Storm

There is a compensatory storm damage when it has blown more than 20.8 m / sec. It is sufficient that one gust of wind has been up in this wind force.

According to an international agreement, the wind speed shall if possible be measured 10 meters above ground and be stated as the mean value over a period of approximately 10 minutes.  Sudden gusts of wind may therefore be much stronger than the wind force which is stated from the meteorologists.  It is the force of the sudden gusts which decides if we have a storm or not. Furthermore the topographic conditions, which may lead to a strong increase in the force of the wind, will also have to be brought into consideration. As examples, we can mention a narrow fiord, high mountains, katabatic wind etc.

Be aware of the fact that the stated wind force may be given in m/sec, knots or km/h.

The common minimum limit for compensatory storm damage is 20,8  m/sec (meter per second), which is equal to 41 knots or 75 kilometers per hour.

According to Beaufort wind force scale this is defined as “Severe gale”

Beaufort wind force scale (see also enclosure 17)

It will always be problematic to find out the force of the wind during the time of the damage.  Claims handler and surveyor will then have to consider how strong the wind force has been. 

There is only a limited number of measuring stations doing the wind force. Local topographic conditions may easily change the wind forces.  The most reliable information will be obtained from a weather station in the area measuring the common force of the wind, and thereafter compare the reported damage to other damages in the same area and the topography where the damage has occurred.
 
The claims handler is responsible to collect the necessary information at individual damages, but normally it will be done by the surveyor.
In order to consider a subjective deduction, there is some information which needs to be obtained.  It is mainly visible faults and defects which will affect these considerations.

Other factors which are essential to take into consideration are:

The list is not complete.  Considerations have to be made whether the claimant can be blamed for faults or weaknesses.

Due to the provisions about deductions it is in particular important to obtain information about who has built the house, e.g. builder, contractor or the owner himself. The reason for this is to get sufficient information to decide whether the owner can be blamed for faults or weaknesses, or there are reasons for recourse against others.  See also the chapter about recourse.

In previous statutory regulations, the requirements for buildings constructed in areas not defined to be exposed; were that they should withstand a wind force of up to 35 m/sec and those buildings in exposed areas should withstand a wind force of up to 40 m/sec.  Today the requirements are put in concrete terms so buildings shall be able to withstand expected wind force on that location.

It is therefore referred to the various boroughs in order to clarify the local requirements.

The table below shows the variations at some places in Norway.

The Board of Appeal in Statens Naturskadefond has decided that 20,8 m/sec will be accepted as compensatory natural disaster.