ᐅ Lightweight expanded clay aggregate (LECA): Advantages and Disadvantages, Thickness, Suppliers

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!

We had our old house built in 1995 as a prefabricated house made of expanded clay aggregate.
The walls were manufactured in the factory and only assembled on site.
The house performs very well thermally (heating costs around 800-1000€ per year) and has excellent sound insulation.
Our current house is also made of expanded clay aggregate, filled bricks 42cm (16.5 inches) thick (Liaplan), also very good.
Local brickworks and a regional construction company, everything was transparent.
However, rule number 1 applies: the construction company should use the materials they are familiar with.
Both construction companies we worked with used only expanded clay aggregate; for other materials, we would have had to find different companies.

PS: Try to find a local building expert and talk to them for at least an hour. They know the bad apples as well as the reliable ones. If the expert seems suitable, they should also accompany you during the construction process, which we did as laypersons as well.

Nida35a schrieb:

Our current house is also made of expanded clay, 42cm (17 inches) filled bricks (Liaplan),
everything is good as well.

Thank you for your message. Do I understand correctly that the first house was a prefabricated house made of expanded clay, and the second house was built with filled bricks made from expanded clay, laid brick by brick?

How thick were the walls in your first house, and was there anything negative that made you choose a different method the second time?

I hope that you are building the duplex yourselves and not each taking one half individually, otherwise it will be quite an adventure with stories to last a lifetime. In that case, I would coordinate closely with your duplex neighbor. Otherwise, chaos is inevitable. So I’m hoping that you are building the entire duplex yourselves. If not, it will certainly be an interesting time for you that will require a lot of patience.

Yes, the second house is built brick by brick. The company manager had software that calculated the dimensions and quantities of bricks based on the floor plan. He claimed it was so accurate that the maximum waste from construction would only be about one wheelbarrow, which turned out to be true, even though it was actually an employee who handled that. The first house had walls approximately 25-30cm (10-12 inches) thick, built by a prefabricated house company, while the second was constructed by a small family business. In which postal code area are you building?