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

Mar_Mar schrieb:

Therefore, I would also say that it probably makes sense in principle. You have to think long-term, and eventually, we won’t be able to sell the house easily because “oh no, they don’t even have ventilation” 😀

Decentralized ventilators can also be retrofitted with relatively little effort.

Nida35a schrieb:

Cooling down 30-50 tons of stones and soil in 10 minutes is not possible, neither in summer nor winter. We only ventilate the air (which stores the least amount of heat).
Or a mechanical ventilation system with 90% heat recovery always has a 10% heat loss...

Well, manually ventilating three times a day with a complete air exchange means 3 air changes. The recommended air change rate is at least 0.5 per hour, which equals 12 air changes or 1.2 volumes of air lost.
This calculation also shows how impossible it is to achieve similar air quality with window ventilation. No one ventilates 12 times a day.

Mar_Mar schrieb:

And just because my neighbors have already gone ahead and signed, we won’t simply give in. If you look at it the other way, you could ask why they didn’t talk to us first. But that’s not the point, and everyone can do as they please. That’s how it should be. No one said it was too expensive for us.

Now don’t be ungrateful: You know the semi-detached neighbors and talk to each other. The not exactly typical but also not that uncommon semi-detached house builder has to come to terms with getting to know the buyer of the other half-plot within three years and “being allowed” to insulate the shared wall as an exterior wall until then. Besides, I have the impression that Schwabenhaus probably wouldn’t have suited you price-wise either (?).

Mar_Mar schrieb:

As I wrote in my initial post, a prefabricated house is out for us. We have thought long and hard and will definitely build with solid construction. Whether that will be a prefabricated solid construction or traditional masonry is still to be decided, but it won’t be a timber frame. We are currently in a thread about the building material expanded clay aggregate, not about the advantages of prefab houses.

Where did I miss why timber frame houses are absolutely out of the question for you? By the way, this would be the wrong forum for anyone who would strictly stick to the question without the slightest broader perspective. Here, people usually consider “the whole picture.” That might be because of the experienced discussants who often already own a (not always first) home. Making people run into walls armed with open knives is something that only cynics could probably be expected to do. ;-)

Now about the post #17 of mine I haven’t addressed yet:

Mar_Mar schrieb:

Shell construction... um, well, I’ll step back on that one. [...]
“If the planner is clever, the best possible profile uniformity should be achievable even under these circumstances” — sorry, I don’t understand the sentence or the word “plietsch” :/
We have DIY plans, of course we think about how it might look. We now have professional plans from companies that we don’t like so much (HTR on the ground floor) and our own ideas. I’m happy to share them 🙂
“Oh, twelve meters, and yet the neighbor builds shorter??”
What do you mean by that? Is that irony?

With the suggestion “shell construction,” I wanted to point out the possibility to use the same “shell builder” as the semi-detached neighbor even if you want to hire different contractors for the finishing trades and/or choose a significantly higher standard. Doing work yourself is not necessarily required. “Plietsch” means something like “smart guy,” as in “clever, a bright fellow.” And such a person could definitely manage to align the rooflines quite closely even with different house depths. And no, I’m honestly surprised that with only twelve meters (about 39 feet) you are still building deeper than the semi-detached neighbors. Yes, please share the plans — including those you consider imperfect. We can rearrange them here (not me personally, I’m not great at drawing, but people like Katja, Yvonne, RomeoZwo, and others usually do that here, as you may have noticed).

Mar_Mar schrieb:

Can anyone say something about the disadvantages of prefabricated expanded clay aggregate components? Looking at the values, one should consider possibly using a 42cm (17 inches) thick wall if building monolithically.

Basically, the “ingredients” are the same, although the wall panels are produced differently (laid horizontally, which you can see in the video on Lechner Massivhaus’s site) resulting in an even smoother interior wall surface compared to the plan bricks. So technically the “same material,” but “ready for wallpaper.” I’m personally living in a house made of 30cm (12 inches) porous concrete blocks and don’t think a 24cm (9.5 inches) porous brick wall would be equivalent. On the idea of building with wall panels, I’ll quote myself from another thread: wall panels “in quantities the size of half a semi-detached house are pretty much a joke, at least just over the line of practical use.”

Mar_Mar schrieb:

Another general question: All solid masonry house providers insist on installing mechanical ventilation (they say it’s required), but Lech*** with expanded clay aggregate does not, although it is just as airtight. Why is that? Don’t the same rules apply to everyone?

The rules are the same, and as far as I know, mechanical ventilation is still optional for everyone. Most likely, Lechner Massivhaus (are you actually planning to build with KlimaPOR? KlimaVER would not be expanded clay aggregate but another option from them) simply does not integrate mechanical ventilation into their system (CoreHaus as well, they then recommend decentralized mechanical ventilation instead). By the way, on Lechner Massivhaus’s site you can also see a project called “Living at Sonnenwald” with semi-detached houses that are described as having “solid walls,” but in the floor plans are shown as “two-layered” with external insulation systems (ETICS/WDVS).

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Nida35a schrieb:

We have 42cm (17 inches) solid masonry walls, @motorradsilke has 36.5cm (14.5 inches), and both of us live comfortably in our houses,

And with low heating costs despite only 36cm (14 inches) wall thickness. So far (moved in October 2021) there have been no cracks at all. And although the house was built without a ventilation system, the indoor humidity levels are perfect, between 40 and 60%, with no mold forming anywhere. And no, we don’t ventilate 12 times a day; 2 to 3 times is more than enough. Our house is designed so that air can circulate freely in all directions. Plus, the front door is opened several times a day anyway.

We are building in the Eifel region, and our structural builder wants to use pumice stone. However, we don’t know anyone with experience and are also unfamiliar with the terms HW2 and 010. The exterior walls are planned to be 36.5 cm (14 inches) thick, and the interior walls 24 cm (9.5 inches). Can anyone provide information or has experience building with pumice stone?

We would be very grateful for any insights.

Bobby007 schrieb:

The exterior walls are planned to be 36.5cm (14.4 inches) thick, with an interior thickness of 24cm (9.4 inches). Can anyone share their experience with this, or have built using pumice blocks themselves?

My previous owner built the house in the mid-1960s.

Bobby007 schrieb:

Designation HW2, 010

These are likely HW-plan solid blocks with a strength class of 2 and a thermal conductivity of 0.10 W/mK, meaning they provide very good insulation.

Something like this:

Bobby007 schrieb:

We are building in the Eifel region, and our shell contractor would like to use pumice stone for construction. However, we don't know anyone with experience in this [...] Can anyone share information or maybe has built with pumice themselves?

Are you newcomers? The locals in the Eifel and Pellenz regions, extending to the Neuwied Basin, have preferred this traditional local building material for centuries. I myself live in a monolithic pumice house, with walls 30 cm (12 inches) thick due to the building period. From a resident’s or user’s perspective, I don’t know of any significant differences compared to lightweight expanded clay aggregate (LECA). Microscopically ;-) there are differences, but you won’t notice them in everyday use. You would be wise to follow the shell contractor’s recommendation (see "11ant Steinemantra").

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