Single-family house with stepped floor - Feedback/Discussion/Tips/Ideas

Hello,

The construction in this form was more or less already approved by the planning office.

Sorry, but from my experience, "more or less approved" does not mean much. Only when the caseworkers remember the "more or less" during the building permit process will it actually work.

For example, four years ago I discussed a Bauhaus design in a § 34 area explicitly with the responsible caseworker at the building planning office of the city of Rösrath—especially regarding the height of the building—before we submitted the building application. Nevertheless, it was rejected, and we had to set the entire building lower, resulting in the garage sometimes not remaining undamaged during heavy rain. Or the building planning office of the city of Neuss caused a comparable chaos several years ago, which I was only able to resolve with the help of elected representatives. I could list countless examples here; therefore, I always recommend having statements from the building planning offices confirmed in writing.

Due to the statics, the ground floor will be built in solid construction with a concrete ceiling, the upper floor in a light timber frame construction.

Why the material mix regarding the building envelope?

Regarding the capital investment: we are calculating with about 180 TEUR pure construction costs including engineering services but excluding land, garages, utility connections, and extras such as geothermal, fireplace, photovoltaic. Overall, we are at about 250 TEUR plus land.

Have you made an estimate or do you already have quotes?

I rather assume that the construction price for the planning will be in the area of TEUR 215/220, including architecture, statics, and soil survey. Plus incidental construction costs TEUR 35-10, possibly additional foundation costs due to the land location and the case that the neighbor has a basement, plus garages, plus painting and flooring, plus exterior work, and plus a reserve for extras. I see the total investment rather in the range of TEUR 300-320.

Rhenish greetings

Fortunately, it is not the [Bauamt Neuss]. But our architect has discussed this with the [Planungsamt]. And I assume they will do it properly. They haven’t been doing the job just since yesterday and are well-established architects. The price is a calculation by the architect, as well as the decision to change the material for the statics on the upper floor. The neighbor does not have a basement.

How do you come to the costs or what is your calculation basis?

Hello,

But our architect discussed this with the planning office. And I assume that they do it properly. They haven’t been doing the job just since yesterday and are well-established architects.

You didn’t write anywhere that your architect spoke with the planning office or did I overlook something? I have been doing this job for a very long time as well; nevertheless, I am not immune to shipwreck – for exactly this reason I wrote my comment.

The price is a calculation by the architect

A first cost estimate?

... as well as the decision to change material regarding the statics in the upper floor.

I would like to understand that. What reason did your architect give you? As a rule, architects are the first to protest when material mixing is mentioned.

How do you come to the costs or what is your calculation basis?

The calculation basis is your floor areas, broken down to the approx. living area (LA) of about 134 sqm, the building style of the house, and the assumption that a KfW 70 efficiency house is being built.

In the Rhineland, a rough calculation of the expected building costs for a conventional single-family house can be very well set at €1,500.00/sqm/LA; this number marks a value derived from our completed construction projects and is constantly updated. It is cheaper in the north and east, but more expensive in the south of the country. If I read the threads here, I am usually quite accurate with my estimates when a financially healthy (serious) company with medium equipment and quality has received the building contract.

However, you don’t want to build a conventional single-family house but have decided on the Bauhaus style and additionally a stepped floor (SF). This makes it clear that the basic price/sqm/LA has to be set higher because this building style requires significantly more craftsmanship. For example, the sealing of the ground floor upwards in the area where a roof terrace is to be created by setback of the SF; the same applies to the design of the SF in a different material as well as the flat roof itself. According to all experience, we are then talking about construction costs of €1,600.00–1,700.00/sqm/LA; including soil survey, architectural services & statics as well as a modern heat generator (for example, gas condensing boiler with heating support and solar domestic hot water heating or also an air-water heat pump).

You can find the typical additional construction costs here:

https://www.hausbau-forum.de/ratgeber/bauherrenhilfe.422/bauherrenhilfe-vor-vertragsabschluss.424/bausumme.662/#Baunebenkosten%20und%20Grunderwerbsteuer

Because your construction project is to be realized in a fairly tight existing situation, I have suggested that you create additional reserves for possible extra foundation costs. If such costs do not occur, you have more funds for one or the other extra; if they do occur, you have accounted for them in your budget. You would not be the first and certainly not the last builder who – even with a secure income assumed – is denied additional financing.

