Is it sensible to build a new semi-detached house without the KfW standard?

The 17.5cm Poroton also seemed quite small to me. In other houses, I have more often seen 24cm Poroton + 16cm ETICS. 17.5cm were then for load-bearing interior walls. 11cm for non-load-bearing ones.

I don't understand the ETICS with Poroton anyway... If I use 0.8 36.5cm bricks there, I don't need ETICS.

I am completely undecided about the property. Location, layout, etc. are great. But almost €370,000 for a 125m² semi-detached house is a statement.

Well, it depends on the location. In some areas, it can also be a bargain.

I don't get the WDVS with Poroton anyway... If I use 0.8 36.5 cm bricks, I don't need WDVS. Well, it depends on the location. In some areas, it can also be a bargain.

The land prices are at 200€/m². For 300m², I would therefore subtract about 65,000€ in additional purchase costs. That leaves a good 300,000€ for the bare semi-detached house.

Why actually a semi-detached house? Is there a special reason for that? Personally, I wouldn't take the house at that price based on the insulation values.

The land prices are at €200/m². For 300m² I would therefore deduct about €65,000 in ancillary purchase costs.

That may theoretically be the case. But, hand on heart – are there really such plots available on the open market, in the location, size and at the price you demand?

Or are these perhaps just leftover parcels in the existing stock that are passed from hand to hand? Or does the price refer more to the land value than to the actual amount paid?
But if it really were that simple then just buy one for €60,000, plain and simple.

That leaves a good €300,000 for the bare semi-detached house.

125m² are also €250,000, without paint and flooring. Plus at least €30,000 in construction ancillary costs and a bit for the outdoor area – and your acquisition costs quickly amount to around €300,000 as well. THAT is the reality! You could then at least decide on the floor plan and the type of masonry yourself.

200€/m² apply developed for plots (completely new development area) that were sold last year. I would preferably like to build a single-family house but it may still take a while until a plot is available (I am on the municipality's waiting list). However, I could also live well with a semi-detached house. I do not doubt that the seller of the house can ask for more because plots are relatively scarce.

Recently, 3km away, there was a KfW55 semi-detached house, 162m², including paving work, garage with electric gate, finished attic with underfloor heating for 380,000€. Unfortunately, I missed it. Therefore, the house appears quite expensive in comparison and without all the extra features around it. The question of whether the price for this house is reasonable still has to be asked. A relatively low energy standard does not improve it.

Hence my question: Are KfW 100 / Energy Saving Ordinance 2016 houses still state of the art today or should one only buy KfW70 or smaller?

Even if the market may justify the price, my decision in doubt would be not to buy and continue renting. Better than tying yourself to an overpriced property.

It would not be mine. As thin as the brick, as thick the Styrofoam. Algae growth is inevitable.