Building site must be higher than the surrounding ground[Building Standards Law Of Japan]

今回の記事
It is a brief introduction of Article 19 of the Building Standards Act. “hygiene” and “safety” are stipulated for the premises of buildings.

I will tell you the most important thing first.

・Be careful of cliffs!
・Don’t let the ground be lower than the road!

Hello everyone! I am Yamaken.

Hygiene is the regulation of a part related to public (Rainwater, drainage, etc.) health.
Safety is defined as the structural stability (Measures for cliffs, etc.) as a residential area.

 




Introduction

Article 19 of the Building Standards Law regulates the hygiene and safety of the land of buildings. Based on this regulation, concrete standards are set by the Cabinet Order.

[Article 19 of the Building Standards Law (Hygiene and safety of the site)]
The building site must be higher than the adjacent road boundary and the building ground must be higher than the adjacent surrounding land. However, this does not apply if there is no hindrance to drainage within the site or if moisture protection measures are not required depending on the building’s purpose.

2 When constructing a building on a wetland or a land with a high risk of inundation, it is necessary to take necessary measures for hygiene and safety such as raising the land and improving the ground.

3 Appropriate sewers, drains or similar facilities to discharge or treat rainwater or sewage shall be installed on the building’s premises.

4 In cases where a building is likely to be damaged by a landslide, etc., it shall be necessary to install a retaining wall or take other appropriate measures for safety.

Important part of Paragraph 1, Article 19 of the Building Standards Law

① The building site must be higher than the road adjacent to the building site.
☑️

The requirement is that the site must be high, regardless of whether the road is adjacent to or not connected to the site of the building.

If the road is lower than the site, rainwater that collects on the road will flow into the site, and we have established this regulation to prevent this.

In current architectural design, it is generally impossible to design lower than the road. However, at the time when the Building Standards Law came into effect, it is thought that there was a situation where rainwater accumulated on the site.

② The ground level must be higher than the surrounding land.
☑️A ground plane is typically the location of the face where the building core (foundation) meets the soil. In this regulation, the position of the surface that contacts the soil (foundation) should be higher than that of the part that does not.
道=Lord
敷地=Site


*Image of Article 19, Paragraph 1 of the Building Standards Law

However, there are exceptions to the provisions of paragraph 1 and they do not apply to the building site in the following cases:

  • Cases where the use of the building (Usage) does not interfere with drainage or where moisture prevention is not necessary
  • ① This applies to cases where there is no hindrance to drainage and ② there is no need for moisture prevention depending on the use of the building.

Although not common, it is a method of installing a drainage mass on the site and then pumping it to the road.

Also, depending on the application of the building in ②, if moisture prevention is not necessary, it means that there is no problem with drainage even if a small amount of rainwater enters, for example, in a bicycle shed.

Important part of Paragraph 2, Article 19 of the Building Standards Law

2 When constructing a building on a wetland or a land with a high risk of inundation, it is necessary to take necessary measures for hygiene and safety such as raising the land and improving the ground.

For example, soft soil is ground improvement.Another way to improve the quality of the ground is to raise the soil and promote consolidation(consolidation settlement) , or to replace it with good soil(replacement method).

Important part of Paragraph 3, Article 19 of the Building Standards Law

3 Appropriate sewers, drains or similar facilities to discharge or treat rainwater or sewage shall be installed on the building’s premises.

It is a regulation about the treatment of rainwater and sewage.
There is no need to explain and it is a rule that should be followed.雨水と汚水の処理に関する規定ですね。

Important part of Paragraph 4, Article 19 of the Building Standards Law

4 In cases where a building is likely to be damaged by a landslide, etc., it shall be necessary to install a retaining wall or take other appropriate measures for safety.

In order to ensure the safety of residential land, if necessary, a retaining wall or something similar to a retaining wall should be installed on the site.

When constructing under a cliff, it is necessary to ensure the safety of the residential area, but in the case of a residential area where the soil is raised, there is a risk of circular slip, so it is also necessary to ensure the safety when constructing on the cliff.

Summary

This time I briefly explained Article 19 of the Japanese Building Code!

In addition, specific standards based on laws and regulations are stipulated by Cabinet Order.

This concludes the explanation.
Thank you for watching until the end.