ᐅ Exterior wall constructed monolithically with lightweight concrete (e.g., expanded clay aggregate)

Hello,

after a longer selection process, we have decided to build our new single-family house with Liapor, using monolithic exterior walls (no ETICS / external thermal insulation composite system). Currently, we are considering bricks, aerated concrete (Ytong), and lightweight concrete system elements (Liapor) in the final round.

A question regarding lightweight concrete: so far, we only find quite good evaluations concerning indoor climate, but actually, all suppliers who build with Liapor system elements use ETICS. This makes us a bit uncertain. Based purely on the figures (thermal conductivity, U-value, sound insulation, heat storage capacity, etc.), a wall made of lightweight concrete is on the same level as bricks or Ytong.

Is there any reason why lightweight concrete might not be suitable for monolithic construction? Are the joints of the wall elements perhaps the problem? If monolithic walls with lightweight concrete system elements are already a common practice (and we may not have researched thoroughly enough), does anyone here have experience with this?

Many thanks in advance for any helpful advice.

Titus

I can’t answer your questions directly. But have you considered pumice stone? We build monolithically with pumice – it has similar qualities to Poroton and aerated concrete. Also, I personally feel better using a "natural stone"... (volcanic stone).

Hello,

ClaasCPunkt schrieb:
...We are building monolithically with pumice – it has similar properties to Poroton and aerated concrete.

Incorrect! The pumice stone does not have just "similar" values to aerated concrete or hollow bricks, but actually better ones.

The lighter the pumice material used, the better the thermal insulation. The key figure for this is the so-called thermal conductivity λ (lambda). This indicates the conductivity of a material in the unit W/(mK); the lower the value, the poorer the heat conduction and the better the insulation. While traditional pumice stones reach λ = 0.18 W/(mK), through...

• selected pumice qualities and
• special arrangements of the air chambers within the stones

...so-called thermopumice stones achieve λ-values of 0.11 W/(mK) or better.

Source: our homepage

Best regards

Titus schrieb:
(...) Question about lightweight concrete: (...) actually, all the suppliers that build with Liapor system elements use external thermal insulation composite systems (ETICS). This makes us a bit uncertain. Based purely on the numbers (thermal conductivity, U-value, sound insulation, thermal storage capacity, etc.), a lightweight concrete wall is comparable to brick or aerated concrete (Ytong). Is there any reason why lightweight concrete is not suitable for monolithic construction? Are the joints between the wall elements the problem? If monolithic construction using lightweight concrete system elements is already common practice (and we just haven’t researched properly), does anyone here have experience with it? Many thanks in advance for any helpful insights Titus

Hello Titus,

Unfortunately, I have no personal experience but have spoken with two home builders who like to use Liapor system elements:

Liapor is a lightweight concrete, not aerated concrete. According to the product specifications (just looked it up), the Liapor solid wall achieves thermal conductivity values between 0.13 - 0.18 W/mK. With a wall thickness of 36.5 cm (14 inches), that corresponds to U-values between 0.36 and 0.49 W/m²K.

Conclusion: The Liapor solid wall cannot be used without additional insulation.

So: either an ETICS is applied on the outside, or Liapor system elements with an attached ETICS (Liaver layer). But even then, the U-values are not very impressive.

For this reason, I gave up on this idea and am currently considering bricks, even though that’s not the cheapest option...

Best regards
Olaf

Well, I should also say something here.

There is indeed a manufacturer that produces monolithic and open-porous Liapor solid walls. These are made in thicknesses of 42.5 and 49.5 cm (17 and 19.5 inches), carry the quality seal of the IBR (Institute for Building Biology in Rosenheim), labeled “Building Biology Tested and Recommended,” and comply with KfW55 standards according to the 2016 Energy Saving Ordinance without requiring any additional polystyrene insulation on the facade.

Have a great weekend!
Hans-Jürgen

We built using 42.5 monolithic construction according to KfW 70 standards and are still very satisfied after one year (thermal insulation – as far as can be judged from the heat pump’s electricity consumption so far, soundproofing, etc.).