Rumah Deret Purwomartani, Kalasan — upper floor structure, 8 July 2026. Photograph: studio supervision record.
House
Rumah Deret Purwomartani
This project is under construction. Progress as of July 2026: the upper floor structure of all three units is complete, and wall and joinery work is in progress. The photographs on this page are dated construction photographs, not renderings.
The site and the problem
The developer asked for three units with identical plans so that material purchasing could be combined and the builders would not have to learn two layouts. The difficulty is that the middle plot has no open side at all — units sit against it left and right. An identical plan would produce one dark, airless unit, and that is the one that stays unsold longest.
Three plots of 8 by 20 metres each, with a six-metre estate road on the south side, a four-metre setback, and a two-storey height limit. None of those figures was the problem; the problem was the position of the middle unit.
The second constraint was budget. Small-scale developers count to the square metre, and any specification that has to be ordered specially will be struck out by them on site.
Massing study
Three alternatives were tested against one question: how does the middle unit get light and air without changing the structure that was made identical.
Alternative A— Ditolak
Rejected. Three fully identical units give the largest saving, but the middle one is dark all day and takes longest to sell.
Alternative B— Ditolak
Rejected. A gap between units gives side light, but it eats saleable area and adds two external walls per unit.
Alternative C— Terpilih
Selected. The middle unit is split by a void at the centre of the plan; the structure stays identical and the light comes from above.
Design decisions
01
One base plan, three variants of opening
Structure, stair position, pipe runs, and sanitary points are identical across all three units — that is where the saving is. What differs is only the position and size of the openings, according to which side is open.
02
The middle unit gets a void and a skylight instead of side windows
A void 1.6 metres wide cuts through the upper floor slab at the centre of the plan, closed with a skylight that has side vents. Light comes from above; warm air leaves through the sides of the skylight.
The middle unit therefore has 8 m² less floor area than the other two, and its asking price was adjusted accordingly. That was discussed openly with the developer from concept stage.
03
Specifications locked to what the local builders merchants stock
Tile sizes, aluminium window sections, light-gauge steel profiles, and paint grades were all set from what is available within a ten-kilometre radius. The working drawings name dimensions and quality grades rather than a single brand, so the developer keeps room to negotiate without changing the design.
04
The terrace is composed as one elevation, not as three houses in a row
The eaves line runs continuously, but the front plane of each unit steps 40 cm in and out. From the road the terrace reads as one long building with a rhythm, not as three copies.
05
The carport is sized for motorcycles first, cars second
At this price point, two or three motorcycles are far more certain than one car. The carport is sized to take both without eating into the veranda.
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 60% (96 m²) | 62 m² per unit |
| KLB (floor area ratio) | max 1.2 | 0.61 |
| KDH (green area) | min 20% | 28% |
| GSB (front setback) | 4 m from plot boundary | 4 m |
| Height | max 2 storeys | 2 storeys |
| Permit | PBG for three units, filed together | issued 2025, 6 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
6 weeks, issued 2025
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.
We asked for three identical units to save money. They said it was possible, but the middle one would be hard to sell, and they explained why. In the end the middle unit got a void. That was the first one to sell.
Credits
- Client
- A small-scale housing developer; their third project
- Structural engineer
- Independent practice, Yogyakarta
- Quantity surveyor
- Quantity surveyor, cost control
- Contractor
- Main contractor
- Students on placement
- Two architecture students, named on the sheets they drew
Have a plot with a similar problem? Send us a brief.
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