Tips on plastering a house

Plastering is the process of covering rough walls and uneven surfaces in the construction of houses and other structures with a plastic material called plaster. 

This is a mixture of lime or cement concrete and sand along with the required quantity of water. 

David Kireli, a civil engineer at the Ministry of Education and an expert in construction answers some questions and gives tips on what to look out for when plastering your building.

 Do I need a professional to plaster my building or can any artisan do it?

When doing house finishing, some people choose to hire professionals, while others do the work themselves. One should check out the area to be worked on and the soil conditions, before mixing cement and sand. It is still better to have professionals.

 Do ratios of the required building materials matter?

If the internal and external conditions are good, a mix of 1:4 cement-sand would be ideal. But if the conditions, especially the external, are not good, then the mixes can be adjusted to 1:3 cement-sand. 

When dealing with wet conditions, waterproof cement or agents should be used. The mixes quoted above depend on the type of cement used.

 What is the right time to fit the doors and windows, is it before or after plastering?

Windows and doors should be fitted before plastering to get good finishing.

Ensure that plaster gauges are set out by the builder in case of square and rectangular rooms and that building equipment such as squares and straight lines are used. 

These help to correct defects left behind during brickwork, hence ensuring quality surfaces. The quality of plastering will lead to quality tiling work.

 How should a builder prepare the surface?

Most builders do not prepare the surface before plastering it, yet this is important. Your builder should remove dirt, grout and old plaster from the wall before they embark on plastering. This gives you the smooth surface you need to plaster.

 How are gaps and cracks prevented?

This should be done first by filling gaps and cracks in the wall before applying the first coat. This creates a smooth surface for you to work with.

 How do I get the right mixture?

For one to get the plaster mix right, they should slowly apply the first coat, while filling all the cracks. 

The best way to achieve this is to level the surface with a trowel, then add the plaster to the water and not the other way around. A top tip is to first add enough plaster so that it heaps on top of the water, then mix until it becomes lump-free.

 After mixing do I need to rush?

The surface gradually improves at the various drying stages of plastering. 

After letting the first layer dry, continue to spread an even amount of plaster over the surface with your trowel, while maintaining a flat surface. One should not over-polish the final layer because this may damage it. 

One can put a pattern on the plaster to make a good design. If not, they should just smoothen it. 

Although exterior painting and plastering may seem simple, it can easily turn into a disaster, costing more money to put right, if one is not careful.

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