Plastering of internally mounted roller shutter box with lime-cement plaster

Hello,

we received our windows with inwardly located roller shutter boxes.

The Styrofoam insulation is not completely flush with the masonry but is recessed by about 15 mm in some places.

The construction company says we should install Styrodur, the window supplier says the roller shutters can be plastered directly (at that time I did not know that they were not flush with the masonry). Now I wanted to get the contact number of the plasterer but I don’t know if I can reach him in time.

What do you think? Styrodur on top? How thick can the lime-cement plaster be?

That is not a problem at all. It will simply be plastered over. Up to 2cm in a single layer should be doable, otherwise in multiple layers.

I would level the whole thing with Styrodur and then create a contact layer using adhesive reinforcing mortar.

Please ensure that the box can still be opened later with as little damage as possible. At some point, it will need to be opened.