ᐅ Design for Extension/Renovation of a Single-Family House into a Zero Energy Building (ZEB)
Created on: 1 May 2021 15:13
G
Gudeen.
Hello,
We have been planning for a long time to extend/convert my parents’ single-family house into a two-family home, with a ground-floor unit for my parents and a unit spanning the ground and upper floors for my family with two children. Because of various restrictions related to the zoning plan and setback rules, the floor plan is unfortunately not as straightforward as it would be with a free design. However, since there are practically no available building plots here, a new build is not an option. Together with an architect, we have now created a design that does not fully comply with all details of the zoning plan but has been discussed with the building authority regarding its likelihood of approval.
Since it was quite complicated to create a suitable design and many changes have been necessary since our initial ideas, I wanted to share the result here for discussion.
The entire roof will be replaced and the ridge shifted, raising the building height and providing more space. The part added onto the garden side was originally intended to have a shed roof, but after consulting with the building authority, the gable roof must at least be indicated. At the same time, the house will be renovated to meet KfW-85 energy efficiency standards and the gas heating system will be replaced with a ground-source heat pump. The existing building is a timber frame construction with solid masonry exterior walls (built in 1989). Currently, there is a 2x2m (6.5x6.5 ft) spiral staircase in the center, which will be closed off. The extension is planned as a timber frame structure, provided the current wood prices don’t disrupt the plan.
We are still uncertain about the heating method for the upper floor. The new rooms will have underfloor heating, but I am unsure if the structure can support it in the existing upper-floor rooms (the design has not yet been reviewed by a structural engineer). Alternatively, we could consider heating the wall across the entire upper floor using a wall heating system.
To provide enough natural light to the kitchen in the extension, we plan to leave the air space above the kitchen open and install a roof window. The bathroom upstairs and possibly the bedroom will have double casement windows. I suspect the structural support for the parents’ bedroom above the kitchen could be a problem (since there are hardly any load-bearing walls underneath), although the architect has not yet mentioned this. What might be the best solution without closing off the mentioned air space above the kitchen?
Zoning Plan / Restrictions
Plot size: approx. 750m² (8,073 sq ft)
Slope: No
Site coverage ratio (Grundflächenzahl): 0.4
Floor area ratio (Geschossflächenzahl): 0.6
Building envelope, building line and boundary: 5m (16.5 ft) to street (excluding carport), 3m (10 ft) to neighboring plots
Max. wall height at boundary build: 3m (10 ft)
Number of parking spaces: 2
Number of floors: 1.5
Roof style: gable roof
Orientation: NE-SW
Additional requirements: On the NW side is the driveway to the rear plot. There are existing easements granted by the neighbor, so the driveway can only be partially counted as a setback area.
Client Requirements
Style, roof shape, building type:
No basement, ground floor and upper floor, attic not developed as living space
Number and age of occupants:
1st unit: 2 persons >60 years old,
2nd unit: 2 adults (35 years) and 2 children (6/8 years)
Room requirements on ground and upper floors:
Ground floor: one fully accessible unit suitable for elderly occupants with a guest room; living room, kitchen, and garden access/terrace for the second unit
Upper floor: 2 children’s rooms, bedroom, bathroom, and utility room
Office: a workspace in a quiet room (semi-separated part of the bedroom) that will be used partly as a home office
Guest stays per year: rare, so not important in the planning, but the ground-floor unit must have a guest room
Additional wishes/particulars/daily routine, including reasons why some features are wanted or not:
A highlight of the existing building is the large conservatory, which makes the house bright and open. This should be preserved, and the new rooms should also have large windows facing the garden.
An open exposed wooden beam ceiling is valued, creating a higher spatial impression.
The garden should not be strictly divided (no fence) but should still provide some privacy.
House Design
By whom: architect, with some modifications by us
What do you like most? Why? Optimal use of space within the setback rules without taking too much garden area, large windows/sliding doors.
What do you like less? Why? Some rooms are very small (e.g., technical room), which cannot be changed due to the existing building. The living room in the new unit might feel small and cramped.
