If you are looking to put the gully straight out through the wall, you could let it run through the wall and straight into a hopper, or alternatively use a through wall outlet and fix it so that the gully trim runs to it and out through the wall.
Another option is to go with a vertical downpipe roof outlet. Set the gully trim to run into that and the outlet will take the water down into a connecting pipe.
Whilst we would recommend GRP Trims with a fibreglass roof (the fibreglass will bond better). If you decide to use lead or metal trims, ensure the lead or metal is clean and free from contaminants. Use G4 sealer when overlapping with the fibreglass.
It is recommended that 15mm galvanised clout nail is used or s/s staples that will sit flush with the roof.
Roof trims should be measured and cut to size with a 'snips' (to reduce dust). A dab of roofing adhesive should be applied to the batons to prevent rattling in the wind. Roof trims should then be either stapled with s/s staples of nailed using 15mm clout nails into place every 120-150mm. Where two trims have to be joined together, ensure an overlap of 50mm and apply roofing adhesive to seal.
A drip trim is placed at the lowest edge of the roof and is used to allow the water to runoff into a gutter. A raised edge trim is used to prevent the water runoff.