Details

Client:St Paul’s Restoration Trust

Location:Spring Hill, Queensland

Disciplines:Heritage

Industries:Public Realm

Awards:

2015 Premiers Sustainability Finalist Award for Sustainable Heritage.

2015 National Trust Queensland Heritage Silver Award.

About the Project

The church was designed by former colonial architect, FDG Stanley and is now over 125 years old, having been completed in 1889.  It is one of the few Brisbane church buildings to be fully realised in stone with masonry elements used in all external walls along with the tower and spire.  Stone has been used throughout with comparatively little ornamentation being employed, typical of the Presbyterian Tradition.  The church precinct was listed by the Australian Heritage Commission in 1978, being placed on the “Register of the National Estate”.  St Paul’s was later added to the Queensland Heritage Register in October 1992 and a Conservation Management Plan for the church precinct was prepared in 1994 by PDT Architects which is held by the Queensland Heritage Council and used as the basis for assessment of any works proposed to the site.

PDT Architects have enjoyed a long association with the Church and the adjacent Hall building for over 30 years. During this time some of the previous projects undertaken have included;

Internal refurbishment of hall
Roof sheeting replaced to both the church and hall buildings plus coping stones and carvings restored.
Helidon sandstone to the church front entrance restored.
Copper cladding to the church spire.
Restoration of the feature stone pinnacles to church building.
Repointing of stonework throughout both the church and hall buildings.
Refurbishment of existing feature timber doors to both the church and hall buildings.
Leadlight window glazed protection panels provided.
Ongoing annual condition audit.

An audit of the church was performed in 2012 and the tower walls were identified as the most urgent element requiring remedial works due to its advanced state of deterioration.  The audit report identified that three major stone types used in the construction of the church building are evident on the tower walls.  These include Porphyry, or Brisbane Tuff, as the main structural element in combination with Murphy’s Creek Sandstone and Woogaroo Sandstone, both used for the features, water tables and carved elements.  The Porphyry is the dominant material used in the wall construction and generally exists in good condition with some isolated areas requiring remedial work, and larger areas requiring repointing to the joints. The Murphy’s Creek sandstone has a fine grain and has generally been used for the reveals and jambs to the window openings and for some of the banding and is generally in good condition with some isolated cracking and damage.  The second type of sandstone from the Woogaroo Quarry near Goodna, has a coarse grain, and has been used for the majority of the banding and for the carved features and unfortunately exists in varying degrees of weathering and generally required the most significant attention.  This sandstone has a tendency to allow water penetration into its substrate which results in large sections de-laminating.  Some sections have become so deteriorated that the stonemason was able to remove pieces easily by hand and, if left unattended, these would eventually come free from the facade. As well as the obvious safety issue, each subsequent piece that comes free also allows water penetration into the stone below, and the process of weathering accelerates.

The conservation principles and methods adopted for the conservation of the masonry to the church tower were aligned with the policies of the Conservation Management Plan.  The use of maintenance and preservation was favoured and the introduction of new fabric was utilised only where the masonry had become completely deteriorated, had been previously removed, or deemed unsafe to retain.  The  objective  of  the  work was  to  conserve in  place  as  much  as  possible  of  the original fabric. The stonemason’s approach was that all sound stone was retained intact where appropriate and replacement with new stone using an indent method was only utilised where the material was identified in an advanced state of decay during the audit process. The replacement of any masonry included a detailed site measure to establish their exact proportions, as all new stones not only match the profiles and features of the original stone, but also match the exact coursing, both horizontally and vertically. The depth of the replacement stone was determined to ensure it would be self-supporting on the vertical axis.   Each stone was carved off site to detailed site measurements and final working performed on site to ensure joint tolerances of 1mm maximum thickness was achieved when aligned to the adjacent new and existing stone.  This also required the removal of flattened planes and machine or other tool marks by wet carborundum rubbing.

The existing sandstone identified to be retained also required a process of dressing back and tooling to remove any fretting to the stone face.  The dressing back is not performed for cosmetic reasons, but rather to reinstate the stone finish to improve its resistance to future weathering. The work was carried out by hand using a mason's chisel or by hand held carborundum stone.  After dressing back the stone was washed down to remove stone fragments and dust. Repointing was also performed to large sections of the existing porphyry stone.  The existing joints were removed both horizontally and vertically to a depth of 15mm nominal, and new repointing provided with colour and texture to match existing adjacent retained repointing.

 

Project Team

Tim O’Donnell

Associate

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