Bay window movement solved with a rebuild, London

The new bay window created and built by London Stonemasonry

Pictured: The new bay window created and built by London Stonemasonry

London Stonemasonry recently rebuilt a stone bay window that had been built incorrectly by another company, on Friern Road, Dulwich, London, SE22. By working with a timber sash window company we were able to provide an all-in-one service for the homeowner.

Before and after photo of the replaced bay window

Bay window before restorationA stone bay window we assessed for an insurance claim

Pictured: Before and after photo of the bay window, Friern Road, Dulwich, London, SE22.

The challenge

The bay window had been rebuilt recently – by another company – as there was movement in the structure. However, after the rebuild, the bay structure was still moving. The homeowner was unhappy and their builder called us in to take a look.

We visited the property with our structural engineer and it was clear that the repair works were insufficient. For example, there was movement in the stone sills under the first floor window.

After producing a structural report and assessment of works needed, we sent the information to the homeowner’s insurers.

We reported that the bay window was in need of a full rebuild with new stone elements alongside a new foundation and brickwork to prevent movement in the future. Victorian bay windows were often built on little or no foundation and this was the main cause of the movement.

Also, Victorian bays often rely on a timber bressummer beam which supports the brickwork above the opening inside the bay window. These bressummers often decay over time, especially if there are issues with water ingress via the bay roof. These issues are often caused by old or loose lead flashings which act as a seal between the brickwork and roof line.

In the Friern Road property, the bressummer had moved causing the brickwork which sits on it, and supports the sills above, to move too. We also proposed in our report that the timber bressummer should be changed for a steel beam. Its size would be calculated by our structural engineer to ensure it was suitable.

About our work on this project

Pictured: New bay Bath stone elements in place, before decoration

Once costs were agreed we created templates of the original stone sections such as the sills, mullions, capitals, lintels etc. For insurance approval, as well as installation purposes, we also produced CAD drawings.

In our workshop we carved the stone sections, and arranged for the steel beam to be manufactured.

We also worked alongside a timber sash window company who were replacing the old bay wooden window frame. By working in conjunction with them, we were able to share drawings and ensure the new frames would fit precisely inside the new stonework.

Then we carefully dismantled the bay structure to avoid further damage to the facade brickwork of the property and any further damage to the brickwork in and around the first floor window sills.

Extensive propping was needed during the process to halt further movement. Once everything was stabilised, a new foundation was carefully excavated and concrete poured, as per the structural engineer’s calculations.

Once the concrete foundation had cured, we laid the supporting brickwork for the bay, tying it back into the existing building. Our newly carved Bath stone elements for the bay were brought to site from our workshop and installed quickly over the next week, followed by us installing the bay roof.

With this style of bay window, a timber roof is installed over joists in a traditional way but the joists are covered in marine plywood then lead lined on top to create a shallow waterproof well.

The stone parapet wall on top of this bay roof meant that a rainwater outlet was necessary, as was internal lead work that was tucked under the parapet stones and into the facade brickwork.

The result – a new, attractive, structurally sound bay window

Another view of the new bay window stone surround

Pictured: A side view of the new bay window stone surround by London Stonemasonry

The new bay window took us around four weeks to complete, which includes repointing facade brickwork and decoration to the bay and sills. 

The new parapet bay stones set this bay off beautifully and once installed the homeowner was extremely pleased to see it all coming together. The sills to the first floor windows were also replaced with Bath stone to match the new bay. 

After what had been a difficult period for the client due to poor workmanship by others, London Stonemasonry are happy to have been able to restore their confidence with our high quality work. More importantly the homeowners got their living space back, and could relax again in their beautiful sitting room.

New stone bay window Dulwich London

Pictured: A wider view of the new bay window by London Stonemasonry

See also

Project summary

London Stonemasonry expertly rebuilt an incorrectly repaired bay window, integrating new stone elements, a steel beam, and a foundation to prevent future movement. The collaboration with a timber sash window company ensured precise frame fitting. Location: Dulwich, London, SE22. 

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