Budget calculation single-family house 160 m²

Hello,

we are currently planning our budget for a single-family house. Here are roughly the key data that it should have:

- Region Berlin/Brandenburg
- 160 m² (or possibly less with an optimal floor plan)
- 1.5 to 2 floors (depending on what the respective development plan allows)
- preferably (flat) gable roof, because it is the most cost-effective
- KFW 40 plus, because due to the climate crisis we think it is right that the house is as energy-efficient as possible, then with air-to-air heat pump + photovoltaic
- living + dining area, 4 bedrooms, 2 bathrooms (we are currently planning for 3 children, well)
- we are okay with a rather minimalist style, so bay windows, recesses, corner windows, smart home and other things we want to save on
- however, large window surfaces are welcome
- basement, insulated, so it can be used flexibly later (we are about 75% sure that we want this)
- ideally wooden terrace, double carport, if still possible
- we would like to go to an architect so that we get a design that fits us, without sales pressure and advisor talk and without things we don't need
- solid or wood and/or prefab etc. we don’t care at the moment

Here is our rough calculation, assuming that a plot is cleared and ready to build:

House (construction, technology)	360,000.00 €
Basement	30,000 €
Outdoor facilities	21,500 €
Equipment (kitchen etc.)	20,000 €
Additional construction costs:
Architect	32,000 €
Expert reports etc.	3,500 €
General additional costs (electricity/water connection)	3,000 €
Miscellaneous and reserve	30,000 €
	= 500,000 €

Our budget limit for everything (plot/real estate agent left out here for simplicity) is about €470,000. KFW subsidy would get us to about €500,000. We have included a buffer. Unfortunately, you can read a lot online about prices, starting from the foundation slab, turnkey, then experience reports... prefab houses of this size are "from" €250,000 and they even have bay windows and other stuff included... there should be some leeway. Sometimes someone offers the complete house with everything for €350,000, sometimes someone is already at €450,000 and doesn't even have additional costs included. In short: the more we read, the more uncertain we become.

Is the above calculation realistic with our wishes? Do we have to calculate something differently? Should an architect be able to manage that?

Basement	€30,000

Depending on the soil, you only get the excavation transported and disposed of! For 100 m2 floor area and insulated (suitable as a living basement and not as a coal bunker) you are more likely at 70 to 100 thousand euros.

Outdoor facilities

€21,500

for a completely flat plot, restraint and the essentials yes. Wooden terrace and double carport rather no.

You see, it strongly depends on the specific plot and the soil.

- KFW 40 plus, because we think it is right due to the climate crisis that the house is as energy efficient as possible, then with air-to-air heat pump + photovoltaic

It does not have to be particularly energy efficient because of that, KfW-40plus is initially only a calculation method! Plus because of a battery you do not save CO2 overall, because the battery also requires some in production and you can only store something for a few days, hardly for the winter when you really need the heating. Insulate, yes, as much as possible. That is, in first approximation, the actual consumption.

And KfW but only as much as the difference between additional costs and the subsidy allows. That depends!

PS: a shed roof is even cheaper than a gable roof.

KfW40+ and insulated (residential) basement: The calculation for 160 sqm is too tight there. It won’t work...

Hello,

so we want to build 160sqm plus basement with your budget, how much budget is left for the terrace and garden will show next year.

However, we have planned at least 1 year of afternoons plus weekends as own work plus very active family and friends. For that, Brandenburg is probably cheaper than Bavaria.

So it's definitely not easy.
But if I understood correctly, you first need a plot of land anyway.

Thanks first of all for the initial answers!

Basement	€30,000

Depending on the soil, you only get the excavation transported and disposed of for that! For 100 m2 floor area and insulated (as a living basement and not suitable as a coal bunker) you are rather between 70,000 and 100,000 euros.

Hmm, that’s interesting. I had assumed relatively low average values of a few thousand euros for the excavation. Unfortunately, I found nothing about the insulation. It doesn’t have to be a living basement right away, just whitewashed walls would be nice. We just didn’t want to have a coal pit as you said, where you want to get back to daylight after one minute. But we are not married to the basement and could also imagine a utility room + technical room before it fails because of the basement. So thanks for your insights!

Outdoor facilities

€21,500

With a completely flat plot, restraint, and the essentials, yes. Wooden terrace and double carport rather no.

You see, it depends heavily on the specific plot and the soil.

Yes, I think so too. We hope to manage with that. What we need first is an access road/path and that’s it.

PS: a monopitch roof is even cheaper than a gable roof.

Oh, thanks for the tip. That’s something we can actually take into consideration. It might fit our ideas.

Unfortunately, I didn't find anything for the insulation. The basement doesn't necessarily have to be a living space for now, just whitewashed walls would be nice. We just didn't want to have a coal mine, as you said, where you'd want to get back to daylight after one minute.

What do you understand by a living basement?

If the walls are already whitewashed, they are also plastered. There is probably already a floor in place, hence a screed. You will also want some windows, and if "living" is possible, you need a second emergency exit, so a slope and a door. And if everything is plastered, there will probably already be electricity. Insulation as well. And if you don't want to go down a ladder, there will also be an interior staircase and a stairwell below. Having the interior walls already in place would also not be pointless. You wouldn't want to run heating surface-mounted at a later time... so now think about what else is missing for "living" upstairs... okay, the most expensive rooms called bathroom and kitchen.

But otherwise? Why should you calculate 2500 euros/m2 on the ground floor and upper floor and less than 1000 on the basement when civil engineering is always more expensive than building construction?

But we are not married to the basement and could also imagine a utility room + technical room before giving up on the basement.

Then better build 10 m2 more per floor, a utility room with shelves downstairs, technical equipment under the stairs to the upper floor, and a multifunction room upstairs (wall shelves, office, pull-out sofa). An extended prefabricated garage for 10 TE where another 10 m2 will arise at the back as a storage area and a carport next to it. And visit the recycling center more often ;)