ᐅ Filling a hole in an interior wall with XPS insulation boards?

Hello,

since the gutter in the cavity wall has been more or less leaking for years, I would now like to move it completely outside in front of the brickwork. The insulation will be replaced because it is wet.

There are tiles on the terrace, which I also want to extend over the cavity wall (old gutter) into the new gutter. My idea was to glue XPS boards inside the cavity wall and apply a waterproofing slurry on top, possibly followed by screed, tile adhesive, and tiles. Or what would you suggest?

I don’t understand anything at all.

What kind of partition wall—between exactly what?
Terrace, roof, partition wall—all related to drainage?
What does the picture show?

... thinking, thinking

I would prefer double-wall masonry where a gutter is installed for drainage. However, this is not watertight and is placed outside the masonry. Therefore, I need to seal the opening in the double-wall masonry and allow overflow. The rest is a terrace.

Ok.
So, between two walls there is this channel – a gutter. It is supposed to be closed off and replaced with a standard gutter.

Please show some photos of it. I can’t imagine how you plan to hang a normal gutter there.

Regarding the insulation: if it is wet, it should be completely removed first.
I find it hard to imagine how you would glue XPS panels in place, especially since, for example, how would you glue a 10cm (5 inches) thick panel into a 10cm (5 inches) gap? Also, how many meters exactly is it down to the ground? I suspect you will neither be able to remove the old insulation nor carry out your plan as intended. Perhaps you could reinstall mineral wool insulation, hoping that with an air gap it will settle far enough down. Especially with cavity walls, mortar residues often stick out, so you will very likely not find smooth surfaces on both sides of the walls.

However, the situation is still not 100% clear to me.

Michel56 schrieb:

Tiles lie on the terrace, which I also want to extend over the partition wall (old gutter) into the new gutter. My idea was to glue XPS panels inside the partition wall and then apply a sealing slurry, possibly screed, tile adhesive, and tiles on top. Or what would you do?

The dimensions are 4 m (13 ft) in length and about 1.20 m (4 ft) in height. Therefore, it would still be manageable without a ladder. During the last renovation, gutter channels were installed or glued on, but they are not really watertight.

The idea was to cut the XPS boards to size and apply adhesive on all sides accordingly. Instead of a 30 cm (12 inch) wall thickness, the wall was built with 36 cm (14 inch), so I could also attach the 6 cm (2.4 inch) wall overlap within the double-layer masonry using XPS boards. This should make slipping downward almost impossible. Above the XPS boards, I was considering screed and/or concrete plus tiles. However, I am not a professional.

🤨
It is unfortunately becoming increasingly unclear. We need photos—showing the overall situation, not close-up shots of the gutter.
Possibly also schematic drawings from above and from the side, including measurements and a site plan.