Hello house building forum,
Unfortunately, I haven’t found a proper solution to my problem yet and hope to get some advice, thoughts, or ideas from you.
We are currently still building our new single-family house (Kfw 60 standard). Unfortunately, I only started dealing with thermal bridges very late. I got a thermal bridge catalog and focused primarily on the building components involved. I know this should have been considered during the planning phase. That’s just how it is. Since we are self-builders, I was still able to reduce some thermal bridges myself (e.g., windows, ring beam, floor beams). Our house is built on strip foundations with plinth insulation. The walls are made of aerated concrete (thermal conductivity 0.090) and are directly mortared onto the 16 cm (6 inch) thick slab. For floor insulation, we plan to use 10 cm (4 inch) of rigid phenolic foam from Kingspan (thermal conductivity 0.021).
Now I have seen in my thermal bridge catalog that the strip foundations represent a thermal bridge. The slab underneath and the strips on both sides should/could have been insulated. Since it’s difficult to excavate around my house again, I’m now considering whether it makes sense to at least insulate the full strips from the outside. Since we still need to install a ground heat exchanger, the strip foundations will be fully exposed during that. In this context, I could apply insulation (e.g., extruded polystyrene foam) there. A 6 cm (2.4 inch) insulation would cost me about 300 EUR. However, the catalog specifies 16 cm (6 inch). If this is worthwhile, I would do it. What thickness would you recommend? What are your thoughts on this?
Thank you very much and best regards
Fello’w.
Unfortunately, I haven’t found a proper solution to my problem yet and hope to get some advice, thoughts, or ideas from you.
We are currently still building our new single-family house (Kfw 60 standard). Unfortunately, I only started dealing with thermal bridges very late. I got a thermal bridge catalog and focused primarily on the building components involved. I know this should have been considered during the planning phase. That’s just how it is. Since we are self-builders, I was still able to reduce some thermal bridges myself (e.g., windows, ring beam, floor beams). Our house is built on strip foundations with plinth insulation. The walls are made of aerated concrete (thermal conductivity 0.090) and are directly mortared onto the 16 cm (6 inch) thick slab. For floor insulation, we plan to use 10 cm (4 inch) of rigid phenolic foam from Kingspan (thermal conductivity 0.021).
Now I have seen in my thermal bridge catalog that the strip foundations represent a thermal bridge. The slab underneath and the strips on both sides should/could have been insulated. Since it’s difficult to excavate around my house again, I’m now considering whether it makes sense to at least insulate the full strips from the outside. Since we still need to install a ground heat exchanger, the strip foundations will be fully exposed during that. In this context, I could apply insulation (e.g., extruded polystyrene foam) there. A 6 cm (2.4 inch) insulation would cost me about 300 EUR. However, the catalog specifies 16 cm (6 inch). If this is worthwhile, I would do it. What thickness would you recommend? What are your thoughts on this?
Thank you very much and best regards
Fello’w.
N
nordmann-15 Aug 2009 14:58Hello Fellow
I would use Neopor insulation (11 cm (4.3 inches)).
Excavate around 80-90 cm (31-35 inches) of the foundation and attach the panels to the concrete, making sure the panels fit together tightly.
I would use Neopor insulation (11 cm (4.3 inches)).
Excavate around 80-90 cm (31-35 inches) of the foundation and attach the panels to the concrete, making sure the panels fit together tightly.
Hello fellow builder,
It depends on whether you need to meet legal requirements. Depending on the canton, there are strict regulations regarding the overall U-value.
For example, if you insulate the exterior facade more strongly, you can theoretically use thinner insulation at the base and compensate for the lower insulation value in the base area with the better U-value of the facade. Ultimately, the energy certificate (energy regulation) will specify the minimum insulation requirements.
If you want to be on the safe side, you should compare the lambda values of the insulation materials. The lower the lambda value, the thinner the insulation can be, but the more expensive the insulation becomes. You might actually save money by choosing thicker base insulation with a higher lambda value. If you like, I can send you an Excel file to calculate the U-values.
Where exactly are you building?
Best regards
It depends on whether you need to meet legal requirements. Depending on the canton, there are strict regulations regarding the overall U-value.
For example, if you insulate the exterior facade more strongly, you can theoretically use thinner insulation at the base and compensate for the lower insulation value in the base area with the better U-value of the facade. Ultimately, the energy certificate (energy regulation) will specify the minimum insulation requirements.
If you want to be on the safe side, you should compare the lambda values of the insulation materials. The lower the lambda value, the thinner the insulation can be, but the more expensive the insulation becomes. You might actually save money by choosing thicker base insulation with a higher lambda value. If you like, I can send you an Excel file to calculate the U-values.
Where exactly are you building?
Best regards
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