Material exterior walls and interior walls (KfW 55 standard)

Dear all,

after the initial talks with regional general contractors and reading construction specifications, questions arose regarding the wall material (structure).

We would (since it obviously doesn’t deviate much from the standard) like to build KfW-55. Furthermore, we want good sound insulation (unfortunately, the air traffic of BER cannot be completely ignored in the east of Berlin, even if the planes will not fly directly over us). Therefore, I am still a bit overwhelmed by the many exterior wall options.

In principle, monolithic seems advantageous to me, as stones should significantly outlast an ETICS and are easier to maintain? Are there already reliable experiences regarding ETICS? Also, I am somewhat uncertain about calcium silicate bricks (best sound insulation, but I don’t want sand to keep trickling when drilling?!). How is the renewal of plaster on the facade? I can at least not recall this being done at my parents’ house in nearly 30 years (house from the late 70s).

From a wall thickness of 36.5 cm, aerated concrete should meet the KfW standard requirements (U-value <0.2), while Poroton requires additional filling with perlite. However, the sound insulation of Poroton is better than that of aerated concrete, if I have researched correctly (at least on paper). How does this behave in practice?

Lightweight expanded clay aggregate was also offered to us (however, as a finished system wall). But then you would have to add a lot of ETICS to reach the KfW standard (and how is the sound insulation here)?

And above all: What do the options cost (calcium silicate + ETICS vs aerated concrete vs insulated Poroton) for, e.g., a city villa with a 10x10 m floor plan? Most general contractors only build with one or the other (although I have not found insulated Poroton yet?!).

To avoid excessive sound transmission inside the house as well, normal Poroton walls seemed sensible to me (12 or 24 cm if load-bearing)? Calcium silicate might be somewhat heavy (and the sand issue)?

Many thanks for your opinions
Stephan

P.S.: Are we really looking at 2100-2500 €/sqm for a "normal standard" house now also in Brandenburg? Or did we approach the wrong general contractors?

Are we really at "normal standard" houses now also in Brandenburg at 2100-2500€/sqm?

If you don't want a standard off-the-shelf house or price list, but your ideas make your house, this is how you should calculate.
Our general contractor built with filled 42cm Poroton bricks, interior walls 11cm KS.
Since Tegel is closed, you also still have our planes on your back :cool:

but I don’t want to constantly have sand trickling down when drilling?!

How do you come to think that sand would trickle down with KS? Consider my stone mantra and build with the contractor with whom you have the best feeling, and then with a stone that they often process.

If you don't want a standard house off the shelf or from a price list, but your ideas should shape your house, it should be calculated like this. Our general contractor built with filled 42cm Poroton bricks, interior walls 11cm KS. Since Tegel is closed, you still have our planes on your tail :cool:

I just checked their homepage. It says the building material is Liaplan (that is expanded clay). Could that be true or did you specifically ask for Poroton?

Yeah.. be glad, where we live right now we can wave at the planes. I definitely need to change that again, even though it's nice with the lakes ;-).

but I don’t want to have sand trickling down constantly while drilling?!)

Drilling dust always trickles, no matter what kind of stone or wood is used.

How does it hold up with the renewal of plaster on the facade?

You don’t need to... I had a plastered house from 1978... small settlement cracks or cracks in the paint can be “repaired” differently. The plaster will probably outlast you.

From 36.5 cm wall thickness, aerated concrete should meet the requirements of the KfW standard (U-value <0.2), while Poroton needs additional filling with perlite.

Sound insulation or not: most of the noise comes through the windows anyway.

P.S.: Are we really at 2100-2500 €/sqm now for "normal standard" houses in Brandenburg? Or did we have the wrong general contractors?

It feels about right to me. But ask , he also wants to build in Brandenburg and knows the prices.

P.S.: Are we really at "normal standard" houses now also in Brandenburg at 2100-2500€/sqm? Or did we deal with the wrong GCs?

That should be about right. We pay (old price) about €2,800, but including: - KFW 55 - Ground-source heat pump, controlled residential ventilation - Photovoltaic system 13.29 kWp - raised ceilings (3m raw height) - rain cistern (10sqm) - bungalow 140-150sqm - fireplace - electric shutters including central control - windows laminated on both sides. Color: Winchester.

If you need recommendations for construction companies, let me know.