Does a flood zone prevent buying?

No, but it's a risk worth pricing in and confirming with your insurer.

What does 1/100a mean?

A flood occurring on average once in a hundred years — a significant hazard class.

Where does the flood data come from?

From the open flood-map data of SYKE and the ELY centres.

Flood risk: what a flood-hazard zone means for a buyer

By Lumi · Updated: Jun 16, 2026, 12:00 AM

A flood-hazard zone affects insurance, repairs and resale. How to read SYKE's flood maps before buying a home.

Important: A flood zone can affect insurance, basement spaces and resale — confirm your insurance terms.

Some Finnish homes sit in a flood-hazard zone near the sea or a watercourse. It doesn't prevent living there, but it's worth knowing: it affects risk, insurance and value.

What the zones mean

SYKE maps flood hazard by return period. 1/100a means a flood occurring on average once in a hundred years (significant); 1/250a is rarer. Coastal and watercourse floods are distinguished.

Why it matters

Flood risk can affect insurance terms, the use of basement and ground-floor spaces, and resale. In new developments the risk is addressed in planning.

How to check

Lumi shows the address's flood-hazard status from SYKE's open data. Also ask the housing company whether flood protection has been done.

Frequently asked questions

Does a flood zone prevent buying?: No, but it's a risk worth pricing in and confirming with your insurer.
What does 1/100a mean?: A flood occurring on average once in a hundred years — a significant hazard class.
Where does the flood data come from?: From the open flood-map data of SYKE and the ELY centres.

Sources

SYKE — tulvakartat