ᐅ Floor plan: New construction on an existing bungalow basement, one-and-a-half stories
Created on: 19 Dec 2022 01:12
M
Mal BauenM
Mal Bauen19 Dec 2022 01:12Hello to all forum members,
We are still relatively early in our building project and have many fundamental questions to clarify. Nevertheless, I would like to introduce the project here.
We recently became owners of a prefabricated bungalow from Streif Haus, built in 1987. It has a full concrete basement (by Betonkemmler).
Our plan is to demolish the bungalow down to the top edge of the basement and build a new house for our family (currently four, eventually five) on top. The existing basement (very solid construction) is to be integrated as a utility basement including a technical room. At the same time, the heating system will be modernized from oil heating to a heat pump.
Currently, we are in contact with both prefabricated house suppliers (Weberhaus, Danwood) and solid construction companies (Denkinger). The property is located in Baden-Württemberg (southern Baden).
Even though the floor plan is only a first draft, I would like to present it here for feedback (summary below).
In particular, I hope to get some thoughts on the following basic questions:
Here is the summary sheet (key points).
Many thanks in advance for your input, comments, and critiques. I will gladly report further developments here in the thread.
Development Plan / Restrictions
Size of the plot: 615m² (6620 sq ft)
Slope: North/South: <0.5m (1.6 ft) over 18m (59 ft), West-East: approx. 2m (6.6 ft) over 33m (108 ft) (see elevation profile)
Site coverage ratio: No development plan (Section 34 of German Building Code). The immediate neighborhood contains some generously built plots. We do not want to change the building footprint of the existing house but want to add a double garage (not currently present).
Floor area ratio: No development plan (Section 34 of German Building Code)
Building envelope, building line and boundary: No development plan (Section 34 of German Building Code). Property boundaries and existing building shown in aerial photo attached
Edge development: None
Number of parking spaces: None
Number of floors: 1.5 stories
Roof type: Gable roof
Architectural style: Modern detached family house
Orientation: see aerial photo. Entrance (currently): north
Maximum height/limits: No development plan
Immediate neighbors: Northern neighbor: 2 stories with flat roof. Southern: 1.5 stories with hipped roof. Western: 1.5 stories with gable roof.
Client Requirements
Style, roof form, building type: We want to transform the existing bungalow into a classic 1.5-story detached house with a gable roof and possibly shed dormers.
Basement, floors: Utility basement (existing, concrete basement), ground floor (living), upper floor (sleeping)
Number of persons, ages: Our family currently has four members (ages: 32, 30, 2, 0), with another child planned
Space requirements on ground and upper floor:
Ground floor: living room, kitchen (possibly with pantry), room for home office or guest room, guest WC with shower, cloakroom
Upper floor: master bedroom, 3 children’s bedrooms, bathroom
Office: family use or home office: Home office (100% for me)
Overnight guests per year: Few, less than 5 guests/nights
Open or closed architecture: Rather closed. Ability to separate kitchen and living room would be desirable.
Conservative or modern design: Modern
Open kitchen, kitchen island: Kitchen island not mandatory. Partly open kitchen: separation from living room would be good.
Number of dining seats: 5-8
Fireplace: Only if budget allows, not mandatory
Music/ stereo wall: No
Balcony, roof terrace: No
Garage, carport: Double garage
Utility garden, greenhouse: No
Further wishes/special features/daily routine, including reasons for preferences or exclusions: The technical room should be located in the existing basement (e.g., in the former oil heating room). A sensible circulation concept is very important: front door/upper floor stairs/basement stairs. Ideally, short distances between garage and house as well as good accessibility of rooms within the house.
House Design
Designed by: Initial draft from the prefab house supplier after first meeting
What do you especially like? Why?: (Almost) all room requests fulfilled. Good accessibility of upper floor rooms via centrally located landing. Short distances from garage to house thanks to new front door position (west instead of north). Spacious cloakroom area. Living room oriented south/east with a nice view.
What do you not like? Why?: The draft was created after an initial discussion of the project. Some ideas and preferences developed or changed later on by us:
- Existing concrete stairs in the basement will not be used, causing extra costs for upgrading the basement (new stairs, new room layout).
