If there is one building material that has truly withstood the test of time, it has got to be concrete. It is used in several types of structures all over the world. That’s because it gives you benefits such as durability and affordability. But you might wonder what more you can do with your concrete surface.
You can apply plaster to a concrete surface. It would be an excellent way to enhance its appearance. You just need to ensure that the concrete is completely dry before you go in with the plaster.
It’s essential to understand the type of concrete surface you are working with so that you can plaster appropriately. For instance, the plaster might not adhere properly if you are working on dense concrete due to its smoothness and low porosity. However, you can use a bonding treatment to address the issue. Alternatively, you can blast the surface to make it rough.
During application, it’s essential to apply forceful pressure and check for hollowness when the plaster dries out and when heating the building for the first time. Consider increasing the temperature gradually during heating rather than starting high.
Should You Put Plaster Over Concrete?
Plastering refers to adding layers of plaster mortar to cover the exposed surfaces of brick walls. At its most basic, plaster comprises lime or gypsum, sand or cement, and water.
Putting plaster over concrete would be a good idea, especially if you want to enhance the concrete surface’s appearance. You can do it on surfaces such as the wall, the floor, and the roof. You can even paint the plastered wall to give your surface a refreshing look.
Another benefit of applying plaster, besides its enhanced appearance, is its durability. It is far more durable than contemporary drywall. You can find many historic structures with the original plaster and still look as good as new. Plaster is also fire-resistant and rarely succumbs to water damage. Although the plaster might develop tint cracks over time, that rarely happens, mainly if you apply it correctly.
Besides, plaster is pliable. Therefore, if you would like to be creative, you can use it to create beautiful details and designs that align with the rest of the house. It’s also easy for you to apply plaster into tiny spaces, even those with irregular shapes.
Most importantly, plaster is so clean and easy to install that it leaves no dust or mess, and you can easily make it a DIY project. You just need the right tools for the job and are good to go.
What Tools Do You Need To Put Plaster Over Concrete
While it takes more than just the right tools to get the job done, they play a huge part. Having them assembled before you start the work makes sure everything runs seamlessly.
To put plaster over concrete, you will need gauging tools, leveling tools, a float, a paddle mixer, a hammer, and a sponge. But you can substitute the sponge with a water brush. You will also need a bucket to hold your plaster mixture during the plastering work.
Notably, a trowel does a decent job of gauging small amounts of the plastering mixture. Some gauging trowels are pointed at the end, while others are bull-nosed—either can work. You will also need a spackle knife, especially if the concrete surface you are working on is somewhat uneven. The knife removes the high parts, leaving you with a clean and smooth surface to work on.
When it comes to leveling, you have a few options. One of the most commonly used tools is the spirit level. It consists of a water tube that helps you check how even your work is from all angles. You can also use a straight edge—which also doubles as a measuring tool. The other option is a plumb bob, which comes in handy when you need to check the vertical levels of the wall. It usually has a thread tied to one end, while the other side has a cone shape with a pointed end.
Then you will need a float to lay and spread the plastering material over the concrete surface. You can either find one made of metal or wood. Ideally, the wooden float works well for applying the finishing coat of plaster.
Don’t forget a paddle mixer—this tool helps you mix the plastering ingredients without breaking the clamps. Finally, you will need a wet sponge to smooth out the plastered surface once you are done.
What Preparations Do You Need To Put Plaster Over Concrete
Plastering concrete surfaces goes a long way in enhancing their appearance. It also provides the perfect base for painting, whitewashing, and distempering. But you have to prepare the concrete adequately to have satisfactory results.
The most crucial part of preparing a concrete surface before plastering is cleaning it. Remove any peeling paint so that the plaster can bond with the concrete. You also need to get rid of dust and oil since they might also interfere with the bonding.
Lucky for you, concrete is pretty easy to clean. Start by sweeping or vacuuming loose dirt off the concrete surface. If you notice any stains, you can easily remove them with liquid laundry detergent and water using a stiff nylon brush. You can also use a pressure washer. If the concrete has grease or oil stains, consider using baking soda to absorb as much oil as possible. Powdered laundry detergent can also do the trick if you don’t have baking soda. Then rinse the concrete surface down with water. Remember to give it enough time to dry completely before you start plastering.
Besides cleaning the concrete surface, it is also essential to treat it with slurry—so that it can be rough enough. You can prepare slurry by mixing one part cement with one and a half parts coarse sand. Then add water to the mixture until you get a runny consistency.
How to Put Plaster Over Concrete
Once you have your tools gathered and your surface prepared, it’s time to get down to business. Make sure you follow each step correctly—remember the plaster can last for years, so you need to get it right first.
When putting a plaster over concrete, the steps involved are mixing the plaster, applying it, and curing it. When mixing the plaster, check the manufacturer’s recommendations on ratios.
Always remember to add the plaster to the water, never the plaster first. Be careful not to mix the plaster too thick since you might struggle to spread it flat.
You will need a clean bucket that is big enough to hold your mixture while leaving enough room for mixing. Then add water to the bucket, followed by the plaster, and use a paddle mixer to get a consistent mixture. Be sure to swirl the mixer in both directions so that no part goes untouched. Add the plaster gradually until you have a creamy consistency.
Now apply a base coat of the plaster with a metal trowel. The layer should be anywhere between 10 to 15 mm thick. Work in small portions ensuring that it is level. Let the base coat dry. Then go in with a second coat of plaster. This time, you can use a wooden trowel. Once again, check to see that everything is level. The second coat should be about 5 to 10 mm thick.
Once the plaster hardens, it’s time to start the curing process. You should continue curing it for about seven days. Only then can you proceed to apply a layer of paint.
If you are applying plaster on a new construction site, it might not be practical to wait until it dries completely before you apply plaster. You might consider applying the plaster to the stretched metal lathing plugged and screwed to the concrete. The only downside is that this method can be costly.
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ReadyToDIY is the owner of this article. This post was published on November 11, 2022.