Keeping the Water Out
The term chimney flashing describes the introduction of material around a chimney to stop water entering the bulding. Flashing chimneys has been pracised for centuries, lead chimney flashing being one of the longest surviving methods. A chimney leak can cause severe water damage to the interior structure of the building. Being in an exposed position, the chimney flashing needs to be of the highest quality.
Lead flashing has been proved over the years to be among the top materials for such a job. Lead sheet has characteristics that allow it to be formed to account for the undulations present with tile, slates and the like. This quality not only weathers the chimney but looks pleasing and traditional to the eye.
Chimney Flashing Demonstration Video
This video is designed to support our clients and others with clear instruction on sheet lead to chimneys, looking at the parts that make up the complete lead flashing. These include back gutter, front apron, soakers and cover flashing. All play their part in weathering the chimney.
The most common problem associated with dampness around chimneys is penetration via the the brick work / masonry. Although the lead flashing looks fine and probably is, rain water is absorbed into the stack above the flashing and percolates down through the masonry and past the 30 mm that the flashing sits into the chimney. This has become more apparent of late owing to changes of living standards and building design. Air changes within domestic dwelling have reduced, flues have been blocked off and the loft area on conventional houses is often converted into living space. This restricts the natural drying process of the chimney.
In some areas of the UK, it is standard to fit a sheet lead chimney DPC tray when constructing chimneys. The installation of such acts as a barrier to any moisture that is present above the position to which it is fitted. However on an existing chimney it is not a simply matter of installing a DPC tray, and can be costly. Faced with this problem a clear sealant can be applied to the masonry projecting from the roof (During a dry spell) The sealant is absorbed by the masonry and when dried seals the pores that allow water ingress. This job may be ongoing say every two or three years, depending on the product and severity of the weather and location.
If you can sketch it, we can fetch it...