- (Small) pantry for food/storage on the ground floor would be great
- Better separation of kitchen and living room is desirable
Price estimate according to architect/planner: 520,000 € (approx. $560,000), turnkey (including 10kWp photovoltaic system with 10kW storage, fresh air heating with air-to-air heat pump), excluding demolition of existing bungalow, double garage, incidental building costs
Personal price limit for house including fittings: 700,000 € (rough estimate: demolition down to top of basement: 30,000 €, house: 530,000 €, incidental costs including basement statics: 50,000 €, double garage: 30,000 €, kitchen/furniture: 40,000 €, landscaping: 20,000 €)
Preferred heating technology: Heat pump with underfloor heating. If budget allows: ground-source heat pump with deep geothermal drilling. The prefab house supplier prefers fresh air heating.
If you had to give up something, which details or add-ons could you do without: Fireplace, new basement stairs
What can you absolutely not do without: Home office
Why is the design like it is now?
Individualized draft by the prefab supplier adapted to the existing basement footprint after discussing our rough (space) requirements.
We are still relatively early in our building project and have many fundamental questions to clarify. Nevertheless, I would like to introduce the project here.
We recently became owners of a prefabricated bungalow from Streif Haus, built in 1987. It has a full concrete basement (by Betonkemmler).
Our plan is to demolish the bungalow down to the top edge of the basement and build a new house for our family (currently four, eventually five) on top. The existing basement (very solid construction) is to be integrated as a utility basement including a technical room. At the same time, the heating system will be modernized from oil heating to a heat pump.
Currently, we are in contact with both prefabricated house suppliers (Weberhaus, Danwood) and solid construction companies (Denkinger). The property is located in Baden-Württemberg (southern Baden).
Even though the floor plan is only a first draft, I would like to present it here for feedback (summary below).
In particular, I hope to get some thoughts on the following basic questions:
- Has any forum member gained experience with building on an existing basement?
- Is there generally a preferred construction method for our project? We are still undecided whether to go for a prefab timber frame house or a masonry (brick or block) solid construction.
- So far, we have not discussed a double garage with the builders, but it will be needed. Where does it make more sense: northwest or southwest (directly next to the neighbor’s garage)?
- To what extent can the project be treated as a renovation with partial demolition in terms of building regulations? Background: Are there any possibilities for funding (still) available?
- What we want to achieve with the floor plan is short walking distances inside and around the house. Therefore, the main entrance was moved from the north side to the west side. However, since it is on the short side of the house, this results in more corridor space and longer routes inside (e.g., from the front door to the stairs to the upper floor). But as the saying goes, you have to accept some drawbacks — what is your opinion: front door facing north or west?
Here is the summary sheet (key points).
Many thanks in advance for your input, comments, and critiques. I will gladly report further developments here in the thread.
Development Plan / Restrictions
Size of the plot: 615m² (6620 sq ft)
Slope: North/South: <0.5m (1.6 ft) over 18m (59 ft), West-East: approx. 2m (6.6 ft) over 33m (108 ft) (see elevation profile)
Site coverage ratio: No development plan (Section 34 of German Building Code). The immediate neighborhood contains some generously built plots. We do not want to change the building footprint of the existing house but want to add a double garage (not currently present).
Floor area ratio: No development plan (Section 34 of German Building Code)
Building envelope, building line and boundary: No development plan (Section 34 of German Building Code). Property boundaries and existing building shown in aerial photo attached
Edge development: None
Number of parking spaces: None
Number of floors: 1.5 stories
Roof type: Gable roof
Architectural style: Modern detached family house
Orientation: see aerial photo. Entrance (currently): north
Maximum height/limits: No development plan
Immediate neighbors: Northern neighbor: 2 stories with flat roof. Southern: 1.5 stories with hipped roof. Western: 1.5 stories with gable roof.
Client Requirements
Style, roof form, building type: We want to transform the existing bungalow into a classic 1.5-story detached house with a gable roof and possibly shed dormers.
