7. Protection against powdery snow

Infiltration of powdery snow into attic space

As with all discontinuous roofing systems, clay tile roofs are not impervious to powdery snow, dust or soot.

The phenomenon of powdery snow penetrating attic spaces is independent of the altitude of the building. It results from the combination of a snow event consisting of relatively fine crystals, combined with wind of sufficient intensity to infiltrate the snow through tile interlockings or overlaps, or through singular roofing points such as ventilated ridges or cat flaps. The occurrence of this phenomenon, in terms of both regional delimitation and return period, has not been shown to be of such a magnitude as to cause a loss that all buildings would need to be protected against it.

The DTUs for clay tile roofing stipulate the use of a roof...