—he certainly has plenty—but I also believe that building materials and techniques can evolve. Since you occasionally read about monolithic construction and venetian blinds or roller shutter boxes aren’t uncommon, I wonder if everyone just accepts plaster cracks or if this is perhaps no longer an issue today?

Thank you very much!

Steffen_S schrieb:

I am willing to trust his experience—after all, he has plenty of it—but I also believe that materials and techniques can evolve. Since you still occasionally hear about monolithic construction and shutter boxes or roller shutter housings are not uncommon, I wonder if they all accept plaster cracks or if that might simply not be an issue anymore nowadays?

If properly installed, everything works fine.

P.S. The floor plan looks a bit like an office floor with a meeting room at the end. Terrible...

Looks like a video game level. Or a school.

I’ll remove the floor plan images again – apparently, it makes it harder to focus on the actual question of the thread, which was not “What do you think of my floor plan?” 🙂

The image was meant to show that there will be many large windows and glass elements, requiring lots of wide external blinds boxes to be integrated into the walls accordingly.

What I’m really interested in is the issue of plaster cracks or problems with thermal bridges in a monolithic wall construction without external thermal insulation composite system (ETICS) / external wall insulation – the rest is just a matter of personal taste.

If installed properly, everything works well.

Can this be understood to mean that no plaster cracks are to be expected even if the external insulation is left out? What do you have to pay special attention to in that case?

Steffen_S schrieb:

Can it be interpreted that no plaster cracks are to be expected even if the external thermal insulation composite system (ETICS) is omitted? What specific points should be considered then?

You need to find skilled craftsmen and have a suitable plan to work from. You don’t have to worry about anything yourself—that’s what professionals are for.

Definitely not Poroton 365 T7. How did he come up with something like that?