Basement, floors: Utility basement (existing, concrete basement), ground floor (living), upper floor (sleeping)
Number of persons, ages: Our family currently has four members (ages: 32, 30, 2, 0), with another child planned
Space requirements on ground and upper floor:
Ground floor: living room, kitchen (possibly with pantry), room for home office or guest room, guest WC with shower, cloakroom
Upper floor: master bedroom, 3 children’s bedrooms, bathroom
Office: family use or home office: Home office (100% for me)
Overnight guests per year: Few, less than 5 guests/nights
Open or closed architecture: Rather closed. Ability to separate kitchen and living room would be desirable.
Conservative or modern design: Modern
Open kitchen, kitchen island: Kitchen island not mandatory. Partly open kitchen: separation from living room would be good.
Number of dining seats: 5-8
Fireplace: Only if budget allows, not mandatory
Music/ stereo wall: No
Balcony, roof terrace: No
Garage, carport: Double garage
Utility garden, greenhouse: No
Further wishes/special features/daily routine, including reasons for preferences or exclusions: The technical room should be located in the existing basement (e.g., in the former oil heating room). A sensible circulation concept is very important: front door/upper floor stairs/basement stairs. Ideally, short distances between garage and house as well as good accessibility of rooms within the house.
House Design
Designed by: Initial draft from the prefab house supplier after first meeting
What do you especially like? Why?: (Almost) all room requests fulfilled. Good accessibility of upper floor rooms via centrally located landing. Short distances from garage to house thanks to new front door position (west instead of north). Spacious cloakroom area. Living room oriented south/east with a nice view.
What do you not like? Why?: The draft was created after an initial discussion of the project. Some ideas and preferences developed or changed later on by us:
- Existing concrete stairs in the basement will not be used, causing extra costs for upgrading the basement (new stairs, new room layout).
- (Small) pantry for food/storage on the ground floor would be great
- Better separation of kitchen and living room is desirable
Price estimate according to architect/planner: 520,000 € (approx. $560,000), turnkey (including 10kWp photovoltaic system with 10kW storage, fresh air heating with air-to-air heat pump), excluding demolition of existing bungalow, double garage, incidental building costs
Personal price limit for house including fittings: 700,000 € (rough estimate: demolition down to top of basement: 30,000 €, house: 530,000 €, incidental costs including basement statics: 50,000 €, double garage: 30,000 €, kitchen/furniture: 40,000 €, landscaping: 20,000 €)
Preferred heating technology: Heat pump with underfloor heating. If budget allows: ground-source heat pump with deep geothermal drilling. The prefab house supplier prefers fresh air heating.
If you had to give up something, which details or add-ons could you do without: Fireplace, new basement stairs
What can you absolutely not do without: Home office
Why is the design like it is now?
Individualized draft by the prefab supplier adapted to the existing basement footprint after discussing our rough (space) requirements.
H
hanghaus202319 Dec 2022 11:48Which federal state?
Is there a structural analysis of the existing basement?
A complete demolition given the year the house was built?
I would rather recommend demolishing the roof and remodeling it with a knee wall and a steeper roof pitch here.
Is there a structural analysis of the existing basement?
A complete demolition given the year the house was built?
I would rather recommend demolishing the roof and remodeling it with a knee wall and a steeper roof pitch here.
H
hanghaus202319 Dec 2022 12:02You should ask Streif Haus if they can modify the roof. In my opinion, that shouldn’t be a problem. However, don’t mention that you are planning a complete new build.
While you’re at it, be sure to ask for the structural analysis of the existing house and basement. You will need that anyway.
While you’re at it, be sure to ask for the structural analysis of the existing house and basement. You will need that anyway.
Replacing a Streif house from 1987 with a new Danwood would not result in a quality improvement—it would mean redesigning the floor plan for a significant amount of money, which apparently does not play a major role for you?
