When building a detached house, the size of the land has a direct impact on both the floor plan and overall living quality. A 50-tsubo lot (approximately 165 m²) offers generous space and is well above the average lot size for a custom-built home (38 tsubo). In this article, we explain what kind of home can be realized on a 50-tsubo lot and the key points for making the most of that space.
How large is a 50-tsubo lot, and what can you build on it?
Fifty tsubo is about 165 m², which is slightly larger than a volleyball court. However, you cannot legally build across the entire site, so understanding the building coverage ratio and floor area ratio is essential.
What are the building coverage ratio and floor area ratio?
The building coverage ratio is the percentage of the site area that can be occupied by the building footprint, and it is set between 30% and 80% depending on the zoning district. The floor area ratio sets the upper limit for total floor area. On a 50-tsubo lot with a 50% building coverage ratio, the maximum building footprint is about 82.5 m² (roughly 25 tsubo).
Housing options available on 50 tsubo
- Two-generation home: Even a fully separated layout with separate entrances and bathrooms can be achieved
- Home with a courtyard: A courtyard-house design that prioritizes natural light and openness is possible
- Single-story home: Increasingly popular in recent years for barrier-free living and lower maintenance costs
What are the three key ways to increase usable floor space?
Even within building coverage limits, you can effectively expand livable space with the following ideas.
1. Make use of a basement
In residential buildings, a basement is excluded from floor area ratio calculations if it is no more than one-third of the building's total floor area. It also offers excellent sound insulation and thermal performance, making it suitable for a home theater, storage, workspace, and other uses.
2. Add a veranda or balcony
A veranda or balcony that projects no more than 1 meter from the building's exterior wall is not included in total floor area. However, there are cases where installation is not possible if the building coverage ratio is already close to its limit, so advance confirmation is necessary.
3. Use the attic or loft
If the height is 1.4 meters or less and the area is no more than half of the floor area below, the attic or loft is not counted toward the number of stories or total floor area. This makes it highly effective as storage space.
Points to keep in mind when building a house on 50 tsubo
A larger house also brings proportionally higher utility and maintenance costs. If you include an open atrium, air-conditioning efficiency may decline, and you should also consider the possibility of unused rooms after children move out. A design that anticipates not only your current family structure but also your lifestyle 10 to 20 years from now is important.
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Frequently Asked Questions (FAQ)
Q. What size LDK home can be built on a 50-tsubo lot?
It depends on the building coverage ratio and floor area ratio, but in a typical residential area (50% building coverage ratio and 100% floor area ratio), a total floor area of about 165 m² is possible. A 4LDK to 5LDK home can be achieved without difficulty.
Q. What are the advantages of building a single-story home on 50 tsubo?
A single-story home has a simple structure, offers strong earthquake resistance, and is easier to make barrier-free. Scaffolding costs and exterior wall maintenance expenses can also be kept lower than for a two-story home.
Q. Can a basement be installed on any lot?
On land with a high groundwater level or soft ground, construction costs can rise significantly, so a ground survey is essential. There may also be restrictions depending on the district plan.
Q. Are there any tax advantages to making it a two-generation home?
If the special valuation rule for small residential land applies, the land valuation for inheritance tax purposes may be reduced by as much as 80% in some cases. You should confirm the requirements with a tax accountant.
