ᐅ Masonry – Construction Method for a Custom-Designed Single-Family Home

Dear community,

I am new here and would like to gather your expert opinions and experiences on a specific topic. We are planning to build a custom-designed single-family house in the Bauhaus style and are currently deciding between two general contractors using different construction methods:

• Option 1: Load-bearing masonry wall made of 17.5 cm (7 inches) aerated concrete, supplemented with mineral fiber insulation, a ventilation gap, and a facing brick veneer.
• Option 2: Monolithic construction with 36.5 cm (14 inches) aerated concrete PPW2, also with a brick facade.

One general contractor claims that an exterior wall with only 17.5 cm (7 inches) aerated concrete is structurally questionable—especially for a two-story building with two reinforced concrete floors. A building expert we consulted disagrees with this and explains that the structural design is perfectly sound if calculated correctly.

Now my question to the experts and experienced homeowners in this forum:
Has anyone had experience with either of these construction methods? How do you assess the general contractor’s argument regarding load-bearing capacity and long-term stability? What aspects would you consider most important when making this decision?

I look forward to your opinions and feedback!

Best regards

The general contractor’s statement is nonsense. If the structural engineer says it’s fine, then it’s fine.

I also chose a monolithic construction method. I find it more appealing, plus I don’t need plastic on the walls.

Funny, by the way... Take a look at an aerated concrete block like PPW2. You can drive in a 14mm (9/16 inch) TOX anchor without pre-drilling because these blocks are so “soft.” And a 14mm (9/16 inch) anchor with a 10mm (3/8 inch) Spax screw holds about 40–50 kg (88–110 lbs) in PPW2.
I would have more doubts about the load-bearing capacity here than with Poroton 17.5.
I think you can only build up to 2 full stories with PPW2... or was it 3?

I actually built with 36.5cm (14 inch) PPW2 blocks and I’m satisfied. The kitchen cabinets on the exterior walls are held by four 14mm (9/16 inch) anchors with 10mm (3/8 inch) Spax screws each. The interior walls made of PPW4 carry significantly more because they are “denser.”

GU2’s statement is nonsense. First of all, there are blocks with higher compressive strength, so aerated concrete is not just aerated concrete. Secondly, the building expert is, of course, correct. These things are calculated anyway.
However, I would still prefer calcium silicate blocks. First, they are even stronger; second, they provide more mass, which also improves sound insulation.
But it could mean that the insulation might need to be a bit thicker, making the overall cost higher.
In my personal preference, the ranking would be:
1. Cavity wall
2. Monolithic construction
3. External thermal insulation composite system (ETICS) or timber frame construction

With autoclaved aerated concrete (AAC) in monolithic construction, the situation is actually the opposite. The exterior walls and AAC blocks are designed at the lower limit to improve insulation properties. The more air content inside the block, the better the insulation, but this reduces compressive strength.

Keep in mind that mounting a heavy awning or canopy on AAC blocks… I wouldn’t recommend it. Of course, the same applies to external thermal insulation composite systems (ETICS), as they won’t hold either.

Yes, that's correct, but the skepticism regarding the structural stability was about a double-shell wall. That's why I think that if the structure were to be borderline in terms of stability, a denser block would probably be used. The insulation is then placed in the cavity. However, my recommendation was still to opt for insulated masonry units (KSS).

I agree with 11ant and would go with what is common in the region and well known by the structural builders.

Calcium silicate bricks are quite heavy, which will probably increase the cost of the foundation. Also, whether sound insulation is necessary depends on the situation. I don’t think it is, unless you live near a main road.