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!