Solar Panels And Air Con Equipment

Solar water heating panels and other air con equipment items located on top of the roof cladding effectively create an unwashed area. While in theory the rain can run down the pans the ribs do not get washed.
G12/AS2 the Acceptable Solution does not take this into account and in fact allows collectors to be directly fixed to the cladding. The COP (2.6.9.) does not.

.NZMRM COP 2.6.9 Solar collectors must not be fixed directly to metal roof cladding. The collector must be mounted so that there is provision for cleaning, washing and maintenance with a minimum of 100mm clearance between the collector and the metal roof cladding. Such cleaning must be carried out every three months in severe environments.
The mounting of any collector to create an unwashed area voids the manufacturer’s warranty. Without a minimum of 100mm clearance it is not possible to brush down the tops of the cladding ribs and to prolong the life of any metal roof.
A suspended solar collector (or air-con unit) is very likely to cause condensation underneath it which will also collect on the roof cladding. Such condensation can accumulate contaminates and if premature deterioration is to be avoided, a maintenance program is required to remove the corrosive salts and dirt that cause corrosion. The person who creates the unwashed area is responsible for any subsequent damage.

UNDERSIDE OF GUTTERS AND FASCIAS
These are totally sheltered from rain – see diagram. Small roofs sheltered by porches or atriums – see photos.

WALKWAYS
Access walkways for maintenance and gutter snow or hail boards can create an unwashed areas and so should always be made of open mesh. Timber must not be used.

PREVENTION – ALSO CALLED MAINTENANCE
Few people would buy a new car and not wash it occasionally. Maintenance of your new metal cladding is no more onerous than washing every three - 12 months (depending on location and how dirty it gets). As well as protecting it from corrosion it will also keep it looking like new. Washing by a hose in many cases is insufficient without brushing and even scrubbing.

CONCLUSIONS
Metal roof and wall cladding material, rainwater goods, garage doors, canopies, walkway covers and other applications are widely used and in some applications the only material which can realistically be used.
Areas in these applications which are not naturally washed by rainwater can suffer premature corrosion failure when exposed to various chemicals in the air, primarily salt spray particles which can be carried to most parts of New Zealand by wind.
Such premature failure is easily avoided by design to minimise unwashed areas in the first instance. Where this action is not taken then a maintenance programme for unwashed areas will improve the life as well as the appearance the cladding.