This article is about how to plaster a brick wall. After you have cement rendered the brick walls of your room, you have to prepare them for the paint coats by applying the plaster. Plastering a brick wall is not a complex task, being similar to plastering a drywall, but you have to follow a couple of guidelines, as to get the job done in a professional manner. Consequently, you must apply two coats of plaster, the first one a little more coarse, while the second one should be very fine. After the two coats have dried out, you have to sand thoroughly the surface, as to make it even and neat.
Make sure the surface is ready to apply plaster. If we speak of a new construction, then you should make sure you have cement rendered the walls and let them dry for a couple of days. If you want to plaster an old room, then you have to remove the coats of paint and sand the surface thoroughly. In addition, cover the walls with PVA bonding, according to the manufacturer’s instructions, as to make sure the plaster will adhere to the walls.
In order to mix the plaster, you need several tools: a clean construction bucket and a drill mixer / margin trowel. Pour water in the bucket (1/3 of the volume) and then add gradually the plaster. After a couple of minutes you have to mix thoroughly the compounds, until you get a material with the consistency of cream. If the plaster doesn’t fall off the trowel, it means that it has the right consistency.
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In order to plaster a brick wall, you need the following:
- Safety gloves, glasses, respiratory mask
- Margin trowel to load the plaster trowel
- Plaster trowel, medium-grit and fine-grit sandpaper
- Construction buckets to mix the plaster
- Apply the finish plaster after the first coat has dried out
- Check for imperfections after sanding the wall and fill them
- First coat: One day, 100 sq feet / 10 m2
- Second coat: One day, 100 sq feet / 10 m2
How to plaster a brick wall
Before being able to paint your room, you have to plaster the walls as to even out the surface. Consequently, you have to apply two coats of plaster: the first one should be medium-grit, while the second one should be very fine.
First of all you have to prepare the plaster, either by hand (by using a trowel) or mechanically (by using a drill machinery with a mixing paddle). Pour a gallon of water (3 l) in a construction bucket, pour the plaster and let them for 5 minutes. Mix the compounds until it gets the consistency of cream.
After you have mixed the plaster, you have to spread it on the brick wall, by using a plaster trowel. In addition, you have to load the plaster on the trowel, by using a 4” palette knife. Another option is to use a hawk, but any of these will work fine.
In order to plaster a brick wall, you have to use repetitive semicircular moves , until you get an even coat on the whole surface. Make sure you hold the plaster trowel angled while you are skimming the wall, creating a layer of about 1/10” – 2 mm thick.
Continue the process of plastering the brick wall in the same manner, making sure you mix the material every 10 minutes and add a little water if necessarily. Generally speaking, the plaster dries out quickly, that is why you have to make sure it has the right consistency before skimming the brick wall.
As a general rule, if the plaster has the right consistency, then it will not fall off the trowel. Spread the first coat evenly, but do not worry if you notice a slight texture, as you will fix it later on.
In this image you can see in detail the way in which you have to plaster a brick wall. Therefore, keep in mind these essential aspects: the plaster should have the right consistency and it should be mixed properly, you should hold the plaster trowel at angle and try to skim an even layer.
Another aspect you should take into account is the joints of the walls with the ceiling. As you can see in the image, you have to plaster the walls up to the ceiling. If those areas are inaccessible, then you have to use either a folding ladder or a workbench. Make sure the base surface is level, otherwise you risk injuring yourself.
Work with patience and every 10 minutes assess your work by looking at it from distance. The coat shouldn’t be perfectly even, but in the same time make sure it is at least decent.
Next, allow the plaster to dry out for 20 minutes before repairing the irregularities. Consequently, use the plaster trowel and go over the surface again, making it even and smooth. Remember that you don’t have to push the trowel too firmly, but in such a way to smoothen the surface.
If you notice drags or holes in the coat of plaster, you should add a little more material until you remove them definitively. In addition, you could also sprinkle water on the wall, by using a large brush, and then trowel the plaster with the float.
