Don't ignore your building's façade in 2016

A building’s exterior is often not prioritised as it should be. The façade of a building is too often left to battle with the elements, with most building owners and facilities managers opting to look after the interiors of their building rather than the exterior. We’ve worked on a vast array of projects where the build-up of dirt has caused a building’s material to become almost unrecognisable, most commonly found to be caused by a 24/7 city lifestyle and the heavy pollution this environment creates. 

Damaging dirt

The primary concern is to prevent dirt build-up, principally from airborne particulates that may contain a range of potentially problematic substrates that can react with the stone and reduce its life. Regular cleaning helps to identify areas where there is above normal build-up of dirt and salts that may be indicative of more far-reaching problems which, if rectified at an early stage, may have considerable cost benefits in the longer term.

Damp areas are particularly likely to attract dirt, especially in a wet climate and can be identified as a result of a clean if not already apparent. Thick layers of grime can retain water against or within masonry resulting in increased salt cycling in the masonry and accelerated deterioration.

Most stone façades are normally quite easy to treat, and with the nature of our scaffold-free system it’s possible to arrive on site and get up and running within two hours. The main difficulties come when dirt or soiling includes disfiguring pollutant or sulphate crusts, which usually build up in sheltered or protected areas not regularly washed by the natural action of rain. They are particularly common under cornices, window sills, or other projecting decorative features – common with buildings in London – and if left for some time untreated, the removal process can sometimes involve a loss of a small amount of stone resulting in further costs and issues to building owners alike.

Façade Gommage technique

Thomann-Hanry’s ‘Façade Gommage’ technique cleans the exterior of stone buildings avoiding scaffold which can make the works significantly easier. Business can run as usual to minimise loss of trade and maintain that ‘as normal’ functionality, throughout. Lack of scaffold also ensures improved security during the operational period – a particular benefit to sectors where security is paramount such as banks or hotels. 

The system uses specialist cleaning operatives who work from a vacuum cabin attached to a hydraulic boom. Ultra-fine, non-abrasive powder is then projected under low pressure onto the façade and removes accumulated pollution deposits without affecting the masonry beneath. No water or chemicals are used in the cleaning process and all dirt and spent powder is captured within the cabin and removed for recycling.

Bank revamp

The Bank of England recently received an exterior clean using Thomann-Hanry’s ‘façade gommage’ system. Taking just 25 days to complete, the works took place without the use of unsightly scaffold and at weekends only to minimise disruption. 

Thomann-Hanry also undertook required stone restoration and leadwork repairs as part of the revamp. The works took place across Threadneedle Street, Prince’s Street, Lothbury and Bartholomew Lane and covered an area of 10,000 square metres. The exterior wall, known as ‘the Soane Wall’ after the Bank of England’s renown surveyor Sir John Soane now looks in pristine condition since the project was complete.