Hello,
I am replacing windows and adding insulation to a house with aerated concrete walls and concrete slabs. One window opening extends all the way up to the intermediate slab but with a partition cast together with the slab. Above the old window, there was a wooden box with an armored shutter.
The new window will be mounted flush with the outside of the old wall below the partition, which is only about 5 cm thick (see picture).
In the "ceiling" of the window opening, there is a Heraklith board that I suspect covers an embedded steel beam.
The niche needs to be filled with something a bit more stable than insulation, and I'm considering if I can glue 5-10 cm Ytong and then something lighter (Tecterm, Multipor, etc.) the rest of the way?
The concrete partition is straight and not smooth, so probably anything will adhere. I'm considering cement mortar, tile adhesive, or Knauf SM700Pro? The latter is probably best for the plasterboard above, but I'm unsure if it will hold in the long run?
Will this work, or should I look for another solution? I'm not too keen on cutting out supports for an aerated concrete beam in the supports for the steel beam.
(apologies for the .pdf file, LibreCAD...)
