Heritage conservation with lime

Students plastering lime on one of the walls of NUS Baba House

Six Architecture students literally got their hands wet and grimy in a bid to learn more about conservation of buildings at a special hands-on workshop.

Led by Dr Nikhil Joshi from NUS Architecture, the four-day workshop offered an eye-opening experience for the Year 4 students in processes such as lime slaking, preparation and application of lime plaster, as well as lime wash. The students had to mix different compositions of lime plaster and apply them as separate strips on an exposed brick wall of NUS Baba House, a heritage shophouse dedicated to Straits Chinese history and culture. The ability of these strips to deal with dampness will be tracked over the next few months to determine the optimal plaster composition for future maintenance of the property. The workshop also included lectures, discussions and viewing of buildings where lime has been employed.

Dr Joshi said that prior to the development of cement, lime plaster — a mixture of lime and sand — was usually used as the first coat of plaster on the brick walls of nearly all buildings in Singapore, while lime wash was used for painting the walls.

“Unlike most modern building materials, lime-based materials let the old buildings ‘breathe’ and move gently, an essential characteristic with historic buildings. It is necessary to raise awareness regarding the environmental benefit of lime and its use for the repair and conservation of old buildings in Singapore before it is too late,” he said. Dr Joshi added that the preparation and use of lime were no longer widely applied and hoped that through the workshop, the students would be able to expand their knowledge and skills in this area.

lime workshop 2

Students mixing lime putty and sand

One of the participants Karl Kaungpyeimaw Tan learnt that lime is carbon neutral when used as a building material, absorbing carbon dioxide from its surroundings after application. “This is important to note because in this age, many of us are looking at sustainability in building design and who would have thought lime — which had been used in the building of ancient monuments, is such a ‘green’ material,” he said. Furthermore, due to its breathable nature, lime creates a cooler indoor environment compared to cement, he shared.

The workshop is part of the curriculum on Asian Architecture and Urban Heritage Conservation and was jointly conducted by NUS Baba House and NUS Architecture.