The London Stonemasonry team have repaired and built hundreds of masonry and stone bay windows over the years. This post aims to help you identify and prevent a common problem we encounter with older bay windows – decay and movement caused by improper rainwater drainage from the bay roof.

A bay window roof rebuilt by London Stonemasonry

Pictured: A Victorian-style bay window with a parapet on its roof, created and installed by London Stonemasonry in Dulwich, London. For roofs with parapets, a functioning rainwater outlet is often vital for preventing water from pooling on the roof.

Maintenance tips for bay window roofs

  • If your home has a bay window, or you’re considering purchasing a property with a bay, a first step in understanding and maintaining your bay window’s roof is to perform regular inspections, especially after heavy rainfalls. Look for any signs of pooling water or leaks.
  • Keep the rainwater outlet clear. For some styles of bay windows, a functioning rainwater outlet is vital for preventing water from pooling on the roof. Make it a habit to check and clean the outlet regularly, removing any leaves, dirt, or other obstructions that might impede water flow.
  • Check the lead flashings. Lead flashings play a crucial role in sealing the gap between your bay window’s roof and the brickwork. Inspect these flashings periodically to ensure they are not loose or damaged. Old or compromised flashings can allow water to seep through, leading to structural damage over time. Victorian bay windows typically rely on a timber bressummer beam. This beam supports the brickwork above the bay window’s opening and is prone to decay if exposed to moisture, particularly from water ingress through the roof.
  • Book a professional assessment. While regular homeowner inspections can be helpful, it’s also beneficial to have your bay window and its roof assessed by professionals, especially if you notice any signs of damage or decay. Our experts at London Stonemasonry can provide a thorough evaluation and recommend specific repairs or maintenance practices to ensure the longevity of your bay window.

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