COP v3.0:site-practice; acceptance-materials

13.4 Acceptance Of Materials 

A visual inspection of the packs of roof or wall cladding should be made to check for damage before lifting the bundles off the transport vehicle. Insufficient dunnage under and between packs can cause permanent indentations of sheet surfaces.

Upon delivery, a check should be made that the correct quantity of material has been delivered and an inspection made for any strapping damage.

An inspection should be made where overtightening of bundle straps or load tension straps may have deformed the edges of the sheets. N.B. a 50 mm x 50 mm timber batten at the top of the bundle used in conjunction with the strapping system can avoid such damage.

When unpacking sheets they should be inspected for coating damage that may have occurred during transport due to coating fretting or pick-off.


13.4.1 Presence Of Moisture Between Sheets 

The presence of moisture should be notified immediately to the manufacturer as water damaged sheets should not be installed .

All damaged materials should be replaced and sheets exhibiting marks of mechanical damage to the profile should be rejected and the manufacturer notified.


13.4.2 Colour Match 

Precoated roof, wall cladding and accessories should be sourced from the same manufacturer to avoid any difference in colour matching, both for top coat and backer coats.


13.4.3 Storage Stain 

All metal cladding and accessories should be kept dry before installation, including during storage on the roof structure, because accelerated corrosion or staining can occur with all metals if close stacked cladding or packing becomes wet.
If zinc coated nestable profiles have become wet while closely stacked, either in transportation or storage, the formation of wet storage stain or white rust is inevitable. AZ coatings are mill coated with an acrylic passivation film to give temporary protection and minimise the possibility of product deterioration. Pre-painted sheets will also deteriorate if they remain wet as moisture can cause paint softening and sheets may exhibit paint bubbling.
Aluminium, copper, zinc and stainless steel will all be permanently stained if left wet or if stored in this condition. Translucent cladding and all metal roofing accessories with a strippable film should be protected from direct sunlight.
If moisture is present, individual sheets should be dried and then re-stacked to allow air to circulate and complete the drying process.
The extent and severity of wet storage stain is usually proportional to the length of time the sheeting has been wet.
In the case of superficial attack, exposure to the atmosphere and careful cleaning will sufficiently reduce surface imperfections, but heavier deposits can damage the sheets to the extent that they require replacement.

Where it is likely that the roof or wall cladding will be stored on site for more than one week before installation, consideration should be given to ordering waterproof packaging from the manufacturer.