Exteriors of a house are constantly exposed to severely acting elements of weather. In
You have many choices for the exterior surfaces and the elevation. You can have exposed brickwork or plastered surfaces or a combination of both or cladding of walls with various types of stones or textured finish. While choosing exterior finish, our main purpose is to make the elevation look beautiful and appealing, to have a durable finish that survives for a few years, at least, to choose a finish that resists dust and weathering effects and the one that breathes -- allows moisture of walls to escape without hurting their beauty.
All these aspects can be well fulfilled through right choice of finish and proper workmanship. Here are a few guidelines for durable painting of exterior surfaces, but first choose what you want.
Exposed Brick
Many homeowners prefer exposed brickwork on the elevation. Since ages, man has been seeing exposed brickwork in buildings, monuments and forts and an inbuilt desire to have part elevation with it remains. However, the decision to have exposed brick in the elevation should be made early and one should keep sorting out good bricks while doing the brickwork of foundations and internal walls of the house and use these bricks in exposed brickwork for a uniform look. Otherwise, use mechanised bricks. When the exposed brickwork of external walls is in progress, do raking of joints to a depth of 10 mm at least while it is still green. Before applying paint, make sure to do pointing.
Pointing: Prefer deep pointing to flush. Flush pointing doesn’t look good on brickwork and mars its very character. Always begin deep pointing work from top downwards. See that all extra mortar is cleaned off and not smeared over the bricks. Do pointing work with 1:2 cement sand mortar. Take care that the vertical joints are truly at right angles to horizontal lines and any minor errors in brickwork are hidden by the pointing work. A very important point to see is that the vertical lines should not end away from horizontal lines nor should these extend into them creating ridges there. Cure the pointing work well for at least seven days.
Cement Paint
If you choose cement paints, commonly known by the trade name Snowcem, on external surfaces, choose a reputed brand like Super Snowcem by Killick Nixon or the one by Asian Paints. Always choose from a fresh lot and see that the bags are IS 5410 marked. Open a bag, feel the Snowcem in your hand and see that it is free of lumps. In general, cement paint bags or sealed drums showing date of manufacture as within one year of purchase are considered fit but try to get a lot as fresh as possible. Reason for this is that cement paints are just a mixture of cement and pigments and cement attracts moisture from air and loses strength with time. So, don’t go by the expiry date on the bags or drums but get a lot as fresh as possible.
Preparation: While preparing cement paint for exterior walls, take care that dry powder is added to water and not water to powder. First take 50 per cent quantity of water to make a paste and then add balance 50 per cent to make a workable mix. Always mix thoroughly. At one time, mix only a quantity that will get used up within an hour of mixing with water. Otherwise, the paint mixture will start setting, will lose strength and brush marks will appear on surfaces.
The coats method: Clean exterior walls of dirt, dust, loose material and efflorescence with wire brush and then by washing, before applying the first coat of Snowcem. Thoroughly wet the surface before applying paint. Apply second coat after 24 hours of first. However, you need not wet the surface before applying second coat. After second coat, keep the surface fully wet for next two days by spraying water on the paint and not by throwing water with a pipe or container. I recommend a fog spray. It is a tried method and yields best results.
Texture Paint
In case you don’t want to paint the exterior plastered walls with Snowcem, consider Birla White Textura. Textura is also a cement-based paint but gives a textured wall finish — as the name suggests — instead of a plain surface. It comes in a variety of textures and designs. Unlike acrylic paint, no primer coat is required and is an economical textured finish. Above all, Textura needs no curing, has extra adhesive strength and resists water and weather. It is mixed with water and applied with trowel or roller or spray. Roller or spray finish textura is termed as RF while trowel finish textura is called TF.
The method: Prefer to use RF textura on interior surfaces and TF textura on the exterior. Textura contains Birla white cement, some minerals, polymers, quartz sand and additives. You can apply it even on damp walls. Textura TF and RF are sold in 25 kg bags. A bag costs around Rs 700. Generally, a bag cover gives 100 sq ft. area. Though the textura shade card may show many colours, it is applied only in white colour and then paints like Apex are applied over it. Its overall cost, including labour, should be about Rs 16 to 18 a sq ft. While applying, take care that at one time, only that much quantity is prepared that can be used up in 1.5-2 hours. To prepare its solution, add about 45-50 per cent water to it. If you want to use the spray method, some more water may be added to make it sprayable with a gun.
Acrylic Emulsion
Cement paints used for painting external surfaces of walls are not fully resistant to algae and fungus. Other paints available are semi acrylic and 100 per cent acrylic exterior emulsion paints. These paints give extremely good performance and also provide protection against fungus and algae. However, these are many times costlier than Cement paints. Therefore, you must make your cost calculations and buy paints your budget allows. All inclusive cost of semi-acrylic paints is around Rs 6- 8 per sq ft. This includes labour component. Good semi-acrylic paint costs around Rs 100-125 a litre. One litre should cover about 50 sq ft. area in two coats. No water curing of this paint is required.
Cost factor: For really good results, choose a 100 per cent acrylic exterior emulsion paint. It costs around Rs 180-220 a litre and covers around 50 sq ft area in two coats. All-inclusive cost of its application shall be about Rs 10-12 per sq ft. Today, labour component is very high and tends to equal material cost if you engage skilled painters. Do no water curing for this type of paint as well.
More tips on paintwork shall follow. Till then, happy painting!
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