Weatherings
Lead is a durable material under normal circumstances. We only have to look at stained glass windows in many of our churches and cathedrals to appreciate its longevity. However in our modern world full of modern pollutants the lead in our church windows like the lead on our roofs is constantly under attack from slightly acidic rain water. Lead being a malleable material is also susceptible to 'creep' where its own weight can, over a period of time, cause the lead to stretch and thin. Old church windows have been found to have thicker lead at the bottom than at the top! The flashings on our roofs are exposed to rapid heating and cooling during the year and the expansion and contraction can lead to problems.
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Back gutter of a chimney being offered up.
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Bossed front apron.
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Lead comes in a range of thicknesses and stock sizes. The thicknesses are given a 'code'. Code three is the thinnest used for roofing. Code 4 is typically used for chimney sets with code 5 being used where bossing is required. In exposed areas heavier lead can be used to help resist lifting.
To finish lead weatherings it is important to use patination oil. When new lead is exposed to the elements an initial white carbonate is formed. This can wash off with rain causing unsightly streaks on roofing material. An application of patination oil will prevent this.
