Stronger buildings needed
The Aitutaki disaster shows building standards need to be reviewed

The great extent of the damage to structures in Aitutaki from Cyclone Pat has many asking about adherence to building standards and codes and whether or not buildings complied with those standards.
The “Initial Assessment Report” done by MOIP on Aitutaki building damages dated 14 February 2010, makes reference to building standards and also features noticed about how buildings were constructed.
We quote from their report below;
“Cyclone Wind Forces
Cyclone wind forces on a building acts predominantly upwards and horizontal. A building must have structural systems, which will remain intact under these loads and transmit the wind forces to the ground through its structural members, connections and claddings without failure of these elements.
According to the Cook Island Building Code, the equivalent basic wind speed for permissible stress methods of design is 49 m/s. (approx. 180 km/hr) this corresponds to category 2 Terrain and the value of the factor B1 is 1.5 and an upwind slope of 1:10 for escarpments.
As the cyclone was upgraded from a category 2 to a category 3 when it struck the Island, with expected wind speeds in the range of 176 km/hr ( 49m/s) to 208 km/hr (57 m/s). This would be just beyond the Building Code design wind speed of 49m/s.
The severity of the wind force intensity, say at 190km/hr or 53m/s, beyond the Code design wind speed would definitely maximized the potential for fatigue failure of building structure fixings, including the undamaged buildings not assessed on the islands.
Therefore with the severity of the wind force greater than the Building Code wind force and as most buildings is not well maintained, it would not be a surprise to expect such devastating damages all throughout the villages — as indicated by the average 57% of the building populations being damaged to various degrees.
Damage to newer homes was also not immune to damages from the Cyclone Pat wind forces. It was very surprising to see a fair amount of newer buildings sustaining damages, particularly at the roof structures.
There may be a need to review the design wind speed forces, of the building Code with the likelihood of newer buildings to be designed to higher wind speeds.
Impacts on Buildings
The majority of structural damages assessed was as expected, associated with older constructions (>25 years). The older structures were primarily build of lower standard and are more likely to have deteriorated components (corrosions, rot, insect attack) leading to a reduction in strength at critical fixings (roofing/purlin, purlin/rafter and rafter/wall top plate etc).
With roof damages, the lost of flashings, basic guttering was also damaged, thus the delivering of rain water to water tanks (majority of the buildings have water tanks of -varying sizes from 2000 litres to 10,000 litres) as a substitute for drinking water will be a major concern.
Some of the damages incur on buildings were caused by detached and flying building material debris from other damage buildings. The majority of homes with out-building such as make shift cooking/storage sheds were all destroyed.
There has been witness by home owners seeing their roof structure partially being uplifted/heaving motions during the intense period of the cyclone. Therefore there is also a need during the recovery phase of the rehabilitation of buildings to inspect all buildings for structural soundness.
Not only older constructions incurred damages but some newer home also received damage more particularly at the roofing. There is concern that the building standards has not improve greatly, even with the appointment in 2008 of a building inspector on the island.
From the assessments it was clear indication that the majority of building failures was the roof structure. The failures seem to occur at the purlin and rafter connection, whereby the roofing sheeting’s were still attached to the purlin. Common indication also was that the purlin is usually fixed to the purlin by a single nail driven vertically through the rafter. A two nail-skewed driven on an angle would have been adequate.
The majority of older constructed building failures were occurring at the rafter to top plate connection. The fixings were typically two or one nail skewed driven to the side of the rafter into the top plate. The cyclone ties or No.8 wires used in the older days did not exist.
There were concerns, that the high risk of faulty electrical wiring may induce short circuits/shocks due to water (and saline) ingress especially through the socket and light points caused by the brunt of severe wind force driving through and around the exposed damaged sections of the buildings.
The electrical elements and wiring of all buildings whether damaged or undamaged prior to the power being restated should be checked thoroughly to avoid risks of short circuits or causing fire hazard to the building.” -Unquote.
Times Comment
It is interesting to note the Building Code requires compliance to withstand a category 2 cyclone. Cyclone Pat was a category 3 cyclone.
It is difficult understanding the kind of logic which says build to withstand category 2 when there are five categories of hurricane.
With climate change, we can expect more frequent but more severe hurricanes so there is a need to re-build to withstand higher velocity winds.
Houses not meeting the standards should be upgraded with government providing financial assistance.
Strong houses are important for the outer islands where the majority of people are the elderly and the young.
Following this disaster it is clear that the Aitutaki Council needs to tighten up on building construction permits and ensure proper inspections.