(For construction companies) Points to note when selecting carport products and deciding on installation locations
Updated: July 2026, 7
We've been hearing more and more from construction companies that install carports that "recently, we've been receiving more and more requests from homeowners asking us to properly handle the building permit application process."
To properly submit a building permit application, it is important to consider regulations such as the Building Standards Act when selecting a carport product and deciding on its installation location.
If you don't consider regulations when choosing products and deciding on installation locations, you might encounter problems like these...
- After submitting the building permit application, it was discovered that the design violated regulations, requiring a change in the product.
- The planned installation proved difficult, leading to changes in the plan and requiring the procedures to be redone.
- It turned out that installing a carport was simply not possible in the first place.
Many building regulations are unique to each local government, making it extremely difficult to completely eliminate these kinds of problems and rework.
However, by understanding the basic points and planning ahead, you can significantly reduce the number of problems.
Our company handles dozens of building permit applications every month.
Based on our extensive experience in handling applications, we will share some key points with you.
*The final decision rests with the local building official or designated inspection agency.
Since decisions may vary from region to region, please use this website as a reference for common examples and points to consider.
Key points for choosing a carport
① Performance, size, and price
This is where the homeowner's preferences most come into play, including wind resistance, snow load capacity, the number of vehicles it can accommodate, roof performance (such as preventing sun damage to cars), design, and budget.
Taking into account the regulations from ② onward, it is important to choose products that best suit the client's needs.
② Restrictions on area and size (impact on building coverage ratio, floor area ratio, daylighting requirements, etc.)
You need to consider the maximum building coverage ratio and floor area ratio for the site, as well as the size of any existing buildings, to determine what size and area of carport can be installed.
Main relaxation requirements:
Upper limit on building coverage ratio (building area):
In the case of a carport with a high degree of openness, the 1 meter on each end can be excluded from the building area calculation.
Example: If a 3m x 5m carport has high openness on all sides,
With a building area of 1m x 3m (3m²), the building coverage ratio can be calculated as OK. (Excluding the 1m at both ends)
Upper limit on floor area ratio (total floor area):
If the intended use is a garage, 1/5 of the total floor area, including other buildings, can be excluded from the calculation.
Example: If the total floor area of the house is 75 m² and the floor area of the carport is 25 m² (5 m x 5 m),
One-fifth of the total floor area (100 m²), or 20 m², will be excluded from the calculation.
(As a result, only 5 square meters of the carport's floor area is included in the calculation.)
Carports are products that are often eligible for relaxed requirements regarding both building coverage ratio and floor area ratio, and they can often be used with ample room to comply with area regulations.
On the other hand, one aspect that is often overlooked is the "impact on the requirements for existing homes."
Often overlooked impact on existing housing requirements:
Lighting requirements:
Living spaces (rooms where people spend time, such as living rooms and private rooms) must have openings (windows) that allow a certain amount of natural light.
→When installing a carport in front of a living room window, it must be kept at a certain distance from the window.
It may not meet the required lighting conditions.
(In order to keep a certain distance from the windows, the size of the carport itself may need to be reduced.)
Impact of mitigation through exterior wall setbacks and securing open spaces (such as road setback regulations):
In road setback regulations, there are cases where relaxation measures are applied on the premise that "there are no other buildings between the road and the house."
If there are relaxations in place due to the "securing of open space," building a carport on that open space may void the relaxation and result in the existing house failing to meet the requirements.
→By choosing a carport that is relatively small, it may be possible to secure sufficient open space.
When choosing a carport, you need to consider how it will affect the requirements of your existing home.
③ Material restrictions (especially for products exceeding 30 m² / fire-prevention and semi-fire-prevention zones)
The material used for the carport must comply with the regulations of the area where it will be installed.
Carports from various manufacturers (LIXIL, Sankyo Aluminum, YKKAP, etc.) generally comply with common regulations, but there are still cases where caution is necessary.
Cases requiring special attention:
- Products exceeding 30 square meters
⇒Polycarbonate sheets, commonly used as roofing material, cannot be used. (Aluminum alloy or heat-shielding FRP sheets are required.) - In the case of installation in fire prevention or semi-fire prevention zones.
⇒In these areas, if all buildings on the site are "fire-resistant buildings, etc." or "semi-fire-resistant buildings, etc.", the building coverage ratio will be relaxed.
If a carport does not fall under the categories of "fire-resistant building, etc." or "semi-fire-resistant building, etc.", it may not be eligible for the relaxation of building coverage ratio regulations, and as a result, it may not be possible to install it.
④ Impact of options and customization (screen installation, size adjustment, column position changes, etc.)
As mentioned above, carports are subject to specific mitigation measures and regulations.
If you use the standard products from each manufacturer, they are basically designed to fully utilize the relaxation measures and comply with regulations.
On the other hand, adding options or customizations to meet the client's requests may result in some relaxation measures being excluded or the building failing to meet regulations.
*For example, changing the position of a column may make it impossible to meet the requirement of "high openness," which could lead to exceeding the building coverage ratio.
Options and customizations should be considered in light of their impact on mitigation measures.
Key points for deciding on the location of a carport
① Distance from the property line / setback restrictions
According to the provisions of the Civil Code, as a general rule, carports must be installed at a distance of 50 cm from the property line of the adjacent property.
If it's absolutely impossible to maintain a 50cm distance, you should take steps such as obtaining your neighbor's agreement beforehand.
Also, make sure the installation location does not violate any of the various setback regulations (road setback regulations, north-side setback regulations).
② Physical interference with the foundation (piping, block walls, house foundations, outdoor units, etc.)
When we receive a construction plan from a contractor, a common issue is that they haven't considered the size of the carport foundation.
The size of a carport foundation is specified by the manufacturer or industry association (Japan Exterior Construction Association).
Taking the size of the foundation into consideration, install the carport in a location where it will not come into contact with block walls, house foundations, or other installed structures (such as outdoor air conditioning units).
Also, check the existing piping (sewer pipes, rainwater pipes, etc.) beforehand and ensure that the foundation is installed in a location that does not interfere with the piping.
③ Regulations on existing houses (especially regarding daylighting requirements)
As mentioned earlier in "Points to consider when choosing a carport," installing a carport can sometimes affect the requirements of an existing house.
When deciding on the installation location, take into account the requirements of the existing house, such as lighting requirements, setback from the exterior wall, and securing open space.
④ Other various regulations (especially those unique to local governments)
In some cases, there may be regulations specific to the local government or region (such as various agreements).
Before deciding on the product and installation location, make sure to identify as many regulations as possible in advance, including any specific regulations, by consulting with local government offices.
It's best to consult a professional!
Up to this point, we have shared the points to consider when selecting a carport product and deciding on its installation location.
On the other hand, it would be a significant burden for the construction company to investigate all of these points themselves beforehand.
For a smoother carport installation process, we recommend entrusting the job to our expert team.
Support provided by a team with extensive experience in building permit applications
Building permit applications are one of our specialities.
Our building confirmation application teams in our Tokyo, Nagoya, and Osaka branches work together to ensure that applications are processed quickly.
Fast Response
The application for building confirmation is a procedure that must be completed before construction begins. If the application is delayed, the installation of the carport will also be delayed.
Therefore, a sense of speed is important.
We can respond quickly with our specialized teams located at locations across the country.
In addition, we handle everything from preparing the documents to submitting the application, so you can focus on your own business.
