Costs for single-family house (percentage distribution?)

Hello everyone here in the forum,

we would like to build a single-family house in the near future and would like to do a rough cost calculation.
Are there any percentage guidelines? For example, shell construction 40% of the total costs, windows 10% of the total costs, etc., heating + water %, bathrooms %, ....

I would like to create a table where all areas are recorded and we set a limit for our entire house including furnishings and then distribute it proportionally so that we can see all costs for the individual areas and orient ourselves on the offers or make cutbacks accordingly.

It should be a single-family house with a flat roof (approx. 150 sqm) + basement and garage.

Looking forward to your contributions.

Thank you very much & best regards
Andi

I would like to create a table that covers all areas and set a limit here for our entire house including furnishings, and then allocate it proportionally so that we can see all the costs for the individual areas and use it as a guideline for the offers or make concessions accordingly.

And if the budget doesn’t fit, do you leave something out? The last trades? Or the item at the end of your table?
Just because your specialty roof might be twice as expensive as a gable or hip roof, you can’t just leave half of the ceiling undone.
One person invests more money in the roof, another has the exterior walls especially insulated, so the shell costs more, a third has an expensive heating system, and the fourth has golden faucets and installed home automation. In total, everyone ends up with the same price per square meter, only the distribution is different each time. You see, that doesn’t work like that.

Unless you’re building with a general contractor (with whom you get a price for the entire house plus special wishes), you have an architect or an engineering firm, or a construction supervisor who can give you a rough idea of what costs will come up for you, specifically tailored to your house/plot/floor plan/special requests.

Thank you very much for the quick response.

We will be building with an architect, so we will have them as our contact person.

Of course, I understand that certain areas cannot simply be omitted. But compromises can and must be made. You can’t have everything exactly as you wish – for that, you would have to win the lottery. At least in my case.

For example, with heating, you might be able to leave out the solar heating even though you would like to have it. The same goes for windows: does every window need to be a lift-and-slide door, or would fixed glazing be sufficient in some places? I think this would be easier to manage with a rough percentage distribution.

If you want to contract each trade separately, go to the building materials store and look at the unit prices, roughly 60% is installed when the shell is up. Of course, it also depends on how high-quality the rest of the house turns out. Look at the prices for shell houses, then you will have a direction to go.

Make a list in advance with your special requests and corresponding prioritization (mandatory, must, can, would be nice, etc.) If then the price estimated by the architect exceeds your budget, you will remove items from the list. It may happen that you end up with a standard level in one trade, while in another trade you have a higher standard or luxury, because that is where your prioritization lies. The house should be "your house" and built according to "your wishes" and not based on any percentages. It should be clear that probably 99% of home builders have not won the lottery and cannot fulfill all their wishes. Everyone has to make compromises. This probably already starts with the different prioritizations between your wishes and those of your wife.