Estimated cost according to architect/planner: 450,000
Preferred heating technology: ground-source heat pump
If you had to give up anything, which details/finishes
- Can you live without: double casement window in the bedroom
- Cannot do without: adequate daylight in the kitchens, large windows in living rooms, open wooden beam ceiling on the ground floor
Why is the design the way it is now? For example
Our and the architect’s attempt to accommodate all wishes without violating setback rules and zoning plan requirements.
Both units should be clearly separate but maintain the character of the house and not look like an appended box.
What is the most important/basic question about the floor plan in 130 characters?
What have we overlooked? We had to make many compromises during planning and would like to know if we are saving too much somewhere, risking regrets later, or if more could be made out of the available space.
We have been planning for a long time to extend/convert my parents’ single-family house into a two-family home, with a ground-floor unit for my parents and a unit spanning the ground and upper floors for my family with two children. Because of various restrictions related to the zoning plan and setback rules, the floor plan is unfortunately not as straightforward as it would be with a free design. However, since there are practically no available building plots here, a new build is not an option. Together with an architect, we have now created a design that does not fully comply with all details of the zoning plan but has been discussed with the building authority regarding its likelihood of approval.
Since it was quite complicated to create a suitable design and many changes have been necessary since our initial ideas, I wanted to share the result here for discussion.
The entire roof will be replaced and the ridge shifted, raising the building height and providing more space. The part added onto the garden side was originally intended to have a shed roof, but after consulting with the building authority, the gable roof must at least be indicated. At the same time, the house will be renovated to meet KfW-85 energy efficiency standards and the gas heating system will be replaced with a ground-source heat pump. The existing building is a timber frame construction with solid masonry exterior walls (built in 1989). Currently, there is a 2x2m (6.5x6.5 ft) spiral staircase in the center, which will be closed off. The extension is planned as a timber frame structure, provided the current wood prices don’t disrupt the plan.
We are still uncertain about the heating method for the upper floor. The new rooms will have underfloor heating, but I am unsure if the structure can support it in the existing upper-floor rooms (the design has not yet been reviewed by a structural engineer). Alternatively, we could consider heating the wall across the entire upper floor using a wall heating system.
To provide enough natural light to the kitchen in the extension, we plan to leave the air space above the kitchen open and install a roof window. The bathroom upstairs and possibly the bedroom will have double casement windows. I suspect the structural support for the parents’ bedroom above the kitchen could be a problem (since there are hardly any load-bearing walls underneath), although the architect has not yet mentioned this. What might be the best solution without closing off the mentioned air space above the kitchen?
Zoning Plan / Restrictions
Plot size: approx. 750m² (8,073 sq ft)
Slope: No
Site coverage ratio (Grundflächenzahl): 0.4
Floor area ratio (Geschossflächenzahl): 0.6
Building envelope, building line and boundary: 5m (16.5 ft) to street (excluding carport), 3m (10 ft) to neighboring plots
Max. wall height at boundary build: 3m (10 ft)
Number of parking spaces: 2
Number of floors: 1.5
Roof style: gable roof
Orientation: NE-SW
Additional requirements: On the NW side is the driveway to the rear plot. There are existing easements granted by the neighbor, so the driveway can only be partially counted as a setback area.
Client Requirements
Style, roof shape, building type:
No basement, ground floor and upper floor, attic not developed as living space
Number and age of occupants:
1st unit: 2 persons >60 years old,
2nd unit: 2 adults (35 years) and 2 children (6/8 years)
Room requirements on ground and upper floors:
Ground floor: one fully accessible unit suitable for elderly occupants with a guest room; living room, kitchen, and garden access/terrace for the second unit
Upper floor: 2 children’s rooms, bedroom, bathroom, and utility room
Office: a workspace in a quiet room (semi-separated part of the bedroom) that will be used partly as a home office
Guest stays per year: rare, so not important in the planning, but the ground-floor unit must have a guest room
Additional wishes/particulars/daily routine, including reasons why some features are wanted or not:
A highlight of the existing building is the large conservatory, which makes the house bright and open. This should be preserved, and the new rooms should also have large windows facing the garden.
An open exposed wooden beam ceiling is valued, creating a higher spatial impression.
The garden should not be strictly divided (no fence) but should still provide some privacy.
House Design
By whom: architect, with some modifications by us
What do you like most? Why? Optimal use of space within the setback rules without taking too much garden area, large windows/sliding doors.
