This was a gully design at the bottom of a slate roof. Built in between 2 rear outrigger extensions it was a bit of a problem for the neighbouring property and the effects snow, rain and damp may have on his home with the gully built up against back wall
The lean-to and gully timberwork was already formed, the gully which was approx' 6.5mtrs
long had a fall of 2" from the far end to the front section where an internal rainwater outlet
was to be fitted
We Installed the usual 18mm OSB3 boarding to the gully section with a kickboard fitted up
the slope of the roof, this will eventually sit beneath the slating a good 10" and help with
any significant volume of water being carried down the gully and stop it tracking back into
We then fitted the preformed wall fillet trims up against the neighbouring property wall and
installed the leadwelded outlet pipe at the front end of the gully, fixing in place. Around the
leadwelded outlet we formed several angled slopes to funnel the water towards the outlet.
This was done due to design of the gully at the outlet end rather than the grp not being able
to handle sitting water. The front edge around the outlet was due to have aluminium cladding
fitted as a final finish so only sat up an inch or so higher than the gully itself, so to avoid any
overflow of water we formed these funnels to get all the water down the outlet as fast as possible.
The next problem we had was with the nieghbouring property wall, ordinarily we would install the
usual wall fillet trim then flash over it afterwards with a lead flashing. The problem with doing it
this way was sitting snow( if deep) working its way under the flashing and behind the wall trim, causing
damp internally and the ensuing repair costs this would then create.
So we decided to install a preformed grp flashing into the wall, grinding out the mortar joint, sitting it
and tagging in place before sealing the mortar joint back up with leadmate silicone sealant. We then
bandaged the preformed flashing trim to the wall fillet trim making it one complete unit with no possibility
of water ingress into the property. The bandaging was done with activated liquid resin and fibre glass
bandage roll and set to a nice hard watertight finish. We then installed the grp system to the remainder
of the gully/kickboard: activated resin, matting, resin on top before a layer of activated topcoat was laid.
A further layer of topcoat was applied the following day after a nice sanding of the gully was complete.
We then installed the slate roof, along with the 3 velux windows, weathering slate and all lead soakers
and flashings to complete what looks and is a great looking and functional roof and rainwater gully