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.
Roof Laying Procedure
Wall Laying Procedure
Fixing to Steel Roofing
12 x 35mm or TS M6 x 50mm* self drilling and tapping screw with neoprene washer
Fixing to Timber Roofing
12 x 50mm or TS M6 x 50mm Type 17 hex head screw with neoprene washer
Fixing to Steel Walling
10 x 16mm self drilling and tapping screw with neoprene washer
Fixing to Timber Walling
10 x 25mm Type 17 hex head screw with neoprene washer
*When 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.
Roofing - Three Fastener Location
Roofing - Five Fastener Location
End Supports and End Laps
Walling - Three Fastener Location
Walling - Five Fastener Location
End Supports and End Laps
Using CGI Corrugated
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/al and pre-painted steel should not be used in 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/al. Check with Stratco before using in these areas.
The best way of reducing corrosion is to keep incompatible metals apart. Zinc/al and pre-painted steel cannot be used with lead, copper and monel. Galvanised steel and pure zinc material can be used with zinc/al, but you must avoid water run-off from zinc/al 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/al 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.
The performance of CGI over time depends on its correct application and maintenance. Maintenance should be performed as often as is required to remove any dirt, salt and pollutants. Where CGI is used in severely corrosive environments, cleaning should be performed more often. It is important that screws have the same life expectancy as the CGI cladding you have specified.
Packs of CGI should always be kept dry and stored above ground level while on site. If the sheets have become wet, they should be separated, wiped and placed in the open to dry.
Refer to the Stratco Selection, Use and Maintenance brochure, for more detailed information about the correct use and maintenance of this product.