Insulate old building with 38 cm bricks using aerated concrete / Ytong

Hello,

As mentioned at the beginning of the question, I am considering buying a house. According to an unreadable floor plan, a 34cm brick was used (does that even exist? Maybe it’s actually 38cm). I would like to insulate the house in the future and want to inform myself in advance about the options available. For several reasons, I am against insulation with Styrofoam! Now I am looking for a good alternative! In this context, I came across aerated concrete/autoclaved aerated concrete/mineral foam/Ytong/and whatever else it is called! Can these blocks be placed as insulation on/in front of the bricks? Does anyone have experience with this? Moisture/mold? Problems?

Thank you very much and best regards!

. According to an illegible floor plan, a 34cm brick was installed (does that even exist?

In the floor plan, the total thickness of the wall is probably indicated, with or without plaster. 34 cm solid brick in old buildings is rather rare. Does the house have a clinker facade?

I would like to insulate the house in the future and inform myself in advance about the options available

With the building’s year of construction, one could make an estimate about what it actually is and whether insulation is even necessary or sensible.

Insulation options:

For cavity walls with an air gap: blowing in with suitable insulation material
Otherwise: ETICS made of EPS (Styrofoam) or based on natural insulation materials such as wood fiber or jute with a plaster layer
or insulation of the exterior wall with flexible insulation mats between wooden battens or other supports and weather protection with a ventilated wooden rain screen facade or facade panels

Can these bricks be placed as insulation in front of/on the bricks?

Theoretically, it can be done, but it is difficult and hardly anyone does it because it has many disadvantages. You need an additional foundation around the house. As a result, all connections may need to be renewed. Moreover, the whole thing must be applied to the exterior wall without an air layer, which is more difficult with masonry than with individual insulation boards. If it is to be mineral, a large aerated concrete block manufacturer also offers a fully mineral ETICS based on lime, sand, and cement.

In general, one should first look at what has been installed so far, what the U-value and properties are, and what other weak points the building has – in many cases, exterior walls are not the most important focus; rather, there are usually simpler and cheaper ways to save energy.

Addendum: I just saw that the house was built in 1965. In which federal state is "OE," in other words, where is the house located? What does it look like? (Plaster, clinker, other facade?) Based on the year of construction, with single-layer construction, usually pumice hollow blocks (southern Germany) or hollow blocks made of brick splinters or also lattice bricks would be used. Normally, though, more likely in a thickness of 30 cm. For a clinker facade, I would guess a 24 cm load-bearing wall made of hollow blocks + 11.5 cm clinker without an air layer. Air layers between the load-bearing wall and the facing wall were rare in the 1960s.

Thanks first of all for your answer, the "fully mineral-based ETICS based on lime, sand and cement" is what I was looking for and "OE" stands for Austria, unfortunately I don't have more details about the facade, I can exclude clinker, it looks like a 38 brick and plaster to me

"OE" stands for Austria, unfortunately I don't have more details about the facade, I can rule out clinker, to me it looks like a 38 brick and plaster

Oh - with "AT" I would have thought more along those lines. Clinker in Austria is probably rather rare and I am not familiar with the building typology in Austria either. 38cm lattice bricks, pumice stones, old aerated concrete or hollow blocks, whatever was used, would have a U-value between 0.6 and 1.0 W/m²K. Personally, with that wall thickness and U-value, I would not additionally insulate the outside, but rather eliminate other weak points. At most, insulate the north side if there are few windows there.

So far, no plan has been too illegible for me. So feel free to upload it or send it to me via PM.

In Germany, the old "Reich format" was still in use up until the post-war years, which would have allowed for 38 cm (exactly one and a half bricks, that is one brick plus a half). It is possible that Austria switched over later or still had leftover stock at that time.

However, at that time, these were typically full bricks in the normal format. This may explain the wall thickness, which in particular seems to have been somewhat more generously dimensioned in the Alpine federal states.

24 cm would also be conceivable (one brick in the current format system), and then possibly already as a large block, provided it is made from lighter stone (pumice / tuff).

Whether and what kind of insulation is applied inside or outside would require us to know the building better (photos help).

"OE" is probably automatically assigned by the forum software when you specify Austria as the country of residence.