ᐅ Installation level including insulation – impact on exterior wall insulation?
Created on: 26 Feb 2024 15:01
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Flitz86
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
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
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nordanney26 Feb 2024 19:42Flitz86 schrieb:
Ok, thanks for the tip. I entered my proposed wall construction. For me, the U-value with the insulation in the service cavity is slightly better than without it...
Basically, my question is not "is it sensible or not," but rather:
Could this cause any unintended effects or lead to problems?
The OSB interior wall is not designed as a vapor retarder. That means electrical outlets and holes are not sealed airtight... … that’s why it will get damp. See ubakus. I already showed you that specifically.
SoL schrieb:
Take a look at the colorful images in the post above yours and think about what these water droplets might represent... When I entered my wall construction, neither of those "droplets" appeared.
I assume the droplets indicate the dew point location here? Please correct me if I’m wrong...
nordanney schrieb:
… that's exactly why it will get wet. See ubakus. I showed you that on purpose.I am a complete beginner when it comes to the U-value topic. But I assumed that a lower U-value is better than a higher one (speaking generally). In my simulation, no droplets were visible in either case.
Why can it get "wet" with the version that has insulation on the inside?
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nordanney26 Feb 2024 21:33Flitz86 schrieb:
I suppose the drops indicate where the dew point would be? Please correct me if I’m wrong...Correct. Flitz86 schrieb:
I’m a complete beginner when it comes to U-values. But I assumed that a lower U-value is better than a higher one (generally speaking).
In my simulation, I didn’t see any drops either. The U-value indicates the insulation quality of the wall. However, it has absolutely nothing to do with moisture within the insulation layer. Simply put: With interior insulation, the dew point shifts toward the inside surface of the exterior wall. Since your installation layer is not airtight, moist air passes through the interior insulation—which is just mineral wool—and condenses on the cool interior surface of the exterior wall. This doesn’t happen overnight but develops gradually over time.
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