Costs according to "converted room"

Hello,

after we have now said goodbye to our prefab house provider, we have visited various solid construction companies in the last few weeks who also offer turnkey solutions. However, we also visited a company that would only build the shell; all other trades would have to be contracted by ourselves.

This provider also gave us a calculation for the costs of the entire house based on the volume of enclosed space (according to DIN 277).

He calculated €300 per m³ of enclosed space for the house (KFW 70) and €145 per m³ for the garage.

Of course, this can only be a rough guideline and depends on which heating system we want, etc... But can you really calculate with these figures?

Hello,

... and garage 140m³.

If your architect wants to calculate the cost of a masonry garage with this, he is, in my opinion, mistaken. Realistically, it is €200/m³.

Kind regards

Hello,


If your architect wants to calculate the costs of a masonry garage with that, in my opinion he is mistaken. Realistic is €200/m³.

Best regards

Our architect estimates: 194 m³ x 140 EUR = 27 TEUR. For a garage of this size with a flat roof, in my opinion a realistic price (aside from the fact that we will ultimately build the garage ourselves). An offer from a second architect is also in the same range. Offers from contractors as well, or slightly higher.

Our architect calculates: 194 m³ x 140 EUR = 27 TEUR. For a garage of this size with a flat roof in my opinion a realistic price (besides the fact that we will ultimately build the garage ourselves). An offer from a second architect is in the same range as well. Offers from contractors are also in this range or slightly higher.

What are the basic dimensions of your garage?

Hello,

OK, that probably means that our 145 EUR per m³ is too low.

In my experience: yes.
Costs for a masonry garage 3 x 6 with FD - approx. TEUR 9 (for comparison 45 m³ x € 145.00 = € 6,525.00), masonry garage 6 x 6 with FD - approx. TEUR 18 (for comparison 90 m³ x € 145.00 = € 13,050.00), masonry garage 3 x 9 with FD - approx. TEUR 14 (for comparison 67.5 m³ x € 145.00 = € 9,778.00)

But what about the house? Can you calculate with 300 EUR per m³ here or is this value also too low?

I can hardly judge that, since I hardly ever calculate houses or sqm/living area by cubic meters; only architects do that. They can do it because the exact construction price becomes concrete only with the receipt of the tender results.

You surely have the information on the square meters/living area? Calculate these for KfW with € 1,500.00/sqm/living area - unless you plan an elaborate roof, otherwise more; if the result roughly matches your architect’s forecast, the € 300.00/m³ are also correct. If not, you will already know what to expect when the tenders come in.

Kind regards

First of all: The term umbauter Raum is long outdated but persists stubbornly. Referring to DIN 277, I assume that Gross Volume (BRI) is meant. A cost estimate based on volume is permissible (as Bauexperte has already mentioned), but I consider this calculation method for single-family houses to be impractical and prefer a calculation based on living area - this also allows for a much better comparison.

To illustrate why I consider a calculation based on m3 to be not very sensible, an example:
Consider a fully two-story house with a hipped roof. Depending on the size of the roof, the attic space is fully included as volume. The same house with a flat roof would have significantly less volume - but it does not become cheaper because of this.

In this respect, the 1,500 Euro/m2 living area mentioned by Bauexperte is realistic for a house equipped with an average standard.