Installers Toolbox
Choosing and installing a roof made from COLORBOND® steel is one way of protecting your reputation as a professional tradesperson.
Here's some good on the job tips and advice on getting the best out of the material, ensuring you deliver the end result that both you and your customers want.
Working with COLORBOND® steel
Care and storage
If sheets or bundles aren't being used immediately, they should be stacked neatly, clear of the ground. They should also be covered to avoid them getting wet.
A process called capillary action can lead to corrosion or a wet storage stain. If moisture gets between the sheets or under the coil wraps, it can penetrate between surfaces, causing temporary softening of the paint film – and the possibility of minor colour changes on some paint finishes.
After drying, the coating will revert to its original state – so it's important to take extreme care with the surface until it has dried and the coating hardness has returned to normal.
CORSTRIP® protective film
Many products made from COLORBOND® steel are supplied with a special polyethylene film, known as CORSTRIP® film. This protects the product during storage and handling.
The film is easily removable on installation and is plastics (4) recyclable. Check with your local council to find out whether plastics (4) can be recycled via regular kerbside pickup or through your local waste management depot.
Because sunlight can increase the film's adhesion properties, CORSTRIP® film should be removed immediately after the product is installed. (For the same reason, stored roof sheets should not be left uncovered outside).
CORSTRIP® film on coil should be removed within 12 months.
Bending and rollforming
It's recommended that the bending and rollforming of COLORBOND® steel be carried out dry.
Under normal circumstances, the CORSTRIP® film acts as an excellent 'dry lubricant'. If, however, a lubricant is needed, it should be a fully volatile branched chain hydrocarbon type liquid. (Kerosene or distillate should not be used, as they soften the paint film).
It's important to observe the recommended minimum bend radii, otherwise cracking of the paint film can occur.
These cracks may not always be visible to the naked eye, but they can still harbour dirt and, when used in external building applications, may lead to tension bend corrosion.
Fasteners and accessories
Selection of the right fasteners and accessories is crucial.
Fasteners must have a lifespan at least equal to that of the COLORBOND® steel on which they're being used. In all cases, they should comply with Australian Standard 3566.
Equally, rainwater goods and roof flashings must be of a material that is at least as durable as the roof sheeting. As an example, you should avoid using galvanised gutters with a roof made from COLORBOND® steel. (BlueScope Steel no longer recommends galvanised steel for rainwater goods, roof flashings or cappings. Ask for COLORBOND® steel by name).
Slope of roof
Properly designed and installed, traydeck profiles can be used on roofs with slopes of as little as one degree.
More traditional profiles can be used on roofs where the pitch is still low, but not as critical.
Gutters
Care should be taken to install gutters with adequate fall to avoid water ponding.
Inert catchment
Inert catchment is a term used to describe roofing that does not change the quality or nature of water as it flows across it. (In other words, virtually pure rainwater – plus any chlorides or acids absorbed from the atmosphere – flows into the gutter).
COLORBOND® steel is an inert catchment.
The use of galvanised steel guttering in combination with an inert catchment can accelerate corrosion of the guttering.
For this reason, BlueScope Steel recommends you use only COLORBOND® steel or ZINCALUME® steel for your guttering and rainwater goods.
Lead flashing
Lead flashing should not be used with COLORBOND® steel. Use soft zinc or aluminium instead.
Sealants
Neutral cure silicone rubber sealants are the only sealants recommended for use with COLORBOND® steel.
Swarf removal
During roof installation and after completion, it's very important to clean up any swarf particles and other metal scraps (such as pop rivet stems and fasteners).
If left on a roof for any extended period, these can cause rust stains – detracting from the finished appearance of the COLORBOND® steel.
Swarf should be swept or hosed off the roof at the end of each day. (Be careful when removing any swarf that's become stuck, so as not to damage the prepainted steel surface).
Ideally, the roof should be inspected about two weeks after completion, by which time rain and condensation will have caused any remaining swarf to rust.
This can then be easily seen and removed before it causes long term problems.
Cut edge protection
COLORBOND® steel has in built protection against corrosion at cut edges.
When the steel substrate is exposed by slitting, cropping, piercing or scratching, the zinc compound in the steel coating reacts with moisture in the atmosphere and builds up around the affected area. This effect is known as 'self healing'.
Brick cleaning
If brick cleaning fluids come into contact with roofing or guttering made from COLORBOND® steel they can adversely affect its paint finish and long term corrosion resistance.
In cases where the second storey of a brick dwelling sits over a roof section of the first storey, the builder should clean the brickwork before the lower level roof and guttering is installed.
