Under the lamp

Case study

Blackheath, London

Early in 2014, we investigated the condition of a classic Victorian brick facade within the buffer zone of the Greenwich World Heritage Site.

Author

Patrick Hughes

Service

Facade/brickwork Survey

Completion

January 2024

Client

Homeowner

Blackheath Brickwork
Blackheath Brickwork

The homeowner had become concerned about the condition of the exterior brickwork and masonry and had begun to witness some localised water penetration internally at and around window reveals.

We employed visual and tactile means of investigation including; use of a tripod-mounted monocular to assess and record visual defects, thermal imaging to identify potential areas of vulnerability/failure, tap testing of render/masonry to investigate delamination and masonry sampling as laid out in BRE Guidance Note 245 to gain an initial understanding of rising and penetrating damp. Several defects were identified as a result of these works, typically relating to general weathering over time, though issues had largely been compounded by a history of insensitive repairs. This included the use of impermeable film forming paints and inappropriate cementitious mortar repairs.

Findings were compiled in a report format which included draft repair schedules, annotated drawings and a photographic record of conditions. This included cost-effective advice in relation to cleaning, efflorescence, spalling and maintenance. We recommended to the client that this document should be used to tender works for the necessary repairs to take place.

Thank you to the team at Six Heritage for your incredibly professional and expert consultancy. The findings have been very useful for planning the required works and, most importantly, it’s given me peace of mind

Homeowner

In focus – bricks and mortar

Although no formal petrography or laboratory analysis was undertaken, it was believed the principal (west) elevation facing out onto the heath was comprised of historic London stock bricks. This was based on the age and context of the structure combined with the natural yellow hue of the brickwork. This theory was further supported by the apparent presence of the typical black flecks associated with ash used within the clay mix of this brick type.

Original lime mortar used at the time of construction would have been of a similar porous nature as the brick itself, allowing for the dissipation and drying of moisture as well as low-level structural movement. The re-pointing of weathered/failed mortar over time using a much harder, cement-based mix, such as Portland cement, can cause localised spalling and damage to the softer London stock bricks as was the case here

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