Low-cost single-family house planning

Hello, a flat roof is among the most expensive because it is very difficult to seal, and water management is not simple either. Then the structural engineering must be appropriate as water pockets and snow pockets can potentially form. A purlin roof with a central purlin and about 30-35 degree roof pitch + two masonry gable walls are probably the most cost-effective.

The dismantling of a flat roof sealing and its disposal after 10-15 years burns your precious money...
A bedroom in the basement has the disadvantage that due to the ground conditions you have to build a waterproof basement (concrete basement) and that has the worst possible building physics properties.

Regarding the electrical system, you underestimate how many cables you have to fit into the baseboard. This is not comparable to chasing slots in the shell construction.

The exterior stair lintel is not expensive, only the consequences... sealing, insulation at the connection between stair and exterior wall, sealing of the door, etc.

Addition: most pipes for water, electricity, and data are laid on the raw ceiling under the screed in new buildings anyway.

@Bratac put it quite well.

I can also understand the whole thing as a layman and hope to convey it to you: The important thing in building a house is protection against water - both top and bottom.
On top, it’s the roof. To close a flat roof in such a way that it meets all requirements and the water flows where it is planned, is already very expensive.
What then makes your roof expensive, you want to tear off again after about 10 years to use it as a base for another extension. That would mean double costs for the roofing. By the way, I can imagine that a planned flat roof might not even have the structural requirements. That means: a flat roof doesn’t have to carry much weight - so if you already plan this flat roof now like an intermediate ceiling, the roof will cost you just as much again. What about the staircase opening? Either you leave a hole in the ceiling now or you make a breakthrough when adding the extension... I’m already shaking as I write this...
The dirt will ruin everything - forever. You won’t be happy anymore, and you will curse yourselves: we should have planned a proper roof right from the start. Living space under a necessary but inexpensive roof is still the cheapest living space.

At the bottom is the floor slab. You want a basement. That means sealing again - costly sealing for living space, which due to the concrete walls does not provide a good living climate, at least not as good as a timber frame room or a masonry room. Then the garage integrated into this floor means extra insulation effort, because the garage is open to the outside, but a residential building must be built according to energy saving regulations.

Regarding the electrical system: there are rules for safety. Horizontal installation is only allowed in exceptional cases; otherwise, the cables go directly on the floor to the spot where they are pulled vertically. Installation at... guess where... baseboard height is prohibited in a new building.
Whether forbidden or not allowed or should be avoided... I do not know.
I’ll start again and won’t delete. I only know that certain distances must definitely be maintained above and below. And what does common sense say? Mine tells me that cables must always be installed in such a way that you do not get direct contact with them later. A small nail in a floor molding can already cause a smoldering fire and wipe out a family.
We are also talking about cable bundles here that have more volume than a single cable hidden behind a molding.

Exterior basement stair lintel... here we are back to sealing.

You are planning a house with brute force that will never become a home because it will be a permanent construction site with dirt and mess and constant unrest.

For me, financing that should be paid off without reason within 10 years is an oppressive financing.

I would also be surprised if the development plan allows flat roofs, gable roofs, 1- and 2-story buildings, as well as building heights from/to about ± 5 meters. Usually, the development plan goes in one direction and excludes the other!

Regards Yvonne

Good evening,

BratacDD and Yvonne have already given you very good answers.

By the way, my assumptions are based on a fictional house construction, whether it is a raised or basement cellar, ridge height, soil survey/clay soil is initially disregarded and must of course be taken into account.

It can’t be entirely "fictional," since further down you refer again to a cellar with a plinth.

- No one talked about concrete walls (there are other materials as well). I assume you refer to living in concrete walls when you mean the basement.

A cellar made of concrete walls "could" be a point to consider; I have clearly pointed out the still missing soil survey.

I don’t know what you do in the bedroom

Presumably nothing different from what other people do there ... sometimes children are supposed to appear there as well

but for me it is totally okay to have this in the cellar, especially if it is a raised cellar with sufficient daylight. The same applies to the full bathroom, utility room, and garage in the cellar.

"I" would have a problem if it "had" to be a concrete cellar. Besides, the cellar is the most expensive room to generate living space. Besides the enormous costs for the cellar itself, there are additional costs for the expansion. If a full-fledged bathroom is to be created, costs for a lifting system with double chopper pump in your calculation "can" be taken into account (drainage above the backwater level) "must."

- Electricity in the skirting boards, why not? What speaks against it? I ask for clarification.

DIN 18015 ... ?

Regards from the Rhineland