Do You Know What Is Water Tightness of Building Maintenance Systems?

What is the water tightness of building maintenance systems?

The water tightness of the building maintenance systems refers to the ability of the roof or wall system to prevent rainwater 

from penetrating into the enclosure system or indoors under the simultaneous action of wind and rain when the external windows 

are normally closed.

At the same time, it also refers to the ability of the vapor barrier layer in the roof wall system except for the window to block the 

penetration of water vapor into the interior of the enclosure system, especially the interior of the thermal insulation materials.