On the day of the earthquake, builders were on site commencing alteration work which we had designed for the owners. Luckily no one was hurt and the builders were able to assist one of the clients to evacuate the building. They then secured the building and left site. It would be several years until the owners returned.
Once the insurer put a project manager in place we were engaged to carry out a scope of damage and repair report. The aim was to determine if this magnificent building could be retained and repaired or if it needed to be demolished and rebuilt. We determined the building could be repaired but the cost of this versus a rebuild would determine its final fate. There was a lot of good will from both the clients, insurer and project managers to try and make a repair happen.
The building has three levels with a brick ground floor and timber framed first and second floors. The timber framed floors had damage to both the interior and exterior plaster but were structurally intact. The ground floor had significant structural damage to the brick walls. Further failure of this structure would result in loss of support to the upper floors and potentially a total collapse. Therefore, the decision was quickly made to install a temporary support structure at the ground floor.
Having been involved in alterations before the earthquake we had a good set of drawings. These were based on existing drawings from an alteration by John Vial Architect and a full measure-up we had undertaken. What we were missing was a thorough understanding of the structure of the upper floors and where the load points were. Therefore, we carried out several site visits to determine the size, spacing and direction of timber joists and beams and added this information to our drawings. This enabled the structural engineer to design the temporary steel support. This was signed off by the insurer and installed by the builders who had been working on the alterations.
The work to the ground floor required the removal of all the unreinforced internal and external brick walls and their foundations. This allowed for the ground floor plan to be rethought. The owners had wanted to relocate the entrance which had previously been located around the side of the house. The ground floor had some awkward planning especially around the internal access to the double garage which had been added alongside the original single garage. There were also a number of level changes. The ground floor plan was able to be made more functional by relocating the entry off the vehicle court, reducing the number of level changes and arranging internal walls to better brace the three-level structure.
While these departures from the original plan meant some betterment cost needed to be allocated to the rebuild, the project managers recognised their benefit, and the extra cost was minimal for the substantial result gained by the client.
The planning for the upper two floors remained largely the same. On the first floor the circulation around the stair was revised as part of the relocation of the ground floor entry.
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Elevations
The next stage was to determine how the brick ground floor would be rebuilt. The engineer proposed a mix of concrete block solid filled and reinforced, and reinforced solid concrete walls combined with steel beams. The temporary steel structure remained in place until the new structure was installed and could carry the load. The engineers were overloaded with work post-earthquake and so we took on the task of completing documentation of all the structural elements. While this is work not commonly carried out by an architect it is work that I have done often in my architecture career.
Once the ground floor structure was completed the builders moved up to the first floor to install some additional steel bracing and beams. With the structure complete and the building secure the building was stripped back to its timber frame with all clay roof tiles, exterior peddle dash plaster and interior lath & plaster being removed. Some plaster board lining on the second floor which had been installed as part of a previous alteration within the roof space was in good condition and so could be retained.
The owners loved the character of their substantial family home and so the reinstatement of original materials was always going to be part of the repair strategy. This presented challenges as some of the materials were not commonly used in modern construction. We carried out research with STO of how to detail the pebble dash plaster and they recommended a plasterer experienced with traditional plaster over metal lath. We found a supplier of clay tiles in a colour and profile which matched the original Marseille tiled roof. The builder employed carpenters with experience in lead work on tiled roofs and they worked in with the roofer who did not have these skills. Together builders’, sub-trades, suppliers and Architect resolved details on site as the work progressed.
The brick to the ground floor was easier to detail as this was traditional veneer except that it was over concrete block and solid concrete rather than timber framing. More challenging was the brick chimney which extend from the ground through three floors and up above roof level. Restraining a brick chimney over the two timber floors was going to be difficult and expensive. Therefore, a lightweight solution of timber framing with brick slips was proposed by the engineer. We then had to design the chimney to replicate the existing profile and to ensure weathertightness. Working with the bricklayer we detailed 25mm brick slips which would be cut on site over a waterproof membrane on fibre cement backing on cavity battens over a rigid ply barrier and new timber framing with steel bracing frame.
The building had timber windows and doors and while many of these were retained, those on the ground floor had to be replaced as they were damaged by their adjacent brick walls during the quake. We don’t get to detail timber window and door joinery often but when we do it is always a pleasure. This project included significant timber joinery, not just external windows and doors which needed to be double glazed but also internal panelled doors, skirtings and architraves to match existing detailing. New timber details were designed for the stair balustrade at first floor level and laminated countertop to the adjacent kitchen. Timber veneer was used for portions of the kitchen joinery and this was detailed with solid timber edging.
The decision to repair rather than rebuild this home was not any easy one for the insurer or project managers to make. The owners drive to retain the building assisted by our strategy to secure the structure, scope the damage, determiner a repair methodology and design the required work has resulted in a much-loved family home being retained. Not only has the home survived the earthquake its interior has been brought up to date with an improved plan and circulation as well as modern kitchen, laundry and bathrooms. However, to the exterior the line between old and new is invisible.
