When you paint your walls, you want them to look perfect and stay that way for a long time. So, when those same walls start to “sweat” water, it can be very frustrating. But what are some reasons why walls sweat after painting, and how can they be fixed?
If walls start sweating after painting, it could be due to excessive moisture in the room or improper insulation. It could also be due to the painted area and whether it was properly sealed or not. These issues can often be resolved with dehumidifiers or by properly preparing the area before starting.
In this article, I will address some of the reasons that cause walls to sweat after they have been painted and how these problems can be fixed.
Contents
1. High ambient humidity
If your walls are very cool, condensation may occur. This can have various reasons: Maybe it just stopped raining, maybe you turned off your air conditioning and opened the windows, etc.
The main factor in this equation is humidity.
If your walls are cooler than the humid ambient air, water will form or condense on the walls. This is extremely annoying if you have just painted: You may even need to repaint or apply additional coats.
How to fix it:
If you believe the cause is moisture, the first thing you should do is boost the air conditioning to lower the humidity or install a dehumidifier if you do not have air conditioning.
If it is cold outside, consider using a space heater, and if there is insufficient ventilation, open a window or turn on a fan.
You may need to maintain this for a few days, depending on the level of humidity and damage caused.
2. Improperly installed insulation
Properly installed insulation is meant to prevent walls from sweating. However, if the insulation is not installed properly, the walls can absorb heat from outside in the summer.
In most cases, the house is cooler, so when the heat in the walls meets the cooler indoor air, condensation forms, causing the walls to sweat.
In the cooler winter months, this phenomenon is reversed: the indoor spaces are warmer and the walls are colder. Again, condensation forms when they come into contact. If you paint in extremely cold or hot months without proper ventilation, sweating is almost inevitable.
The moisture inside the indoor spaces exacerbates wall sweating as you generate moisture through showers, breathing, and any other type of running water. The more water you let run without ventilation, the more it essentially contributes to wall sweating.
How to fix it:
Apart from completely tearing out your insulation, which is unnecessary labor-intensive and expensive, there is a simple and straightforward way to solve this problem: ventilate your house.
Open windows, install fans, and generally increase air circulation. However, dehumidifiers are very helpful here as well, and even a small device will work.
To fix the issue at its source, you may need to consider replacing your insulation with a higher quality one, making sure it is properly installed by a professional.
3. You painted your bathroom
Bathrooms tend to sweat the most out of any rooms after being painted, and that is because there is so much moisture there. Even if you have a lot of air circulation in the rest of your house, the amount of water flowing into the bathroom makes it very damp.
How to fix it:
The way to prevent newly painted bathroom walls from sweating is to avoid running water into the room until the walls are completely dry.
Install fans, open all windows, and consider using a dehumidifier. While it is necessary to shower and perform other tasks in the bathroom, increasing ventilation should allow the bathroom walls to dry in no time.
Additionally, always choose a paint that indicates it is suitable for use in the bathroom. These have water and mold-resistant properties that should help seal the walls and prevent any sweating.
4. Leaching of surfactants
Surfactant leaching is a phenomenon that occurs with certain types of paints as they dry, especially with latex paints. Latex paint contains surfactants that normally migrate to the surface of the paint as it dries. When freshly applied latex paint comes into contact with humid air, the surfactants rise much faster than they should.
When this happens, the paint discolors with oily residues dripping from its surface. When the paint “soaks”, stains occur.
Depending on the humidity, the stains can be more or less severe: extremely humid air can permanently stain freshly applied paint. For this reason, it is especially important to ventilate newly painted areas.
How to fix it:
To fix surfactant leaching, simply wipe the surface with a damp cloth and ventilate the area. If you have just noticed it and take immediate action, it should fix itself.
Permanent staining from surfactant leaching is rare unless you do not notice it or intentionally ignore it because you might think it is just water.
To protect against surfactant leaching, the first step is to use a paint that is moisture-resistant. Running air conditioners can help reduce ambient humidity, or you can choose to use a dehumidifier and open some windows.
5. Poorly sealed bricks/concrete
Similar to poorly installed insulation, sweating walls can also occur if your house is made of a significant amount of concrete or bricks.
Concrete and bricks need to be sealed during construction to protect against dampness and moisture. This is particularly common in basement areas where a portion of the wall is above ground: it is common for such walls to not be properly sealed during construction and subsequently sweat.
Painting unsealed bricks or concrete is very challenging unless you seal the walls beforehand as any moisture differential can result in sweating.
Repair guide:
The only way to prevent sweating of brick and concrete walls after painting is to first apply a sealer to the exterior walls.
This will protect against moisture and its byproducts, such as moss and mold growth.
It is possible to apply a sealer to your exterior walls, but this can only be done once you have addressed the moisture issues inside. Painting over wet bricks will lock this moisture inside, leading to all sorts of damage, which can be really painful. Fortunately, most cases of sweating walls occur due to high humidity. So, if you do not have surfactant leaching, most cases of sweating walls can be resolved by boosting the air conditioning or ventilating the area.