The U-value of aerated concrete

Aerated concrete has excellent thermal insulation properties. However, as it is precisely the U-values ​​of aerated concrete ordered, and thus the thermal insulation of aerated concrete can be affected, this article informs.

Different values

The U-values ​​of aerated concrete blocks are not always the same. They may vary depending on grade and manufacturer.

Overall, however, aerated concrete is the building material with the highest thermal insulation values ​​that are possible. As a result, additional external insulation can also be dispensed with on exterior walls made of aerated concrete blocks. Nevertheless, the values ​​given by the EnEV are far exceeded in any case.

The U-value of aerated concrete: U-value

Typically, the U-values ​​for Ytong's "Thermoblock" products are between 0.29 and 0.17. It is measured unpowdered. The EnEV, on the other hand, requires a value of 0.28 (exterior wall to air) or 0.50 (exterior wall to earth) for living spaces. By comparison, a brick wall would require around 13 cm of PUR insulation.

The Duisburg-based manufacturer Xella, on the other hand, offers counters whose heat transfer value is even lower. With an outer wall thickness of 36.5 cm, a U-value of 0.18 is achieved, with 48 cm wall thickness even reaches a value of 0.14. This is sufficient even for passive house standard.

Measures to reduce the heat transfer

A major problem with masonry are the joints. Autoclaved aerated concrete blocks are as good as always designed as plan stones, thus the bearing joint is already very small.

Additionally you can use thermal mortar here. As a result, the heat transfer through the joint is further reduced, the entire U-value of the component thus decreases once again.

Larger stones to use is usually quite unproblematic due to the low weight of aerated concrete blocks. The larger the stone surface, the lower the heat transfer. This can also be a measure to increase the thermal insulation of a component yet.

The impact of the stone size can already be taken into account in the planning, and the U-value can be estimated accordingly well in advance.

An increase in the wall thickness naturally also lowers the U-value of an outer wall.

Tips & Tricks

High thermal insulation tiles do not necessarily have to be more expensive. Depending on the manufacturer, different insulation classes are often offered at only slightly different prices.

Video Board: Autoclaved Aerated Concrete - Block Installation - Part 1