ᐅ Installation level including insulation – impact on exterior wall insulation?

Hi,

As part of my renovation project, the exterior wall of the "original building" will be insulated with 10cm (4 inches) mineral wool insulation boards (WLG035).
The exterior wall is a 24cm (9.5 inches) wall made of Liapor blocks.

So far, there was only internal insulation with 5cm (2 inches) polystyrene.

For the renovation, I now want to add an installation layer on the interior wall. In one area because I need to (heating pipes with insulation >> 10cm (4 inches)) and in another area because I hope the electrical installation will be much easier instead of chasing channels, etc. Structural considerations must also be kept in mind here. Until now, everything was contained within the 5cm (2 inches) polystyrene.

That means I want to add an installation layer of 4cm (1.5 inches) and 10cm (4 inches) thickness onto the interior wall, which will also be insulated (also with a mineral-based insulation material) + 15mm (0.6 inches) OSB + 12.5mm (0.5 inches) drywall.

Is there anything to consider or clarify regarding the insulation on the exterior wall? Or can I proceed without any issues?

I have read various reports about "dew point shift," etc., and am therefore uncertain...

Regards,
Chris

Flitz86 schrieb:

As part of my renovation project, the exterior wall of the existing building will be insulated with 10cm (4 inch) mineral wool boards (WLG035).

Why insulate so poorly?

Flitz86 schrieb:

That means I want to install a 4cm (1.5 inch) plus 10cm (4 inch) thick installation layer on the interior wall, which will also be insulated (also with a mineral-based insulation material) + 15mm (0.6 inch) OSB + 12.5mm (0.5 inch) drywall.

And here’s the question: what’s the point of interior insulation when you’re already insulating from the outside?

I might need to go into a bit more detail.

I have added an extra floor to part of the building (timber frame, yellow area). There is already a 60mm (2.4 inches) deep installation cavity planned here.
The load-bearing wall between the yellow and gray areas (gray-yellow dashed) is also made of 240mm (9.4 inches) Liapor blocks with a timber frame built on top. The blocks are no longer exposed to the exterior.
Green: Here are two dormer windows with an internal cavity wall that will also be insulated. The exterior wall is Liapor. It couldn’t be done differently due to the parapet height and other constraints.
In the gray-red dashed area, the roof continues. The roof itself is insulated. Below that is a heated space.

For the red-marked area, I need to create a cavity wall/installation cavity because heating pipes and water lines run there.

My question concerns the adjacent area (actually the entire gray area).

My intention is less about adding internal insulation and more about having a clean installation cavity. Those familiar with Liapor blocks know they are not easy to modify. Also, this approach means I don’t have to worry about structural issues.
Additionally, all rooms would have the same wall structure (OSB + drywall).

Why am I insulating only 10cm (4 inches) on the outside?
Because that is what the energy consultant calculated.

The correct approach would be:
Likewise, I would then have the same wall lining on the inside of all rooms (OSB + drywall).

Flitz86 schrieb:

My intention isn’t so much to achieve something with internal insulation but rather to have a clean installation surface.

I understand wanting a clean installation surface. You can simply skip internal insulation if it doesn’t serve any purpose anyway.

Flitz86 schrieb:

Why am I insulating only 10cm (4 inches) on the outside?
Because that’s what the energy consultant calculated.

So it’s the minimum insulation. As a tip: The fixed costs like labor, scaffolding, render, etc., are there anyway. A thicker insulation only adds marginally to the overall costs (a few percent extra), since everything else remains the same. That’s why I asked.

Regarding the dew point shift: ubakus – you can plan a lot yourself there ==> but it looks bad with internal insulation unless you take additional measures (or you just leave out the internal insulation).

only with air cavity

with internal insulation

Ok, thanks for the tip. I entered my proposed wall construction. With the insulation in the service cavity, my U-value is slightly better than without...

Basically, my question is not about whether this approach makes sense or not, but more about:
Could this cause any unwanted effects or lead to problems?

The OSB interior wall is also not designed as a vapor barrier. That means electrical outlets and openings are not sealed airtight...