Plastering a brick wall: the second coat
After you have spread the first layer of plaster, you should let it dry for at least one day. Then, you have to apply the final coat of plaster using the same techniques described above.
The final coat should be much finer, so make sure you buy the right one from your local diy store. In the image you can see that you have to plaster the wall around the light switches and electric outlets, so make sure you turn off the electricity before stating the work.
The final coat of plaster must be applied on the whole surface of your room, so make sure you cover it evenly. Use the trowel to spread the plaster on the wall and try to cover all the irregularities.
Work with patience and make sure you mix thoroughly the plaster before skimming the wall. Plaster the whole surface of your room, from bottom up to the ceiling, around the sockets and light switches.
In this image you can see that you also have to plaster the walls around the windows and install corner beads, if necessary. Installing a metal corner bead on a brick wall is not complex, but it can make a difference if secured properly.
The main advantage of the corner bead is that it reinforces the edges against hits, and that it creates a straight edge from top to bottom. In addition, when plastering the brick walls, the coat will hide the corner bead, to the point where a person wouldn’t notice it at all.
In order to have access to the top areas of the wall, you have to use either a folding ladder or a workbench. Make sure the base surface is level, otherwise you risk injuring yourself during the project.
Spread the material evenly, moving the plaster trowel upward and downward, as well with circular moves. Remember that the final coat of plaster doesn’t have to be too thick, so make sure you spread the material as much as possible.
Sanding the plaster
After plastering the brick wall with a second coat, you have to leave it for at least a day to dry out. The next step of the plastering process, is to sand the surface with different granulations of sandpaper. Therefore, you have to use a medium-grit sandpaper at first, to remove the bigger irregularities, and then end the project by using fine-grit sandpaper.
Before sanding the walls, you have to mask the door and the other objects in the room (wires, radiator valves and so on) with paper tape and plastic foil. In addition, we strongly recommend you to wear a respiratory mask, as while sanding the plastered walls you will create a lot of dust. Inhaling the dust would irritate your respiratory system, so wear the mask and a pair of glasses, just to be safe.
Sanding the plaster walls is a serious job, as it is an essential step before painting the room. A poor job will be noticeable as the walls won’t be even and smooth, therefore you have to focus and work with great care.
Therefore, the best way to sand the walls is to use a sand block. Of course that you could use a sanding pad, but the cheapest way is to use a sanding block. Moreover, you have to use first a medium-grit sandpaper (120 will do fine) and smoothen the whole surface of your room, making sure you don’t miss any spot. Later on, you have to sand the plaster by using fine-grit sandpaper (150 is perfect).
Sand the surface with the medium grit sandpaper, making sure you don’t miss any spots. It is essential to cover the whole area with the sanding block, otherwise the walls won’t be uniform. Use circular moves and insist in the areas which aren’t consistent with the rest of the surface.
Next, you have to sand the walls again, this time using a very fine-grit sandpaper. This process will smoothen the appearance of the plaster coat and make it very uniform. Sand the plaster walls thoroughly, until you remove all irregularities, making sure they are perfectly level and even.
In the image you can see different areas which have a darker color as the rest of the wall. The explanation is very simple: the light color represents the second coat of plaster, while the darker areas represent the first coat of plaster. When sanding the surface, you will expose, in some areas, the first layer of plaster, which means that you have evened out the walls.
In this image you can see the dust resulting from the sanding process, and you have to trust me, there will be a lot of dust all over the floor. Therefore you should be ready to clean it, by using a vacuum.
Under any circumstances don’t use a broom, as you will make it worse. Nevertheless, if you want to brush it, you could sprinkle water over it. In this way the dust won’t raise in the air when using a broom.
After the hard work you can rest for awhile, as to enjoy the result of your efforts. The surface of the walls should be uniform and ready for paint. Make sure you check again the surface of the walls before applying the paint, as to spot for irregularities and drags.
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