Quick clay is marine clay that can lose much of its strength when its structure is overloaded or disturbed. A home buyer should distinguish a mapped quick-clay hazard zone, the possibility of marine clay and a specific assessment of stability at the property.
What does the area marked on the map mean?
NVE hazard zones identify mapped areas with a potential risk of larger quick-clay landslides. The zones are based on geological mapping, topography and geotechnical assessment. They can include information about hazard level, consequence and risk.
A map intersection means that the property lies in or touches an area that needs particular attention in land-use planning, development or ground work. It does not mean that the building is damaged or that a landslide will occur.
Look for investigations of the property
The mapping is not complete. NVE explains that the dataset may contain errors and that quick clay may also exist outside mapped zones. A mapped zone is not a geotechnical assessment of the individual property.
The absence of a finding in a Budsjekk App report therefore cannot prove that the site contains no quick clay. Consider the result together with the terrain, previous ground work, available site investigations and municipal records.
How to examine a finding
If the property intersects a zone, confirm which part of the parcel is affected and look for geotechnical reports in the municipal planning and building archive. If the property is merely near a zone, the map only shows the distance to the mapped area.
For an existing home, relevant records can differ from those needed for a proposed development. Look for information about foundations, retaining walls, excavation, filling and observed settlement.
Questions before bidding
- Does the property boundary intersect the mapped zone?
- Are site investigations available in municipal records?
- Has excavation, filling or terrain work been carried out?
- Have cracks or settlement been assessed by an appropriate professional?
The map is a starting point for further review. A geotechnical professional must perform a specific assessment when the regulations, proposed work or local conditions require it.
What to check
- Confirm whether the property boundary actually intersects a mapped hazard zone.
- Look for geotechnical reports in municipal planning and building-case archives.
- Ask the municipality about documentation requirements for proposed ground or building work.
- Ask a geotechnical professional to assess the matter when the project or local conditions make map information insufficient.