Roof drainage and guttering

Corrosion to cast iron guttering: 1940-50

Cast iron guttering was produced as early as 1840 and was still being used on roofs in the 1940s and 50s. These systems are now coming to the end of their expected lifespans, but may not show signs of decay. The ogee-shaped gutters were fixed to the eaves through the flat section at the back of the gutter. Over the years, successive painting can stick the gutter to the eaves and the back section corrodes away, leaving the fascia board exposed to large amounts of water. This in turn rots the fascia and then the rafter ends. From the ground it is not possible to see the corrosion and the gutter could be overlooked as a possible source of water ingress. The repairs usually entail the removal of the whole gutter and replacement of the rafter ends.

Precast concrete gutters: 1950s

The Finlock precast concrete gutter became popular in the early 1950s. These can be problematic if the gutters were not lined or if the lining has decayed. Traditionally aluminium foil and hot rubberised bitumen was used to line them. The linings can become brittle and crack, or the joints between the precast sections can open up, allowing water to cascade down the walls or spill into the fabric of the building. Temporary sealants can be applied to prevent localised problems or to coat a gutter system (products such as Acropol plus), but these will have a limited lifespan.

For longer-term solutions there are specialist companies that can reline the gutters with either a continuous extruded aluminium section and EPDM liner, or a liquid applied rubberised bitumen product with a foil reinforcing layer. Precast concrete gutter systems are still available and a range of 3 profile sections are manufactured by Connaught under the Finlock name. They also provide a relining service.