Both the traditional Danelaw mortared type and the Dry Fix Bonding Gutter design work to the minimum recommended pitch of the slates or tiles being used with them.
This depends on the situation. If the external roof covering is at the same height on either side of the Dry Fix Bonding Gutter, then the central upstand should be cut down at an angle to allow the ridge tile to pass over the joint in the roof.
If the external roof covering is higher on one side of the Dry Fix Bonding Gutter, e.g. tiles on one side, slates on the other or flat tiles on one side and profiled tiles on the other, then the ridge tile cannot be carried over the joint in the roof. In this case the central upstand should be mitre cut on both sides of the roof so that the ridge tiles can butt against it.
In both situations, a saddle should be formed over the joint. This is most easily achieved using a good quality flexible, fully adhesive flashing product such as Fast Flash.
Unsealed overlaps such as this should lap by a minimum of 150mm when measured vertically. This converts to 350mm at this low pitch.
The design of the product when fitted on top of the tile or slate battens will cause this effect. It acts in the same way as a swept verge and encourages the water to run away from the roof joint.
Whether using slates, plain tiles or interlocking tiles, the first course at eaves should be the full tile or larger slate cut.
If this is not desirable at low pitches, then Dry Fix Bonding Gutter may be installed with the side flange ribs at the same height or lower than the top surface of the roof battens, providing that it is adequately supported.
No, this is not necessary. Where the roof is in the same plane either side of the roof joint, the wind loading is not increased in the same way that it is at the eaves, verge, valleys and ridge.
The slates or tiles should be bedded on either a roof mix mortar or a low shrink, high quality external grade sealant taking care not to use excessive amounts that will spread out and block the side water channels. This is the first line of defence against rainwater and can assist in securing smaller cuts of slate or tile.
The side water channels are designed as a secondary line of defence should water enter the roof covering at this point.