Vernacular building skills and plaster mixes

Owning a house that is nearly 200 years old means that one needs to do constant maintenance. I believe the true test of whether one is compatible with a historical building, is the measure to which one is prepared to learn traditional skills. Before undertaking the task of restoring your own historical building, one needs to research the building skills and materials of the period in which the building was built. Building practice has evolved immensely over the last century, making contemporary building practice largely incompatible with old buildings. It is often best to consult a professional.

The kitchen gable missing a piece of strap moulding

Most old buildings in the Cape were built with natural materials such as stone, and relatively soft sun-baked bricks, lime plaster and clay. Concrete and strong mixes of cement mortar are usually incompatible with 19th and early 20th century rural Cape building material. If one uses the wrong mortar mix on an old building, it often leads to cracking, uneven settlement and general permeability and adhesion problems, amongst others.

Tools of the trade

Visiting historical buildings many years ago with renowned restoration architects like Dirk Visser and Gawie Fagan was, and remains a privilege in terms of the insight the experience provided. Their passion for this built heritage prepared us for a life of loving old buildings and caring for them.

Keith repairing the inside of the chimney cowl

Restorers generally use a softer mix of lime plaster. The precise ratio may vary from one restoration specialist to another. We have found that a mix of 8 parts sand, 2 lime and 1 cement has worked well on the restoration of Towerwater which commenced 27 years ago.

Preparation

Plastering

When a piece of strap moulding came loose on the kitchen gable-end at Towerwater, it was time to do some maintenance on the ‘old lady’. Luckily Keith, quite unrelated to his profession, is also a skilled plasterer. The greatest challenge was to create a secure working space for him on the steep thatched roof. The top of the gable is very high and one needs to be sure of foot to rule out the risk of serious injury.

Floating the plaster

I am not sure that our measures undertaken to creating a secure working environment for the repair of the moulding would have passed modern building safety regulations. But, we employed a tried and tested vernacular solution for a vernacular repair problem.

Repair work complete

Plastering is a skill that Keith learnt as a young boy. I am always amazed at how effortless he can make it look. In no time the strap moulding was repaired. When it was properly dry, it could be lime washed.

Repair work limewashed

With Keith’s plaster skills and a plaster mix that has stood the test of time at Towerwater, the main house was soon sporting a fresh looking strap moulding. One realises at moments like this how important it is to have the right skills and knowledge to not only restore a historical vernacular building but to maintain it as well. After all, such skills and/or knowledge, would have been commonplace among home owners in centuries past.