When the rendering was done, the house looked clean and new. However, as we are keeping the existing roof, the original concrete barge caps made it all look a little drab at roof level. We came up with a solution to encapsulate the entire edge with a timber barge board that would fix into the existing concrete roof. It seems to have done the trick. The new barge boards tie-in with the new fascias for the guttering along the eaves and all of this timber edging to the roof will be painted the same colour as the windows.
The rafters to the existing pitched roof have been extended now that the concrete gutters have been removed. This will allow the roof to extend sufficiently in front of the external wall insulation. The Intello air barrier membrane beneath the rafters is Tescon taped to the existing timber wall plate to reduce the air leakage out of the cavity head (see drawing in previous post).
We are also insulating between the rafters to provide insulation continuity between the external wall insulation and the loft insulation. The rigid insulation panels are squeezed tightly between the timbers and extend approx 0.5m above the (future) loft insulation. This means that they should also serve to provide a ventilation channel into the loft. This ventilation is necessary to remove any condensation from the cold loft space, and is often provided via proprietary ventilation channels.
New, matching roof tiles have been sourced. These will soon be fitted along with the new fascia and gutters – to be continued.
At last! The gutters that have been causing the leaks in our house, via the cavity of the wall (see earlier post), have been removed. These took some grinding – three cuts needed to get them off and flush with the wall (see orange elements in drawing below). The plan now is to extend the rafters such that the roof overhangs the new external wall insulation and so that we can fit a conventional gutter system.
In addition to them having failed, these concrete gutters were one of the most significant thermal bridges in the house. As shown in the drawing below, we are planning to wrap external wall insulation across the top of the roof and link it to the loft insulation layer. This will significantly reduce the thermal bridging from the remaining elements of the concrete gutter system.
This is a sketch of our existing concrete, or finlock gutters, shaded in blue. These systems were widely used in mid-century properties and combined to serve both as the wall plate and gutter system. Continue reading