What do you like less? Why? Some rooms are very small (e.g., technical room), which cannot be changed due to the existing building. The living room in the new unit might feel small and cramped.
Estimated cost according to architect/planner: 450,000
Preferred heating technology: ground-source heat pump
If you had to give up anything, which details/finishes
- Can you live without: double casement window in the bedroom
- Cannot do without: adequate daylight in the kitchens, large windows in living rooms, open wooden beam ceiling on the ground floor
Why is the design the way it is now? For example
Our and the architect’s attempt to accommodate all wishes without violating setback rules and zoning plan requirements.
Both units should be clearly separate but maintain the character of the house and not look like an appended box.
What is the most important/basic question about the floor plan in 130 characters?
What have we overlooked? We had to make many compromises during planning and would like to know if we are saving too much somewhere, risking regrets later, or if more could be made out of the available space.
haydee schrieb:
Why don’t you use the “parents” section and renovate your parents’ half to be senior-friendly? That was our first idea as well, but unfortunately the space on that side is very limited. Due to building easements, construction cannot reach the property boundary, and the north side is the “ugly” side of the house: no sun, a road, a driveway to the neighboring property, a large/tall neighboring house, and a very loud heat pump directly across the street. Because of this, no one wants large windows or living/bedrooms on that side.
Considering my parents’ “must-have” of large windows in the kitchen, living room, and bedroom, as well as a guest room, it is difficult to accommodate this on the ground floor there.
Since my parents really like the conservatory and the current ground floor setup, it’s easier for them to keep that part. With the additional upper floor, we have a bit more flexibility in the design.
I find the typical half-synoptic renovation plans much easier to overview. Besides, the new facade design and window layout alone dispel the 1980s style charm :-(
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Unfortunately, I don’t have semi-synoptic plans.
I’ve attached a photo of the old facade.
After the renovation, the facade is supposed to more closely resemble the original condition, but without the overgrowing ivy.
However, the mullioned windows have to be removed due to insulation values and costs.
11ant schrieb:Are you referring to the wooden cladding on the gable in the drawings? That was just a suggestion from the planner and won’t be implemented.
By the way, the new facade design / window arrangement alone removes the 80s charm :-(
I’ve attached a photo of the old facade.
After the renovation, the facade is supposed to more closely resemble the original condition, but without the overgrowing ivy.
However, the mullioned windows have to be removed due to insulation values and costs.
I have tried out several options to redesign the ground floor.
Attached are 3 versions (plus a sketch showing how it might affect the upper floor).
However, I’m not sure if any of these are actually an improvement over the original design, or in which direction it makes sense to develop further.
One downside common to all versions is that the floor plan would be 1.25 m (4.1 ft) longer towards the southwest, which would move the terrace to the southeast.
Together, the ground floor and upper floor would be about 13 m² (140 sq ft) larger (which might increase costs accordingly).
Also, while the living space becomes more open and pleasant, there is sometimes a lack of storage space (smaller pantry/wardrobe) and the kitchen would no longer have a direct window.
Do you have any opinions on which design points in the right direction? Or are all of them more of a step backward compared to the original design?
Attached are 3 versions (plus a sketch showing how it might affect the upper floor).
However, I’m not sure if any of these are actually an improvement over the original design, or in which direction it makes sense to develop further.
One downside common to all versions is that the floor plan would be 1.25 m (4.1 ft) longer towards the southwest, which would move the terrace to the southeast.
Together, the ground floor and upper floor would be about 13 m² (140 sq ft) larger (which might increase costs accordingly).
Also, while the living space becomes more open and pleasant, there is sometimes a lack of storage space (smaller pantry/wardrobe) and the kitchen would no longer have a direct window.
Do you have any opinions on which design points in the right direction? Or are all of them more of a step backward compared to the original design?
Not really better.
Upper floor bedroom is a walk-through room
Play area is nothing but leftover space
Ground floor is your part
You need a staircase somehow
Parents' area still has too many corners
Strange extension serves as a hallway with a small cat table
Just swap the areas. The extension could get a conservatory again.
Upper floor bedroom is a walk-through room
Play area is nothing but leftover space
Ground floor is your part
You need a staircase somehow
Parents' area still has too many corners
Strange extension serves as a hallway with a small cat table
Just swap the areas. The extension could get a conservatory again.
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