The rest consists of a lump sum for painter work and floor coverings as well as outdoor facilities in EL in the amount of TEUR 25, a prefabricated double garage in the amount of TEUR 11 and a reserve of TEUR 10 for one or the other extra.

Best regards from the Rhineland

I had forgotten to mention the architect. But that a conversation with the planning office took place was stated somewhere further up. But that’s not a problem. I think complications can always arise, but if you always assume the worst, no one would dare to build a house anymore.

This is indeed a first cost estimate, our architect has built several projects using SG construction in the past, and the calculations from previous builders were always acceptable from their perspective. Of course, additional costs should always be considered, but if everyone adds a bit more, you quickly reach the limit with the calculation.

Since we own the plot and (if the excavator does not dig up the whole garden) this is already finished, we don’t even have to spend a euro on the existing pool, not even for fruit bushes and lawn. Of course, there is still some work left, which we have taken into account.

In addition, we have a roofing company in the family that might take on the appropriate trade if necessary. Of course, salaries have to be paid there as well, but at least the materials are accounted as equity.

Honestly, I am not worried about a (possibly necessary) refinancing.

Regarding the material mix, do I have to mention the word structural engineering again? The execution as timber frame construction is lighter than solid stones, isn’t it? The walls on the upper floor don’t actually stand directly on the load-bearing exterior walls on the ground floor. I didn’t find the idea rosy at first either, but the architect came up with it.

Our architect calculates about 240 euros per m³ plus taxes + engineering services, etc. I find it very difficult to directly compare the individual cost items 1:1.

Basically, I also think about the latter, but even there you don’t know who you will get and with what quality. And even here there are price differences beyond good and evil.

If it is supposed to be proper, one probably sets standards equivalent to those of an architect's fee.

So, a new basis for discussion has arrived.

Of course, it is still basically the same house, our architect has finally (verbally) agreed on the shape (setback storey with flat roof) with the building authority. It is a medium-sized suburb with a pleasant relationship between the client, architect, and building authority. Of course, someone can still throw a spanner in the works, but basically, it has been a harmonious relationship so far. You don’t always have to go through the wall with your head. I don’t expect any complications for the time being.

1) The idea of converting the upper floor into a granny flat appealed to us personally. Either for our own child or who knows for whom. Of course, it is not a full-fledged apartment, but as a 1-room kitchen bathroom for students quite interesting. So the idea was there, but we could not yet imagine the implementation. The current design actually pleases us in the upper floor, especially since there is space for a washing machine/dryer both upstairs and downstairs, and a single kitchen can be installed upstairs with little effort.

2) The windows facing the street (to the right) are exclusively in the utility room or bathroom and should therefore have a relatively high sill height and hence be wide but shallow.

3) In the kitchen, the door to the hallway was omitted to accommodate more tall cabinets, to compensate for the lost storage room/kitchen pantry.

4) The forgotten chimney was inserted in the living/dining room. Upstairs, the chimney will continue along the outer wall. Cleaning is even possible from the outside in the passageway to the existing building. This pleases the chimney sweep, and my wife even more.

5) The TV in the living room is not the focal point of the household, so it will be placed “somewhere” on the wall where it does not disturb. If there is really a lot of glare, we still have shutters as a backup.

6) The master bedroom has moved to the ground floor, but we did not want to widen the living room at its expense, so our suggestion was to place the wardrobes in the room; our architect made this solution. Since our bedroom is mainly a bedroom and clothes storage, we find this solution, or something similar, even better than our original idea.

7) Now something about energy/energy saving ordinance/KFW70... He basically shares the criticism/concerns raised here about the comparatively large exterior envelope compared to other houses. He also expects somewhat stronger insulation than in the typical house-building style, but since this is not the first house with a setback storey, he does not see an extra expensive unsolvable problem. The structural engineer, who also prepares the appropriate energy calculations, will be involved shortly.

8) The difference in floor height between the room and the roof terrace only made him look at me questioningly... Option 1: 10 cm screed, or he suggests that the roof terrace is accessible by a step. Nowadays, this is unfortunately hardly sensibly avoidable because of insulation. But he promised it looks quite good that way. I also would not know what should look bad about it. We could also build without a roof terrace, but that would be wasted space. I share this assessment.

Now have fun with further lively discussions. What do you think? Better or worse than before?