Calculated construction costs incomprehensibly high

Maybe someone of you can tell me something about this. Planned is a 2-story house with 153 sqm of living space without a basement, flat roof, brick facing. Building volume about 900 cbm. A garage 3.5 x 6 m, which will be attached to the house made of exposed concrete, and a shed on the other side with wooden cladding (3x5m). Gas heating with solar thermal energy, controlled residential ventilation, underfloor heating. Windows are to be darkened with venetian blinds. An installed fireplace. Plot is available. Should, if possible, achieve KFW 55.
I have planned €350k for the construction, the builder’s invoice amounts to €412k, and in the invoice he did not even list solar thermal energy and fireplace. According to his invoice, the house only reaches KFW 70.

Unfortunately, you did not say where in NRW you want to build; there are significant price differences!

To give you an overview, I assume the Düsseldorf/Cologne region.

[*]Cuboid with flat roof on slab according to Energy Saving Ordinance about €230k
[*]Brick facing about €20k
[*]Extra cost masonry/insulation KfW 55 about €8k
[*]The solar system about €4k

# must be calculated precisely whether these measures combined with gas + solar are sufficient to achieve KfW 55!

[*]Masonry garage about €18k
[*]Carport about €7k
[*]Controlled residential ventilation with heat recovery about €10k
[*]Venetian blinds for 12 windows, all floor-to-ceiling (2.635 x 2.135 m) about €14.5k
[*]plus wind monitor €5k
[*]Chimney draft about €4.5k
[*]Fireplace starting at €8k
[*]Painting/flooring in EL €20k
[*]Outdoor facilities in EL €10k (only the essentials)
[*]Additional construction costs €30k
[*]Reserve for extras €10k

I come to about €399k if you would award to a general contractor. Therefore, and also because the individual trade prices seem somewhat mixed to me, the forecast construction cost of your architect is not so far off and by no means luxurious, but a good average.

Rhenish regards

Electrical: 8,000
Sanitary: 10,000
Ventilation: 9,000
Windows: 16,000
Garage door+door: 5,500

Regarding the items, I can say a little based on my current experience:

Electrical – we won’t get by with double that amount. I would describe our electrical equipment as good, but not excessive. No bus system.

Sanitary – 10,000 is just the surcharge for the master bathroom compared to the standard from the offer. Unfortunately, there are two more bathrooms and a guest WC.

Ventilation – also set rather on the low end; depending on which main unit we choose, we come out between 10,500 and 13,000 EUR, but we have connected a bit more area.

Windows – depending on color preference or security features, this can quickly become more expensive.

Garage door and door – seems very expensive to me. For comparison: we get two insulated sectional doors in the desired color with door drive and an additional remote control each, including installation, for 3,300-3,400 EUR (depending on whether we choose novoferm or Hörmann). Of course, if the door is a highly secure secondary entrance door to the house, that relativizes your price.

A general contractor or authorized construction manager will not disclose prices for individual trades; why would they?

Back then we obtained various offers, only one broke down the prices that way. Why is that interesting for builders? Cost transparency! To be able to decide whether to take on certain things themselves or assign them elsewhere. This provider would have participated as well. The others would not, accordingly showing a lot of pages of text and a large sum at the bottom right. Interesting at that point: this provider would have credited EUR 11,000 if the tile trade was removed, whereas the one who broke down prices individually priced the trade at EUR 16,500 (same quantities/measures/tiles). At that point, the differing interests of general contractor and builder simply clash.

Sanitary - 10,000 is the additional cost for the main bathroom compared to the standard in the offer. Unfortunately, there are still two more bathrooms and one guest WC. 10,500 and 13,000 gone, but they have a bit more area connected.

.

What made your bathroom so expensive?

Best regards
Sabine

Shower channel instead of "normal drain"; corner bathtub instead of Kaldewei 0815 hardware store model, the shower enclosures made of glass, electric towel radiator, 100 cm washbasin with drawers underneath instead of a normal 60 cm semi-circular sink, the thermostatic fittings, the faucet... rimless toilet. That quickly burns through one or the other thousand...

Yes, that really adds up. How much should you expect to pay for a 1m wide washbasin with a cabinet underneath? I haven’t dealt with that at all yet.

Best regards
Sabine

For the combination of washbasin, base cabinet, mirror cabinet, and faucet, I would estimate 1,500 to 2,000 euros if you buy it cheaply online and install it yourself. With us, the guest WC and main bathroom together cost an additional 20k compared to the standard. Washbasins are among the most expensive, and there they are only considered in terms of material. Also expensive are concealed faucets, shower enclosures, and designer bathroom radiators. We now have the glassworker do the shower enclosures, which costs only half.