150 sqm detached house - demolition & new construction - recommendations?

Hello everyone!

First the obligatory part:

Development plan/restrictions
Size of the plot 800 sqm
Slope Yes, steep
Site coverage ratio 0.3
Floor area ratio 0.6
Number of parking spaces 1
Number of floors Basement + Ground floor + Upper floor
Roof type Gable, 40° without dormers
Architectural style modern
Orientation South
Maximum heights/limits none known
Further requirements the development plan is very old, therefore few requirements.

Requirements of the builders
[B]Architectural style, roof type, building type simple building with gable roof, knee wall 120 cm
Basement, floors Basement extended as terrace
Number of people, age 2 adults + 2 planned children
Office: family use or home office? used little
Guest sleepers per year 3 (who are allowed to share our bathroom)
Open or closed architecture open
Conservative or modern construction modern
Open kitchen, kitchen island yes & yes
Number of dining seats 6
Fireplace no
Music/stereo wall yes, in the living room
Balcony, roof terrace Terrace on extended basement
Garage, carport Garage in the basement
Utility garden, greenhouse yes, already existing
Further wishes/special features/daily routine, also reasons why this or that should not be yes, the entrance is on the back of the house. We do not want to waste any area facing south for the entrance and also want the entrance on the ground floor, not in the basement.

The basement is deliberately planned without windows; a door with a glass element could be installed in the utility room. If the plot didn’t have a slope, we would also build without a basement. So we mainly use it as a garage. Basement topic will come up again. Windows on the sides are few, since you would only look onto the neighboring buildings there.

House design
Planning by: by us, self-drawn
What do you particularly like? Why? open living area, large windows facing south
What do you not like? Why? Depth of the basement, see below
Price estimate according to architect/planner: we have not reached this stage yet
Personal price limit for the house, including equipment and demolition: 350,000€
Preferred heating technology: heat pump, if the budget allows in the end, preferably with deep drilling

Briefly about construction/budget:
- Basement as precast basement
- House in timber frame construction
- Roof tiles from the existing building, roof was renewed just last year
- Electrical (except house connection and meter cabinet) as DIY, it should be a Loxone system, many components are already available
- Photovoltaics with storage as DIY, if compatible with funding
- Floors and painting as DIY
- Staircase ground floor to upper floor as DIY
- Sanitary, central ventilation and heating self-contracted
- Bathroom + WC as DIY
- Blinds/raffstores only as sun protection, no need on the north side
- We do not want golden faucets, but also no “standard goods” sold by prefab house manufacturers with 200% markup

Additional construction costs can be kept low, the plot is already family-owned, construction electricity and water can be provided by neighbors.

Demolition costs were estimated at about €20,000 by the provider.

Our preferred house supplier builds to KFW40 standard; with photovoltaics we could achieve KFW40+.

If you have to give up, on which details/extensions
- can you do without: size of the basement
- cannot do without: large windows + terrace facing south, photovoltaics because heat pump desired and e-car present

Why has the design become as it is now?

Currently there is an existing building from the post-war period on the plot. This will be demolished. The footprint of the house cannot be changed very much because the plot is rather narrow and sloping. When demolishing, the matching excavation pit will automatically be created. We want to use both the view to the south (cannot be built over anymore, here there is only a narrow street ending in a dead end in front of the house) and the view to the north into the garden with adjoining forest.

What is the most important/basic question about the floor plan summarized in 130 characters?

What can be optimized? The last meters of the basement toward the slope (behind the stairs) are actually unnecessary for us. Would it make financial sense to shorten the basement and only extend the basement ceiling a bit? Material remains from the demolition, which might be used here for backfilling (broken up directly on site), so it would no longer have to be disposed of expensively?

Which architect should we best commission? Have the house planned by the provider or choose our own architect and, for example, tender the basement ourselves?

Is the budget realistic?

We look forward to your suggestions!

