The Building Water insulation is applied in order to protect the building foundations and basement walls again the harmful effects of underground water and the effects of sulfate on floors withouth underground water. The usable life of buildings with basement building is very long. Mostly buildings with weak foundations are destroyed during earthquakes. High performance Lineflex EPDM membrane protects the buildings' foundation agains water and achemicals such as salt, acid and alkali in the soil. The building application is performed by covering the building foundations and the side walls in contact with the soil with Lineflex EPDM membrane.