Drawing for the worst snow day

Entry 013 · Essay · 2 Oct 2026 · 7 min · By Lena Caduff, partner

Why our roofs start from the heaviest winter on record.

Every roof we draw begins with one number: the deepest snow ever measured on that slope. Not the average, and not the code minimum. We find the worst day in the records and design for it.

The code is a floor, not a target

Swiss snow-load codes are good, but they are written for a whole region. A single slope can catch twice the drift of the village below it. So we go up in February, measure, and talk to whoever has cleared that roof for the last forty years.

Keep the snow, don't fight it

A roof that sheds snow drops it onto paths, doors and parked cars. A roof built to hold it gets a free blanket of insulation for four months. The Engadin library carries 900 mm of snow on purpose.

What it costs

Heavier roofs mean deeper beams and more timber, about 6% more on structure. In exchange, nothing slides off, nothing breaks, and the heating bill drops every winter the building stands.

We would rather over-build once than repair every spring.