Wall rendering in simple terms means plastering of walls. In every house walls need to be strong and hence it is important to plaster the walls. Rendering provides protection from damage by external elements such as air, water and sunshine.
It protects walls from wind damage and rain as it allows the water to evaporate before it can soak the walls. The plaster is usually made of lime or Portland cement and is used as a protection layer to brick walls. Rendering is important for both external and internal walls. Whether you go for brick or concrete rendering, you must try to finish the coat of paints, so that the wall remains immune to harsh weather conditions for a long time.
a) Readying the wall for rendering While wall rendering is best left to experts, it helps to understand the process nevertheless.
This is the first step in wall rendering. In the brick wall apply a coat of Portland cement and let it dry. If the older plaster is deteriorating, remove it or scrape it as much as possible. You should not spread water more than a certain amount, so that the rendering does not become soft and porous.
b) Prepare the render
Renders are made up of 3 essential elements which are sand, lime and water. One can also use Portland cement instead of lime as Portland cement makes a strong plaster and is durable. Mix one part of lime to three parts of cement. It is important to remember that the sand used in renders must be coarse. Add enough water to form a stiff plaster. Mix the renders on a concrete surface and this mix must be used within 30 minutes of its preparation.
The first layer of plaster is also known as scratch coat. There must be several coats of plaster on the walls to make it strong and stiff. The first layer of coat must be prepared with coarse sand only. A trowel is used to apply the plaster on the walls.
c) Apply multiple layers of plaster
After applying the first coat of render, scratch the surface before the coat is completely set. Then apply more coats of plaster and let it dry slowly. After the desired thickness is achieved smooth the surface with a trowel or steel float. After applying each coat, let it dry for at least 3 days. Once it dries completely then the process of rendering the wall is complete.
There are different ways of finishing wall rendering, which are as follows:-
a) Trowel finish
The final coat should be skimmed using a wooden float which produces a smooth surface. Trowels are usually used to smooth the walls surface.
b) Patterned finish
Patterned finish can be achieved by rubbing a damp hessian onto the surface of the wall which produces different patterns. These patterns give a different and attractive look to the walls.
c) Sponge finish
Using a damp sponge rub on the surface of the walls to get the desired sponge finish. The important thing is squeeze the sponge properly so that water does not run down the walls while sponging as this will wash out the cement of the render.
Usually for the final coat fine sand is used in the mix; however the textured finish can be achieved by adding coarser sand to the mix while applying the final coat.
d) Textured finish
Wall rendering is an important step in home improvement and sufficient care should be taken while plastering the walls. It is recommended by experts that rendering should be done early morning or late afternoon to have stronger renders on the walls.