Hello dear community,
Although this topic has been discussed in several posts before, long-term experiences are missing here.
I am currently planning a 150 m² (1,615 sq ft) new build with a basement. We have now narrowed down our choice to two builders who differ fundamentally in their building materials.
The house is planned to be built without insulation, using a monolithic construction method. One builder wants to use aerated concrete or Poroton blocks (wall thickness 36.5 cm (14 inches)), while the other plans to use a solid precast wall made of expanded clay aggregate with a wall thickness of 41 cm (16 inches). We are now a bit uncertain because the thermal transmittance (U-value) given by the builders differs greatly: 0.21 W/m²K for Poroton and 2.2 W/m²K for expanded clay. Both assure us that the houses meet the KFW 55 standard.
I am unclear how the U-values can differ so much or whether other factors, such as the mortar used with Poroton, are included. The insulation in the attic and the windows (triple glazed) seem comparable in both cases. Are there any long-term experiences in this forum with solid walls made from expanded clay?
Can you tell me whether a similar energy balance for heating can be expected based on the KFW 55 standard?
Our concern is that with poor insulation and a heat pump, we might not achieve sufficient room heating or end up with very high heating costs due to additional electric heating rods.
Best regards,
Sven
Although this topic has been discussed in several posts before, long-term experiences are missing here.
I am currently planning a 150 m² (1,615 sq ft) new build with a basement. We have now narrowed down our choice to two builders who differ fundamentally in their building materials.
The house is planned to be built without insulation, using a monolithic construction method. One builder wants to use aerated concrete or Poroton blocks (wall thickness 36.5 cm (14 inches)), while the other plans to use a solid precast wall made of expanded clay aggregate with a wall thickness of 41 cm (16 inches). We are now a bit uncertain because the thermal transmittance (U-value) given by the builders differs greatly: 0.21 W/m²K for Poroton and 2.2 W/m²K for expanded clay. Both assure us that the houses meet the KFW 55 standard.
I am unclear how the U-values can differ so much or whether other factors, such as the mortar used with Poroton, are included. The insulation in the attic and the windows (triple glazed) seem comparable in both cases. Are there any long-term experiences in this forum with solid walls made from expanded clay?
Can you tell me whether a similar energy balance for heating can be expected based on the KFW 55 standard?
Our concern is that with poor insulation and a heat pump, we might not achieve sufficient room heating or end up with very high heating costs due to additional electric heating rods.
Best regards,
Sven
Ybias78 schrieb:
Who is supposed to shout at our place? We live in a village, so you rarely meet anyone. The plot is almost 1,500 m² (16,000 sq ft) and the house will be built about 15 m (49 ft) from the property boundary.Then why are you even asking?
11ant schrieb:
I live in a pumice stone region, where Bisotherm is also very popular (monolithic as far as I know, without excessively thick walls).A general contractor nearby is using Bisotherm’s Bisoplan. I haven’t found much information about this block here in the forum. Are there more users with experience? Who has used it and can share their feedback?
Georgie schrieb:
A general contractor nearby uses Bisotherm’s Bisoplan. I haven’t found much information about this block here in the forum. It’s similar with pumice blocks as with local builders, or aerated concrete blocks that aren’t branded Hebel or Ytong. Where exactly are you building?
Georgie schrieb:
Are there more experiences? Who has used it and can share their reports? I assume the pumice in all the houses I’ve lived in so far came from Bartsch (which no longer exists) and was installed by my friend Heini Kochhäuser, *smile*. When I chat with home builders during my walks in construction areas, it’s usually brief and only with a few. Riffer is known locally, and you can easily recognize Bisotherm by its “pink pumice.” However, around here it’s about as common as blocks from KLB or Meurin. In a volcanic rock hotspot, white masonry is rarely used. At most, when a building company goes through a generational change and the junior insists on doing things differently than the senior, porous brick then has a chance. In neighborhoods with many newcomers, red brick masons are stronger, but among the locals, pumice still holds the largest market share. I’m not building at the moment, but Bisotherm would probably be among my top choices. If anyone here filled a building gap with calcium silicate blocks, it would probably be the talk of the town at the bakery or pharmacy.
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