Although the brickwork is fairly easy to do yourself if you have the time, most hobbyists agree that plastering or rendering of the walls is one task that they prefer to get done by a professional. There are two methods that you can use for plastering
The first method is to do the rendering with two coats. The reason for plastering with two thin coats is the fact that a mortar mixture only consists of sand and cement and it is prone to hairline cracks if applied too thick. The first coat is applied directly to the brickwork. The cement consists of the normal mortar mix of three parts sand to one part cement. When it is completed, the surface is roughed up with a trowel so that the final coat will adhere to it easily. The second coat is made up to the same mix, but this time you add another ingredient. It is a waterproofing agent, and the instructions on the container will tell you the amount required. A product that I have found to be very effective is Sikalite that can be obtained from most hardware stores. Follow the instructions to the letter and you will have a rendered finish that is smooth and waterproof as long as your pond don’t crack. Mix the sand and cement thoroughly with the Sikalite before adding the water. Please remember that this coat should be no more than five to eight millimetres thick. It is further recommended that this method be used, even if you are going to fibreglass the inside of the pond.
The second method is to add another ingredient called Fibromix. This material consists of glass fibres, and is broken up and added to the mix. The fibre helps to bind the cement together and gives a stronger surface, which minimises surface cracking. First mix the sand, cement and Sikalite thoroughly while dry before adding the water. After this, the fibres are slowly added with additional water as necessary. Thorough mixing, to uniformly distribute the fibres throughout the mix, is essential. Only sufficient water should be added to give the desired degree of workability - excessive water is deleterious and should be avoided. The final surface of the render should not be too smooth and most professionals use a sponge in circular movements. Do not use a steel trowel. This allows any additional waterproofing coat to adhere more easily to the surface. When using this method, the thickness of the coat is not as important, because the fibres will prevent small cracks from forming. Fibromix can be used even when the pond is going to be fibreglassed.
Last Updated on Wednesday, 11 March 2009 15:19