Griya Kotabaru 1938, Kotabaru — 2024. Photograph: studio photography collaborator.
Renovation & adaptive reuse
Griya Kotabaru 1938
The site and the problem
A 1930s house in a district where the street elevation is controlled. The front facade, the roof form, and the setback line could not change. The clients needed two extra bedrooms and a workspace for two people, while the permitted footprint was already all but used up.
The arithmetic closed off the easiest option. A district coverage limit of 50% on 420 m² means a maximum footprint of 210 m², and the old building already used every square metre of it. Any additional ground-floor area had to be offset, or the addition had to go upward without adding footprint.
The building stands on a plot 21 by 20 metres with a six-metre district road on the south side. The old ceiling was 4.2 metres high and the roof structure was timber — two facts that governed the entire direction of the design.
Massing study
Three alternatives were tested against a single constraint: the footprint could not grow without an offset.
Alternative A— Ditolak
Rejected. Adding a storey above the old building loads brickwork laid in lime mortar and alters the controlled roof form.
Alternative B— Terpilih
Selected. An addition to the rear preserves the street elevation, and demolishing the garage keeps the coverage figure unchanged.
Alternative C— Ditolak
Rejected. An addition on the east side closes the only remaining side that still brings light into the old living room.
Design decisions
01
The addition goes to the rear, in a deliberately different material language
The new mass uses a steel frame, plastered brick walls with no mouldings, and polycarbonate roofing over the link. There is no attempt to imitate the old profiles.
The principle has long been held in conservation work: what is new must remain readable as new, so that what is original does not lose its value.
02
The mezzanine was chosen precisely because the footprint was exhausted
For decades the 4.2-metre ceiling was simply empty volume that still had to be cooled. The workspace sits on a new steel mezzanine that stands on its own columns, puts no load on the old brick walls, and can be removed without damaging the original building.
03
The footprint offset came from demolishing the later additions
A garage and store of 54 m², built in the 1980s, were taken down. That made 64 m² of new accommodation possible while keeping the coverage figure exactly where it was.
04
The old timber joinery was removed, repaired, and refitted
Twenty-three leaves were taken off, sorted, and reworked. Four could not be saved and were replaced with new frames of a plainly simpler profile, clearly different from the originals.
05
The timber roof structure was inspected member by member before the design was fixed
Forty per cent of the rafters were replaced because of termite damage. The main trusses were still sound and were kept, with steel plates added at the joints. The inspection happened before the drawings were made, not after the work started.
Working drawings
Plans, sections, and details from the working drawing set for this project. Annotations inside the drawings stay in Indonesian: the people reading them are on site.
Regulatory compliance
| Parameter | Provision | Used |
|---|---|---|
| KDB (building coverage) | max 50% (210 m²) | 210 m² after offset |
| KLB (floor area ratio) | max 1.0 | 0.72 |
| GSB (front setback) | follows the existing district line | unchanged |
| Street elevation | may not be altered | retained, cleaned |
| Permit | PBG for the addition | processed in 11 weeks |
The provisions applied to this site in this year. Provisions differ between areas and can change. The abbreviations are the Indonesian regulatory terms and are kept as they are.
Permit processing time
11 weeks
Processing time at the authority is outside the studio’s control. We record the actual time for each project so that you have a real picture rather than a promise.
Existing condition
Construction
Dated progress photographs, in chronological order.
Built
What changed on site
Once the old plaster was stripped, two leaves of brickwork appeared, laid in a lime mortar far softer than expected. The plan to open a single 2.4-metre opening in the rear wall was cancelled and replaced with two 1.1-metre openings with new lintels. The rear elevation was redrawn within a week.
The PBG process took 11 weeks, three weeks longer than expected, because the submission had to be supplemented with documentation of the existing building’s condition.
No project runs exactly as drawn.
This was my grandmother’s house. What I was most afraid of was that it would end up looking entirely new. What I value is that the added part was deliberately made to look different, so the old house can still be read.
Credits
- Client
- A family who inherited the house from the previous generation, two of them working from home
- Structural engineer
- Independent practice, Yogyakarta
- Contractor
- Main contractor
- Photographer
- Studio photography collaborator
- Students on placement
- Two architecture students, named on the sheets they drew
Have an older building you would like assessed?
Send us the location, the plot area, and the rooms you need. We reply within two working days with an initial assessment — including if we think another practice would serve your project better.
We take on a maximum of six new design projects a year. Replies during working hours, Monday to Friday.