ᐅ Lightweight expanded clay aggregate (LECA): Advantages and Disadvantages, Thickness, Suppliers
Created on: 17 Jan 2023 10:29
M
Mar_Mar
Good morning everyone!
My husband and I (both rather paper people) are planning to build a fairly large semi-detached house and are navigating through the jungle of options. We want a solid construction and have spoken with various suppliers. The available options regarding blocks are aerated concrete, Poroton, and expanded clay (prefabricated), all 36.5cm (14.4 inches) thick and built as monolithic walls. Of course, each consultant believes their own material is the best, so I would be interested in your opinions and experiences.
“Actually,” we would rather not build with aerated concrete/Ytong because our naive assumption about moisture absorption (sponge effect) during construction and later when drying out the house seems negative. However, I can understand the argument for its easy workability.
Poroton would be our “favorite,” but I get the impression that many companies really resist using it because of a lot of waste, losses during transport, and comments like “you don’t notice a difference,” etc. Then there is also the split between filled and unfilled blocks.
And then there is expanded clay. Our “new favorite with a question mark.” It seems very interesting because it somehow combines the best of both worlds: dry straight from the factory, quick, even cheaper. BUT if it’s so good, why don’t more people build with it and why are there relatively few suppliers? That makes us skeptical. I’ve read and researched a lot that it often cracks and that its insulation properties are not the best compared to Poroton. We were told that an unfilled 36.5cm (14.4 inches) Poroton block is comparable in properties to a 42cm (16.5 inches) expanded clay block.
We are lost in this jungle of U-values, lambda, etc. Can you support us?
By the way: insulation is more important to us than soundproofing.
Thanks so much!
My husband and I (both rather paper people) are planning to build a fairly large semi-detached house and are navigating through the jungle of options. We want a solid construction and have spoken with various suppliers. The available options regarding blocks are aerated concrete, Poroton, and expanded clay (prefabricated), all 36.5cm (14.4 inches) thick and built as monolithic walls. Of course, each consultant believes their own material is the best, so I would be interested in your opinions and experiences.
“Actually,” we would rather not build with aerated concrete/Ytong because our naive assumption about moisture absorption (sponge effect) during construction and later when drying out the house seems negative. However, I can understand the argument for its easy workability.
Poroton would be our “favorite,” but I get the impression that many companies really resist using it because of a lot of waste, losses during transport, and comments like “you don’t notice a difference,” etc. Then there is also the split between filled and unfilled blocks.
And then there is expanded clay. Our “new favorite with a question mark.” It seems very interesting because it somehow combines the best of both worlds: dry straight from the factory, quick, even cheaper. BUT if it’s so good, why don’t more people build with it and why are there relatively few suppliers? That makes us skeptical. I’ve read and researched a lot that it often cracks and that its insulation properties are not the best compared to Poroton. We were told that an unfilled 36.5cm (14.4 inches) Poroton block is comparable in properties to a 42cm (16.5 inches) expanded clay block.
We are lost in this jungle of U-values, lambda, etc. Can you support us?
By the way: insulation is more important to us than soundproofing.
Thanks so much!
W
WilderSueden18 Jan 2023 09:38Mar_Mar schrieb:
This is still an issue that needs to be clarified. “Actually,” we don’t want any ventilation system, which, for example, Lec***** wouldn’t install at all. We currently have a passive window rebate ventilation and find it terrible (whistling, dirty, drafty). But I think in the long run it might make sense after all. At least you can make preparations. Here you are making the mistake of generalizing from one specific type of ventilation to all ventilation systems. Personally, I wouldn’t even call window rebate ventilation a real ventilation system; it’s just a deliberately leaky window.
Basically, I wouldn’t build a house today without a ventilation system, even if it’s not legally required (at least not for KfW55 standard). We build well-insulated building envelopes and then end up ventilating the heat out through the windows. On top of that, relying on window ventilation is simply very inconvenient. When there’s no wind, the air tends to stagnate. When there is wind, it causes drafts throughout the house.
Mar_Mar schrieb:
Can anyone say something about the disadvantages of prefabricated lightweight expanded clay aggregate (LECA) components? For prefabricated parts made of LECA, the wall thickness is determined by the factory’s capabilities; we didn’t have any choice. The walls were not plastered, smooth like concrete on the inside, directly wallpapered by us, and on the outside, there was a 2mm (0.08 inches) textured render applied by the general contractor. You would need to check what the current situation is nowadays.
WilderSueden schrieb:
You’re making the mistake of generalizing from one type of ventilation to all ventilation systems. Personally, I wouldn’t even classify window rebate ventilation as real ventilation; it’s simply a deliberately leaky window 😉
Basically, I wouldn’t build a house today without some form of ventilation, even if it’s not required (at least not for KfW55 standard). We build highly insulated building envelopes and then end up losing heat through the windows by airing out. Also, ventilating with windows is just very uncomfortable. When there’s no wind, the air gets stagnant. When there is wind, it drafts through the house. You’re right, of course there is a difference, but that’s my first impression and experience when someone mentions mechanical ventilation. I still need to research the possible options… step by step 🙂
Therefore, I would also say it probably makes sense in general. You have to think long term, and eventually it might be difficult to sell the place because “oh no, they don’t even have ventilation” 😀
Nida35a schrieb:
For precast lightweight aggregate concrete elements, the wall thickness is determined by the factory’s standards; we didn’t have any choice.
The walls were not plastered,
the interior was smooth like concrete, and we applied wallpaper directly ourselves. The exterior had a 2mm (0.08 inch) textured plaster applied by the general contractor.
You would need to check how it is done nowadays. You have the choice of 36.5, 42, or 49 cm (14.4, 16.5, or 19.3 inches) thickness... somewhere I read that a filled 36.5 cm (14.4 inch) Poroton block is roughly equivalent to a 42 cm (16.5 inch) lightweight aggregate block, but to be honest... read it somewhere... by whom… no idea. That’s why I’m here 🙂
The exterior plaster is already applied at the factory, the interior is not.
Mar_Mar schrieb:
Looking at the values, one should definitely consider using a 42cm (17 inches) wall if building monolithically. We have 42cm (17 inches) solid masonry walls, @motorradsilke has 36.5cm (14.5 inches) solid masonry walls, and both of us live comfortably in our houses,
although her house is 11cm (4.3 inches) larger inside in both length and width 😱
WilderSueden schrieb:
We build highly insulated building envelopes and then ventilate the heat out through the windows. Either that, maybe,
cooling down 30-50 tons of bricks and floors doesn’t happen in 10 minutes – it doesn’t work in summer or winter,
we only ventilate the air (the smallest amount of heat) out.
Or a mechanical ventilation system with 90% heat recovery always has about a 10% heat loss...
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