ᐅ Masonry for a Two-Family House

Hello,

we are a bit overwhelmed when it comes to choosing the exterior masonry.

Basically, the choice is between Poroton (better sound insulation, absorbs less moisture) or aerated concrete (better thermal insulation).

What do you think about these options? It’s for a two-family house with 220 sqm (2,370 sq ft).

1. Poroton T 14 24 cm (9.5 inches) + ETICS with 12 cm (5 inches) rigid foam board, thermal conductivity 0.035 W/(m·K)
2. Poroton 36.5 cm (14 inches) without insulation, T 10, U-value 0.25
3. 24 cm (9.5 inches) aerated concrete without insulation (not really an option, right?)
4. 30 cm (12 inches) aerated concrete + €7,500
5. 36.5 cm (14 inches) aerated concrete + €12,000
6.

What makes sense?
Of course, an ETICS is cheaper than a monolithic wall construction.

Matter of preference: in my opinion, none of those—go for sand-lime brick plus external thermal insulation composite system (ETICS). Best soundproofing, best structural stability, best thermal insulation combined. Alternatively, a double-shell wall.

By the way, aerated concrete was the cheapest option for us (but definitely not an option in our case), prices vary significantly depending on the region.

Build with the system your construction company knows best. When done properly, all systems are well suited for single-family homes, and you won’t notice any difference living there.

fortuneflake schrieb:
3. 24 cm (9.5 inches) aerated concrete without insulation (that’s not really an option, right?)

I also find it hard to imagine that this is still being offered.

fortuneflake schrieb:
4. 30 cm (12 inches) aerated concrete + €7,500
5. 36.5 cm (14.4 inches) aerated concrete + €12,000

Both options seem reasonable to me: number 4 for the energy-saving regulation, and number 5 for KfW55 standard. However, as I have recommended several times already,

Tego12 schrieb:
Build with the system your contractor knows best. When properly executed, all systems are well suited for single-family homes, and you won’t notice any difference living there.

the most sensible advice would almost be to consider finding another builder if all the mentioned alternatives come from the same company.

If someone says, use block X alone for the energy-saving regulation or with enhancements for KfW, that’s fine; but knowing block X and block Y equally well—that I question. I would believe that someone handles Bisotherm just as well and gladly as KLB. But Ytong and Poroton are too different from each other.

Typically, a builder either belongs to the “red brick” or “white block” camp; a mix of both, like a hybrid approach, is rare.

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Basically, as the client, I have the choice. All companies would therefore use both types of blocks.

The question is basically whether to use poroton or aerated concrete. Most companies we visited prefer poroton because the sound insulation with aerated concrete is considered insufficient.

Regarding point 1: The company explained to us that using an exterior insulation system (ETICS) is more cost-effective, partly due to a smaller foundation slab. They prefer to build with this system. But how is the sound insulation with a 24 cm (9.5 inch) block? There is a road nearby.

Regarding point 2: Two companies build exclusively with monolithic walls, but these companies also have a higher base price.

Regarding point 3: Franchise companies claim that a 24 cm (9.5 inch) wall without insulation is sufficient, but includes decentralized ventilation. The thicker walls have the price increases mentioned here.

fortuneflake schrieb:
Regarding point 1. The company told us that using ETICS would be cheaper because, among other things, it allows for a smaller foundation slab.

The joke that the house could become significantly cheaper due to a foundation slab that is 32 cm (13 inches) shorter and narrower is a good one. I should frame that.

fortuneflake schrieb:
But how is the sound insulation with a 24 cm (9.5 inch) brick? There is a road nearby for us.

When it comes to sound insulation, you shouldn't imagine a wall as a heavily armored crocodile that completely blocks sound—it’s not that simple. Any newly built house initially experiences more noise, but this is not due to the supposedly bad aerated concrete; rather, it is simply because there is initially no vegetation to scatter the sound as it travels from the street to the house wall.

fortuneflake schrieb:
Regarding point 3. Franchise company - claims 24 cm (9.5 inch) wall without insulation is sufficient, with decentralized ventilation included.

A franchise of whom or what? I haven’t come across 24 cm (9.5 inch) exterior walls in new builds since the oil crisis of 1973. If that really works, they should patent it. What kind of magic additive is supposed to be in their brick?

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Changing from T14 to T9 would cost about €12,000 with the general contractor we are currently favoring. This contractor primarily builds with ETICS (External Thermal Insulation Composite Systems).

Would you spend that money?

The two general contractors who build with T9 have accordingly higher prices from the start.

The other option would be to "upgrade" the Town & Country wall for an additional cost, probably to 36.5cm (14.4 inches) aerated concrete.