Fixing Recommendations

CGI sheets should be laid into the prevailing wind and sit neatly on the preceding roof sheet, with a side lap of 1.5 corrugations, as shown in the laying procedure below. They should be fixed within the recommended support spacings. Avoid ‘stretching’ the width of the sheet when installing, as this could allow wind and rain to enter. Side lap fixing is recommended to maintain a weather proof seal and to secure the overlap especially when the roof is walked on occasionally. This is best done with either 8 x 12mm self drilling stitching screws or a 3.2mm blind rivet (rivets should be sealed to prevent water penetration). It is recommended side lap fasteners are secured mid-span, when spans exceed 900mm for roofing and 1200mm for walling. On roofing, at the end of the sheets, the valleys of each corrugation should be turned up at crest of the roof and down into the gutter using a turn up/down tool.

Corrugated (CGI) Fastener Selection
	ROOFING Crest fixing	WALLING Pan fixing
Fixing to Steel Self drilling and tapping screw with neoprene washer	12 x 35mm or TS M6 x 50mm*	10 x 16mm
Fixing to Timber Type 17 hex head screw with neoprene washer	12 x 50mm or TS M6 x 50mm	10 x 25mm
Laying procedure
*If fixing to 0.55mm thick roof battens, crest fix with M6 x 50mm TS self drilling screws with neoprene washers. Indicated spans will still apply.

Walking on CGI

When walking on CGI roofing, it is recommended you walk over the purlins to avoid any damage. Wear flat, rubber soled shoes and walk flat footed, spreading your weight over as many corrugations as possible. For carport and verandah applications, crawl boards should be used to avoid damage during installation and maintenance.

Using CGI

Stratco CGI will have a long, useful life if used according to Stratco specifications. While roofing materials in outer urban and rural areas may have a life-span in excess of 30 years, this can reduce to only a few years in coastal and industrial environments.

Zinc/alum and pre-painted steel should not be used in very aggressive areas such as near swimming pools and spas. It is important that dirt, soil, compost, paving sand, or other materials which retain moisture are not placed against steel sheeting. Concrete should not be poured against zinc/alum material. Check with Stratco before using in these severe environments.

Incompatible Metals

The best way of reducing corrosion is to keep incompatible metals apart. Zinc/alum and prepainted steel cannot be used with lead, copper and monel. Galvanised steel and pure zinc material can be used with zinc/alum, but you must avoid water run-off from zinc/alum onto galvanised material. Fixings such as rivets and self-drilling screws must be compatible with the material they are fixing.

Handling and Cutting of CGI

For safety, wear gloves when handling CGI. Ensure your hands or gloves are clean, especially when handling zinc/alum which can mark. Use a coloured pencil for marking steel, as lead or black pencils contain graphite which promotes rusting. CGI is best cut using tin snips, but for larger cuts it may be necessary to use a power saw with a steel cutting blade or a power nibbler. Avoid using abrasive discs as they can cause burred edges and coating damage. Where possible cut sheets on the ground, and always clean off any swarf and metal filings progressively during the installation. Dispose of off-cuts carefully.

Insulation and Sealants

The use of blanket insulation is recommended in domestic roofing to assist in temperature, condensation and sound control. CGI can be used with an insulating blanket up to 55mm thick. Increased thicknesses require longer fasteners and greater care when installing. When choosing a silicone sealant, ensure it is suitable for roofing and guttering use and of a non-acetic, amine free, neutral cure type. Sealants that smell of ammonia, vinegar or lemons are not usually suitable.