ᐅ Insulation of the foundation base with thermal conductivity class 025 (WLG 025)

Created on: 25 Jun 2021 10:32
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neo-sciliar
Hello everyone,

according to the building plan, I am supposed to insulate the edge of the foundation slab (plinth) with 6cm (2.4 inches) WLG 025 insulation.
1.) I can’t find any such boards. Most only have WLG 035. Do you have any tips on where I can get these?
2.) Should they be fully glued, fixed with dowels, or both?

Best regards,
sciliar
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neo-sciliar
25 Jun 2021 11:05
Okay... logically: 6 / 0.25 * 0.35 = 8.4. Therefore, the question is whether 8 cm (calculations suggest it should be 8.4 cm) is sufficient, or if it needs to be 10 cm. The thermal resistance would then decrease from 2.4 to 2.29 m²K/W at 8 cm, and the U-value would correspondingly increase from 0.41 to 0.44.
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Lumpi_LE
25 Jun 2021 12:05
The question is more whether it will then protrude... What does the construction look like? PUR foam is available for interior and exterior use; you just need to search a bit more.
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neo-sciliar
25 Jun 2021 12:34
We have a baseboard (Z-profile) that extends 12cm (5 inches) beyond the floor slab. This leaves space for 8cm (3 inches) of insulation and then plaster. With 10cm (4 inches), it would be tight. Hence the question (above calculation) whether 8cm (3 inches) of insulation with WLG035 is sufficient.
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Lumpi_LE
25 Jun 2021 14:12
Base plaster is usually about 5 to 10 mm (0.2 to 0.4 inches), so 8 cm (3 inches) is not an issue and is generally sufficient in practical construction.
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nordanney
25 Jun 2021 16:33
@neo-sciliar: Your construction site is in Rhineland-Palatinate, right? If it’s not too far, you might want to check out smartbau in Nettetal. They are a second-choice supplier (which can mean the panels are sometimes about 1cm (0.4 inches) too short or too long) and they sell only PUR/PIR insulation. Currently, they can deliver a large quantity at unbeatable prices.