ᐅ Is the architect's cost estimate realistic?

DaGoodness schrieb:

Is there a detailed cost breakdown from the architect showing the individual amounts listed above, or did he just randomly assign five figures and present them to you?
Without further information, the numbers are meaningless.
There must be a reason why his estimate is so far above the average.

Otherwise, I agree with nordanney... with certain specifications, costs can quickly reach such levels.

Sure, with the right specifications, but these were neither requested nor communicated.
The requirement was KFW 55, standard features, no extras like smart home systems, aluminum windows, special flooring, etc.

No, the costs are not broken down. It is only a rough cost estimate.
The gross floor area (GFA) is given as 260 m2 (2800 sq ft) and the gross volume (GV) as 910 m3 (32,100 cu ft).
The costs around 700 are itemized, but I don’t think that really helps, does it?

7.1	Phases 1-4	12,000
7.2	Phases 5-9	50,000
7.3	Surveying	1,600
7.4	Structural planning	7,000
7.5	Structural calculation review	3,000
7.6	Soil investigation report	2,500
7.7	Specialist planning	-
7.8	Energy consultant	2,000
7.9	Safety coordinator	-
7.10	Building permit / planning permission	3,000

PascalBW schrieb:

No, the costs are not broken down. It is only a rough cost estimate.
The gross floor area (GFA) is given as 260 m2 (2800 sq ft) and the gross volume (GV) as 910 m3 (32,140 cu ft)

How do you get 910 cubic meters (32,140 cu ft) for 125 m2 (1345 sq ft) of living space? That would be a rectangular prism of 10 x 10 x 9 meters (33 x 33 x 30 feet).
Or with 260 m2 (2800 sq ft) GFA = 125 m2 (1345 sq ft) living space.
==> There is a huge error in your numbers, probably in the living space.

For comparison: my two-family house (without the extension) actually has 910 m3 (32,140 cu ft) volume (no joke!) but 160 m2 (1720 sq ft) of living space plus about 25–30 m2 (270–320 sq ft) of hallway/staircase areas.

P.S. In a single-family house, the living space is on average about 70–75% of the GFA.

Yes, that is probably true. However, it seems more like a mistake by the architect if I say I want 125 sqm (1350 sq ft) of living space and receive an offer in the range of 180–200 sqm (1937–2153 sq ft), right?
Due to the adjacent building, the structure must have a very high and steep roof. However, the roof is not intended to be converted into living space.
I am assuming 3 full floors plus the roof.
Then I should have about 55–60 sqm (592–645 sq ft) of floor area per floor. That would mean roughly a 10x6 m (33x20 ft) footprint.
That would result in a gross floor area (GFA) of 165–180 sqm (1776–1937 sq ft).
And from that, about 70–75% would be usable living space to reach 125 sqm (1350 sq ft) of living area, right?

PascalBW schrieb:

Yes, that’s probably true. But wouldn’t it be more of an architect’s mistake if I say I want 125 sqm (1350 sq ft) of living space and receive an offer for something between 180 - 200 sqm (1937 - 2153 sq ft), right?
The building must have a very high and steep roof because of the adjoining structure. However, the roof is not intended to be developed into additional living space.
I’m assuming 3 full floors plus the roof.
Then each floor should have around 55-60 sqm (592 - 645 sq ft) of floor area. That would be roughly a 10x6 m (33x20 ft) footprint.
That would result in a gross floor area of about 165-180 sqm (1776 - 1937 sq ft).
And then 70-75% of that would be living space to reach 125 sqm (1350 sq ft), correct?

Yep. Sounds about right.

Is there no detailed house plan or floor/volume calculation yet from which these numbers can be verified?

No, unfortunately, there isn’t one.

I used the BKI planning tool with the construction cost index from 01/2024 (163.3). According to the table, the architect calculates €1500 for the 300 category and €388 for the 400 category.

In the BKI planning tool, which the architect also uses, the regional factor for the 300 category costs ranges from €1065 to €1343. For the 400 category, the range is €205 to €345.

I took the highest values in each case. This results in the following amounts for a gross floor area (GFA) of 260:

€1343 * 260 = €349,180
€345 * 260 = €89,700

So, the total for 300/400 is €438,880. That aligns more closely with what I calculated...

But as you already said, one is an estimate, the other is real life.

Of course, the gross floor area (GFA) still does not meet our requirements or expectations, as it remains too large and unchanged.