However, "solid construction" does not necessarily mean "better." The company Streif Haus still exists, and a timber frame prefabricated house can be redesigned either by the manufacturer or another carpentry company (even in timber construction there are load-bearing, bracing, and non-structural partition walls) as well as extended upwards. Considering the large amount of money involved, I would carefully consider whether it might be better to work with the potential of the existing core structure. In my opinion, your initial design does not sufficiently take this "gift horse" into account. I would be happy to provide more detailed advice; my most comprehensive collection on your topic is summarized here in the forum at https://www.hausbau-forum.de/threads/angebot-ueber-ytong-bausatzhaus-bau-auf-bestehenden-keller.39957/page-2#post-514506. My further reading recommendations for you are https://www.hausbau-forum.de/threads/statiker-fuer-grobe-einschaetzung-zur-tragfaehigkeit-gesucht.38054/ and https://www.hausbau-forum.de/threads/neubau-massivhaus-auf-bestandskeller.41443/—so with these you already have a solid foundation of knowledge covering several related cases and questions in different ways.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
However, "solid construction" does not necessarily mean "better." The company Streif Haus still exists, and a timber frame prefabricated house can be redesigned either by the manufacturer or another carpentry company (even in timber construction there are load-bearing, bracing, and non-structural partition walls) as well as extended upwards. Considering the large amount of money involved, I would carefully consider whether it might be better to work with the potential of the existing core structure. In my opinion, your initial design does not sufficiently take this "gift horse" into account. I would be happy to provide more detailed advice; my most comprehensive collection on your topic is summarized here in the forum at https://www.hausbau-forum.de/threads/angebot-ueber-ytong-bausatzhaus-bau-auf-bestehenden-keller.39957/page-2#post-514506. My further reading recommendations for you are https://www.hausbau-forum.de/threads/statiker-fuer-grobe-einschaetzung-zur-tragfaehigkeit-gesucht.38054/ and https://www.hausbau-forum.de/threads/neubau-massivhaus-auf-bestandskeller.41443/—so with these you already have a solid foundation of knowledge covering several related cases and questions in different ways.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
M
Mal Bauen19 Dec 2022 16:06Thank you for the feedback.
We ruled out the option of renovation instead of demolition fairly quickly, although your comments have made me reconsider.
The gap between the current condition and our requirements seemed too large. While 35 years is not that old, even for a prefabricated house, the insulation is outdated (e.g., exterior walls are 18cm (7 inches) thick). Since we also want to update the heating system (underfloor heating) and adjust the floor plan to fit our needs, the house would need to be completely gutted. Then the question was how much of the "free horse" would really remain in our wallet? It didn’t seem sensible to save, for example, just €50,000 (number pulled out of thin air) only to possibly end up planning, building, and living with too many compromises for decades.
But that’s just an insight into our thoughts—maybe more savings are possible through renovation instead of new construction than we’ve realized so far?
Instead of taking the free horse, we will at least keep the "free foal" by preserving the (really good) concrete basement...
Baden-Württemberg
We have a fairly detailed 40-page structural calculation report from the basement company. Additionally, there is a structural safety certificate for the bungalow above the basement ceiling. We also have (less detailed) structural calculations from Streif Haus for the prefab house.
@11ant Thank you very much for the valuable reading recommendations!
We ruled out the option of renovation instead of demolition fairly quickly, although your comments have made me reconsider.
The gap between the current condition and our requirements seemed too large. While 35 years is not that old, even for a prefabricated house, the insulation is outdated (e.g., exterior walls are 18cm (7 inches) thick). Since we also want to update the heating system (underfloor heating) and adjust the floor plan to fit our needs, the house would need to be completely gutted. Then the question was how much of the "free horse" would really remain in our wallet? It didn’t seem sensible to save, for example, just €50,000 (number pulled out of thin air) only to possibly end up planning, building, and living with too many compromises for decades.
But that’s just an insight into our thoughts—maybe more savings are possible through renovation instead of new construction than we’ve realized so far?
Instead of taking the free horse, we will at least keep the "free foal" by preserving the (really good) concrete basement...
hanghaus2023 schrieb:
Which federal state?
Baden-Württemberg
hanghaus2023 schrieb:
Is there a structural analysis for the existing basement?
We have a fairly detailed 40-page structural calculation report from the basement company. Additionally, there is a structural safety certificate for the bungalow above the basement ceiling. We also have (less detailed) structural calculations from Streif Haus for the prefab house.
@11ant Thank you very much for the valuable reading recommendations!
I know a Streif house in the family about the same age as yours. The house is in good condition. There have never been any problems or major renovations—except that the roof was extended and a large dormer was added. Of course, it is almost 40 years old and reflects the building standards from 40 years ago. But it is still far from being ready for demolition.
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