Best regards
Noel

What is included in the budget?
In the end, you want to build a shell construction house. The interior finishing is done entirely by EL or through self-contracting. Did I understand that correctly?

Do you have enough helpers with expertise? This cannot be done in 20 weekends and 14 days of vacation.

I would build with a regional, stone-by-stone company. They also take care of the earthworks, etc.

A big question mark is the structural engineer and possibly the geologist. The two imposed five-figure additional costs on us.
Do you have more precise elevation data?

Demolition
Crushing is supposed to be cheaper than disposal? Even with our quantities, everyone declined, saying crushing is too expensive. Only one offered it to me and it was expensive.
Where do you want to use the material if you want to use the old excavation pit?
Do you want to leave the material unchecked on the property?
Post-war building material is not without issues – at least there was agreement among the demolition companies. Something was baked into stone there and it could be more contaminated than the very old ammonia-infested cowshed.

Hi haydee,

The budget includes all planning services, materials, and labor costs for all contracted trades and helpers, as well as incidental construction costs. And the demolition.

Basically, "shell house" fits quite well, but I don't like this kind of pigeonholing. However, we do not want to do drywall work ourselves (except maybe small things, partition walls in the bathroom, etc.). Walls should be handed over by the builder at least at Q3 level.

We are located relatively rurally here, I have many craftsmen (some self-employed) in my circle of friends, so I definitely want to contract some work myself.

I am aware of the time effort. However, I can plan my work more flexibly through my self-employment than someone who is employed. In addition, we currently live in a condominium, so there is no strict schedule because the apartment is being terminated. 2-3 weeks longer in interior construction would therefore be no problem, for example.

A stone-on-stone construction method is not an option for us, but that is probably a much-discussed fundamental decision. I see the earthworks more with the demolition company because, roughly speaking, it is limited to foundations and backfilling. The "excavation pit" results from the demolition.

A soil survey is definitely necessary, but the subsoil is very rocky and should be very load-bearing. None of the currently existing houses show settlement damage or similar. I am coordinating with the architect regarding the structural engineer.

Regarding the demolition, I have so far only one opinion from an acquaintance who is self-employed in this field and has offered me the demolition. In his opinion, the building structure is good at first glance and not contaminated. As far as the use of the material is concerned, I am open to suggestions. I do not necessarily have to reuse it but want to save costs if possible. I find the price quoted for the demolition and crushing cheap but have not yet had a comparison.

The ground floor will be very dark; more windows on the sides should be planned. Additionally, it is not easy to access the garden from the living area.

Do you go around the house now to find the entrance? Why so complicated—?

Where does the woman leave her clothes? I don't understand the layout. Can you please mark your basement and the house on the property? And the section would also be very helpful because of the slope.

Then the budget is too tight.

You need an extremely flexible construction company, the wall structure is secondary. Depending on the height specifications, the basement can be used much better. See the note from YPG.
You want to hand over in Q3, but some parts you take over yourself, which are already partially included in the wall structure.

No, the earthworks are not the responsibility of the demolition company. They do not bury connections, foundations, or refill later.
We had to underpin the old retaining wall in the area of the house before the new retaining wall and floor slab were installed. That has nothing to do with the demolition. It only caused a lot of excavation.
In the past, many buildings in our area were constructed without foundations because the ground was so stony.

Our ground is also rocky. Soil class 5-6. Nevertheless, the retaining wall, floor slab, and first-floor ceiling were designed thicker and the reinforcement adjusted accordingly. To quote the construction company: "Are you afraid of Kim, or why are you planning a bunker?" The architect had never planned such a thick solid wood ceiling before.

You can't see what is inside the stones. The part of the house renovated post-war caused everyone stomach aches. They are grab bags.
Consider whether you need the material regardless of pollutants.
Depending on the size of the house, I don't necessarily find 20,000 cheap.

And you need storage space for everything away from the construction pit, crane area, etc.