ᐅ Attic Conversion – Is Adding Insulation to the Knee Wall / Short Wall Necessary or Beneficial?

Hello,
we are currently renovating our roof space. Two levels (attic + loft) will provide 160 sqm (1,722 sq ft) of living area.

On the first level, we built a 40 cm (16 inches) high concrete knee wall, on top of which a 60 cm (24 inches) high laminated timber beam was installed to raise the roof.

Current structure of the concrete knee wall:

The area outside the added purlin will be insulated during exterior plastering work to match the level of the rest of the exterior facade.
About the remaining masonry:
The house was built in 1986 using 36.5 cm (14 inches) Poroton bricks with 2 cm (0.8 inches) lightweight plaster. No external facade insulation will be added for the time being, meaning the knee wall’s exterior must remain as it is.

Is the existing knee wall insulation (pre-built Poroton + Heraklith wood fiber board + lightweight plaster) sufficient in relation to the rest of the masonry (36.5 + 2), or would it be advisable to add insulation on the inside? I’m mainly concerned about preventing a shift of the dew point and avoiding later moisture or mold buildup on the interior concrete surface.
If additional internal insulation is recommended, what type and method would be best?

Maybe also interesting:
The new roof has 20 cm (8 inches) of insulation between rafters plus 10 cm (4 inches) of wood fiberboard insulation above the rafters.
Underfloor heating will be installed throughout the entire lower area of the apartment.

Thanks in advance for your advice!
Best regards

Hmm, over 480 views and no one dares to respond?

This might be related to the fact that this question can only be answered after a thorough assessment of the current situation, followed by an analysis based on professional expertise. Consult a structural engineer or similar specialist and ask them to handle it. That is money well spent.

Good luck

K1300S

You expressed that well, I just wonder what use a structural engineer would be for me here?

Hello,

killbill schrieb:
...
I’m just wondering what use a structural engineer would be here?

I hope this question is not serious?

You want to add an extension on top of an existing building from 1986, for which the structural calculations were made based on its actual use. Now you are changing the building envelope and adding several square meters that will be used regularly. Don’t you agree that a structural engineer should recalculate whether the existing structure is sufficiently secured for the additional loads?

I was already wondering from your original post whether you really want to carry out the renovation without professional expertise involved...

Best regards, Bauexperte

Those who can read are clearly at an advantage. The elevation has long since been completed with the architect, building permit / planning permission, structural design, and structural verification! Currently, we are working on the interior construction, and my post is solely about the insulation or non-insulation of the knee wall! I just thought I’d provide some background to better describe the surrounding circumstances.