7-1. How to Calculate the Building Coverage Ratio and Floor-Area Ratio of Logistics Facilities
The building coverage ratio (BCR) and floor-area ratio (FAR) of a logistics facility are the most important legal regulation figures that determine "how much building area can be built" and "how much total floor area can be secured" relative to the site.
1. How to Calculate the Building Coverage Ratio
This is the ratio of the "building area (the horizontal projected area when looking at the building from directly above)" to the site area.
Building Coverage Ratio (%) = ( Building Area ÷ Site Area ) × 100
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Precautions regarding Building Area:
- If an eave or overhang protrudes more than 1m from the outer wall, the remaining portion beyond the 1m setback is added to the building area (*This is an important point when designing deep eaves for truck berths).
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Exceptions for Relaxing Building Coverage Ratio:
- If the designated building coverage ratio in the area is 80%, and the building is a "fireproof building within a fire prevention district," there is an exception that adds 10% (up to a maximum of 100% = no building coverage ratio limit, when combined with corner lot relaxations, etc.).
2. How to Calculate the Floor-Area Ratio
This is the ratio of the "total floor area (the sum of the floor areas of each story)" to the site area.
Floor-Area Ratio (%) = ( Total Floor Area ÷ Site Area ) × 100
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Restrictions based on Frontal Road:
- The upper limit for the floor-area ratio is the smaller value between the "designated floor-area ratio specified by city planning" and the value calculated by "Frontal road width × Coefficient (generally 0.6 for industrial zones)."
3. Exceptions for "Relaxation/Exclusion" of Floor-Area Ratio in Logistics Facilities
When planning a logistics warehouse, there are exceptions where equipment spaces meeting specific conditions can be excluded (not counted) from the floor-area ratio calculation (total floor area). This allows for substantially more operational floor space to be secured.
| Space Eligible for Relaxation |
Conditions / Calculation Method for Relaxation |
Merit in Logistics Facilities |
Automobile Garages / Unloading Areas
(Truck berths, driveways) |
Exclude up to 1/5 of the total floor area from the floor-area ratio calculation. |
The area of truck berths, large slopes, and rampways can be removed from the floor-area ratio limit. |
| Elevator Hoistways |
Exclude the floor area of all floors for the hoistway (shaft) portion. |
Installing many freight elevators will not squeeze the floor-area ratio. |
| Disaster Prevention Stockpile Warehouses |
Exclude up to 1/50 of the total floor area. |
Disaster prevention stockpile warehouses for BCP can be installed outside the floor-area ratio limit. |
4. Specific Calculation Example
[Estimation Conditions]
- Site Area: 10,000 ㎡
- Designated Building Coverage Ratio: 60% / Designated Floor-Area Ratio: 200%
- Truck Berth / On-site Driveway Area: 2,500 ㎡
- Building Area: 6,000 ㎡
Judging the Building Coverage Ratio
6,000 ㎡ ÷ 10,000 ㎡ × 100 = 60% (Within the designated building coverage ratio of 60%: Judgment OK)
Calculating the Floor-Area Ratio (Applying the exclusion for garages, etc.)
If the planned total floor area is 22,000 ㎡ (of which 2,500 ㎡ is for berths, etc.):
- Upper limit for allowable exclusion of berths, etc. = Total floor area 22,000 ㎡ × 1/5 = 4,400 ㎡
- Since the berth area of 2,500 ㎡ is fully eligible for exclusion, the area subject to the floor-area ratio is 22,000 ㎡ - 2,500 ㎡ = 19,500 ㎡
Calculated Floor-Area Ratio = 19,500 ㎡ ÷ 10,000 ㎡ × 100 = 195% (Within the designated floor-area ratio of 200%: Judgment OK)