Cost estimation for interior finishing, any experiences?

Thank you first of all for the detailed consideration. A few points regarding what I have calculated.

For the drilling, I took the highest per meter price I found with a simple Google search. Purchasing the land assumes that you do not encounter any "extreme" soil layers. According to a real estate agent who sells many plots in the town, the soil survey can be done at your own expense before purchase.

For the €7000 for the heat pump, I took a sample model with high performance including all materials.

The roof and stairs are not yet well-founded, as I estimated very roughly here. I probably have to rethink that. A chimney on the roof is not planned, since only the heat pump and no tiled stove will be used for heating and domestic hot water. Or have I overlooked something that might require a chimney?

The front door is a lot, I found examples on one side that already seemed expensive to me, I may have to adjust that upward.

Earthworks are included in the ancillary building costs and assume soil class 3. We will do the driveway ourselves only if absolutely necessary.

What I really forgot are the costs for cable ducts/pipes in the house.

Thank you very much in advance for the valuable tips and hints about where I am completely off. If I now have a concrete offer made for us, I have already gained better ideas.

Sorry that I’m butting in here. I find your approach very questionable. May I ask what you do for a living? Do you think that with a simple internet search, I could name all the costs that are usual in your professional field? Find yourself a specialist (general contractor/architect), what you’re doing is a waste of time. What good is it to you if you have your costs now, but in the end nobody builds or delivers at those prices? I haven’t even looked at your prices in the least (I have no idea about that) but one thing stood out to me: Where are the disposal costs for your excavation?

Do you think, with a [...] internet search, I could name you [...] costs that are common in your professional field?

A clear yes.

What use is it to you if you know your costs now, but in the end no one builds or delivers at those prices?

Quite simply, then it cannot be built on the scale we want. Nevertheless, I can estimate in many areas how realistic the prices are.

Where are the disposal costs for your excavation soil?

I have read the construction and service descriptions from several providers. They always said something like the excavation is stored on the property. Only if the property is too small will the excavation be transported away at extra cost. I called the building authority in the municipality to ask if this is even allowed. It is not a problem. What is not yet foreseeable whether additional costs will arise is the question of whether the groundwater for the construction pit needs to be lowered. This is an item that cannot yet be calculated without a soil survey.

I definitely think it makes sense to research on the internet before naively signing a contract in full trust with a sales advisor or an architect you do not know. Just an example: When I read in various construction diaries that a handful of workers install 200 m² of insulation defect-free in one day and then find the price for insulation materials (certainly quality products) around 10 EUR / m² for the thickness offered, I expect costs around 3,500 EUR. If the price is significantly cheaper, I would wonder what is actually being installed? Are the workers legally employed? If the price is significantly more expensive, I would wonder what profit margin is actually being calculated here? But if I had not informed myself beforehand, I would have no idea what such insulation actually costs and what effort it takes to install it.

Just as a question to the other builders, provided a general contractor is used: Were all individual prices for the trades listed for you? In my offers, there is always only the price for the house according to the scope of work and then the additional or reduced calculation.

Are you aware of the amount of earth you want to store? You will have almost 500 m³ of excavated material, enough to create a nice sledding hill. You need to have the space for that first.

Just a question for the other builders, if building with a general contractor: Were all the individual prices for the trades listed for you? In my quotes, it only ever shows the price for the house according to the construction service description and then the additional or reduced calculation.

Exactly like that.... Individual trades don't really interest me. I inquired in advance about what a house roughly costs. Then I compared providers. In the end, the right price at the bottom right counts for me; I don't care how the construction company manages that. If I want to know that, I have to work with an architect. For the interior finishing, I had the individual prices given to me because I could have awarded those myself. But honestly, it almost never made a big difference. Except for laying the floor, that definitely can be done cheaper. And I could save something on the interior doors... but it's too stressful for me to look for another provider now for maybe a few hundred euros.