Summary: SARL Dobson Structures conducted a structural survey of a commercial property on a historic street in Paris, identifying key issues with basement stairs, a stone arch, and non-standard alterations to a steel beam. Proposed works include replacing unsafe stairs, repointing the arch with lime-based mortar, and upgrading structural supports. We look forward to collaborating on future renovation designs to ensure the building's safety and longevity.
SARL Dobson Structures recently carried out a structural survey for a commercial unit in Brittany, commissioned by CS2 Limited. The property, a natural stone building with a historic basement arch, had undergone various non-standard alterations over time. Our survey identified several structural concerns and proposed initial recommendations to ensure the building's long-term stability and safety.
Key Findings from the Survey
1. Basement Stairs and Stud Wall Support:The existing basement stairs displayed significant structural issues, including improper repairs with steel angles and sloped treads due to deformation. Additionally, a nearby stud wall was improperly supported, relying on a single timber stud connected to the stair tread. This arrangement compromises the structural integrity and requires immediate attention.
2. Historic Stone Arch:The basement arch, constructed from natural stone, appeared structurally sound, with no visible cracking. However, erosion of the stone was noted, likely due to the use of cement-based mortar, which traps moisture and accelerates deterioration. Repointing the arch with breathable lime-based mortar is essential to preserve its integrity.
3. Cut Steel Beam and Masonry Column:A steel beam had been cut short, with a masonry column added for support. The column's inadequate dimensions and eccentric load application created further instability. Additionally, a welded steel angle supporting the stairs requires investigation, as its placement may induce torsional forces into the beam.
4. Ventilation and Minor Cracking:While the basement's ventilation system was generally clear, one vent was obstructed with plywood, limiting inspection. Upstairs, plaster cracks were deemed cosmetic and unrelated to structural concerns.
Proposed Works
To address these issues, we recommend:
Replacing the Stud Wall and Stairs:Â Remove and replace the existing stairs and provide proper support for the stud wall, ensuring loads are transferred to the basement floor.
Repointing the Arch:Â Use lime-based mortar to preserve the stone arch and prevent further erosion.
Installing a Steel Column:Â Replace the inadequate masonry column with a steel section (e.g., 160 SHS 5.0), subject to detailed structural calculations.
Investigating the Steel Angle:Â Further assessment of the angle welded to the beam is necessary to ensure stability and proper load transfer.
Looking Ahead
We hope to assist with the structural design and calculations required for these renovations in collaboration with a local architect. This would help transform the property into a safe and functional space while respecting its historic character.
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