Guest post – Alan Kelsall on the Art of Heritage Restoration

As the Heritage Festival is about to kick off I thought it a good opportunity to have City of Fremantle Heritage Coordinator Alan Kelsall talk about some of the recent heritage restoration projects the City of Fremantle has been undertaking. Here he looks at the Union Stores (which includes New Edition on the corner) which is one of the many properties owned in Fremantle by the Council and is undergoing a sensitive makeover.

Union Stores 1

Union Stores – Urgent conservation works were recently undertaken to the parapet and gables of the Union Stores building at the corner of High and Henry Streets in the West End. The external walls of the Union Stores building were constructed using what are now described as traditional construction.  As with nearly all 19th and early 20th century buildings in Fremantle, the conservation works in part consisted of doing what was necessary to allow the fabric of the building to perform as originally intended.  In other words, removing the well-intentioned but damaging ‘repairs’ of the past 30 years that had been carried out using modern materials often hoping to reduce the need for regular maintenance.

The mistakes of the recent past stem from not recognising the benefits of allowing the walls of traditionally constructed buildings to breathe, which in turn led to the importance of the contribution made by traditional materials to this process being undervalued.  Traditional materials, such as lime-based mortars and limewash, are permeable whereas modern building materials, such as acrylic paints, sealers and cement render and mortars are not.  Traditional materials allow the walls to breathe and bring about the natural evaporation of any moisture and, importantly, cause the salts carried by the moisture to migrate slowly towards the surface and accumulate there.

The removal of the low permeability acrylic paint and cement render from the parapet has allowed this process to begin at the Union Stores building.  As a result, a large amount of salt has come to the surface in a very short period.  This is a good sign because previously the fine pores of the brickwork could not accommodate the increasing accumulation of salts and were eventually broken apart by the expansive forces of salt crystallisation.  This led to the slow but severe deterioration of the bricks as can be seen in the photograph of the inside face of the parapet. .This deterioration is caused salt attack and it is the principal cause of decay in masonry buildings in Fremantle.

Union Stores 2

Decayed brickwork to back of parapet, Henry Street facade

 

A further benefit of lime mortars and renders is that they are softer than the original masonry and tend to decay over time rather than the masonry.  Hence the sacrificial decay of lime mortars and renders is a useful way of managing salt damp because it protects significant fabric and in the long term it usually proves to be the most cost effective way of caring for a building because it is cheaper and easier to re-point at regular intervals than it is to replace the brickwork.

Fremantle’s maritime environment means it will not be possible to completely cure the salt damp.  Instead Council’s strategy is to adopt a maintenance approach to manage the problem by ensuring that the salt concentration occurs relatively close to the surface and, as with any maintenance programme, it will require periodic renewal of decayed fabric.  Given the severity of the problems caused by the long-term build up of salts within the walls this is going to take time and further repairs before the walls are effectively desalinated to a point where the cycle of wetting and drying causes little decay of the fabric.

 

Union Stores 3

Salt crystals forming on the cornice following the removal of acrylic paint and the deterioration of the limewash

 

The works to the Union Stores building is part of the orderly process for the conservation and care of the City’s portfolio of heritage assets.  The intention is to address building conservation in a manner that considers levels of urgency, economies of scale, correct sequence and good conservation practice.  Many of these items of work, such as those at Union Stores building, will not be conspicuous but are vital to the conservation and long-term sustainability of these important heritage buildings for present and future generations.

Future works are planned to continue the conservation of the building facade once the moisture has evaporated from the walls and the damaging salts have migrated to the surface.

Union Stores 4

Reconstructed decorative stucco-work on the High Street pediment. Behind can be seen the collapsible handrails of the new roof access system.

About Mayor of Fremantle Brad Pettitt's blog
City of Fremantle Mayor

One Response to Guest post – Alan Kelsall on the Art of Heritage Restoration

  1. Robert Bodkin says:

    You should send this to all the owners of Heritage buildings and perhaps have compulsory inspection as I doubt that most would know what they have or in fact care to follow this path

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