A bonding gutter is a detail, that weathers the vertical join between two different roof coverings. For example, between a double lapped plain tile and say a single lapped large interlocking tile. The bonding gutter is made using preformed polymer based products, traditional lead work or more modern lead replacement flashings.
If the Homeowner wants to replace their roof tiles, a bonding gutter is required to weather the join between the existing tiles on the neighbouring properties.
Eaves felt is installed at the lowest part of the roof. This then hangs over the guttering and prevents any water seeping past the roof tile into the loft. The eaves are the roofing felt that overlaps the roof and into the guttering. Instead of felt, these days a more rigid protection system known as an eaves tray is usually specified in conjunction with a replacement uPVC roofline system. This can be instead of a timber fascia and soffit boards. The modern eaves tray is made from plastic so will effectively never rot. This makes a sensible replacement for damaged or worn out felt.
Sometimes two different tiles meet at a join but they do not interlock with each other. This creates a gap in the tiles in which water can enter the loft space. It is important that a bonding gutter be used at this point to collect and drain away any water.
It is common to see a cement bedded covering over the joint where the two tiles meet. However, this is rarely adequate or successful. The integrity of the joint relies on the cement bedding, so even if it is waterproof to start with, this will inevitably start to leak as soon as any small crack appears in the cement.
Replacing the eaves (felt/tray) requires height access equipment to the roof, then removing the first course of roof tiles. The old eaves felt is cut away a few inches above the fascia, then an eaves tray can be slid under the existing roofing felt. We make sure it overlaps into the guttering, and is then secured into place with nails into the rafters. If your eaves felt needs to be replaced, there is a high probability that the fascia boards will have suffered too, so this would be a good time to replace the roofline products too (fascia, soffit and bargeboard). The eaves trays are normally replaced during a replacement of the roofline products. You will need to remove at least the first row of roof tiles and cut back the existing felt to expose the roofing timber required for fitting the new fascia. You can then install an eaves vent strip to the fascia board to help stop condensation and damp from occurring in the loft space.