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Exterior Paint Bubbling After Rain? Here’s What To Do

exterior paint bubbling after rain

You have worked hard to either pay for your home to be painted or you have done a fairly extensive DIY job. You are pleased with the outcome – your home looks great.

Then it rains, and the next day, you notice that the paint work is bubbling in some spots.

This is a huge disappointment, and will take a lot of hard work to fix. So, what has caused it, and what can you do about it? Is there anything you (or your contractor) could have done to prevent it in the first place? It’s time to find out…

How Paint Dries: The Basics

You may have wondered why paint will dry when it has been spread on a wall, but does not dry out when left in its tin. Exterior paints are generally oil based with a solvent, and react with the air through a chemical reaction.

So when they are in their tin, they are not exposed to oxygen, and therefore do not dry out. This chemical reaction allows the small molecules of the oils to form larger ones that have a more solid form, creating a polymer as it is spread on the wall.

As paint dries, the solvent starts to evaporate, leaving behind the pigment (colour), and the oil or binder. These last two will form as hard film as it reacts with the air.

It is important that this drying process takes place slowly and evenly, to achieve the best and most uniform finish.

Interior paint is often water based and therefore it dries more quickly. The water is the solvent equivalent and the part of the paint that evaporates.

exterior paint bubbling after rain

Bubbles that occur on paint after it rains almost always happen very soon after the paint has been applied, and before it has had a chance to dry properly – often within the first 24 hours, although it could happen up to a week or more after the application

What Causes Bubbles In Paint?

Bubbles in paint are caused by a difference in drying times between the layer of paint that is close to the wall, and that which is facing the sun. This can happen when paint is applied to the wall that has not been dried out completely.

As the paint dries at different rates, it begins to pull and contract on one side, and stretch on the other, causing a bubble to form. The other way this can happen is if it rains on paint before it has dried completely.

Bubbles that occur on paint after it rains almost always happen very soon after the paint has been applied, and before it has had a chance to dry properly – often within the first 24 hours, although it could happen up to a week or more after the application.

It usually requires quite heavy rain, as the moisture needs to force itself into the surface of the paint while it is still permeable.

This water becomes trapped between the layer of paint and the wall surface, causing a bubble as it starts to dry. This then leads to the scenario described above, where the wall has become wet and cooler than the outside surface.

In some cases the bubble may disappear on its own especially if they are tiny bubbles, however in most cases it requires a repaint.

exterior paint bubbling after rain

While the water trapped under the bubbles may seem insignificant, it is when these bubbles eventually crack and burst that the problems can really begin. The area exposed to the wet weather is suddenly much more substantial, and the chances of water spreading over a bigger area is much greater

Fixing Bubbles On Exterior Walls

If the bubble has failed to disappear on its own as the water evaporates, you will need to break the bubble, and allow the wall to dry out.

After this, you will need to sand down the surrounding wall (making sure the water has not spread and caused other areas to become damp), and then repaint the section.

This can sometimes lead to a patchy finish; therefore, it may be necessary to sand down the entire wall, and start again from scratch.

Why You Should Fix Bubbles In Paint ASAP

The bubbles in your paint have been caused by moisture getting into and under the paint. This means that moisture is now sitting against the side of your home. This is never a good idea, as paint is designed to protect against this very thing.

Water on your walls can seep inside along cracks towards the interior walls where you can be plagued with mildew and damp. It can be hard to pinpoint where this is coming from, but areas of bubbling can be a cause if the problem is worse than you realise.

Damp exterior walls can also be prone to rotting if they are made of wood, and crumbling if they are masonry.

While the water trapped under the bubbles may seem insignificant, it is when these bubbles eventually crack and burst that the problems can really begin. The area exposed to the wet weather is suddenly much more substantial, and the chances of water spreading over a bigger area is much greater.

exterior paint bubbling after rain

Bubbling paint can be a common problem that occurs often through no fault of your own. If it does happen to you, it can be easily fixed, and you now know the best ways to prevent the same issue happening again in the future

Avoiding Bubbles After Rain

The clear answer to this is to never paint an exterior wall if rain is expected within the next 24-48 hours. However, there are a few other tips to prevent this and other similar paint issues, including the following words of advice:

● Try not to paint on a very hot day, as the heat from the sun can speed up the drying process, and cause adhesion issues.
● Never paint on a wall that is damp in any way.
● Always fix any problems that might be causing damp, such as: broken guttering, leaking pipes, or cracks in the walls or masonry.
● Use a primer that is waterproof to prevent moisture from leaking out of the walls.
● Take your time between each coat of paint to let it dry thoroughly, before moving on to the next coat.
● Choose a paint that is perfect for outdoor conditions, and that is not affected by rain or water.

Achieve Long-term Weather Protection With Hydrophobic Paints

If you want to avoid bubbling, cracking, peeling or flaking paint, you should choose a paint that is designed for exterior walls, and one which is resistant to water. A hydrophobic paint is the perfect solution, as it is waterproof while still breathable.

This means that any water that is still in the walls can evaporate without affecting the paint. These paints are highly resistant to uneven drying times, making them the perfect choice for our changeable British weather.

Hydrophobic paints are also long lasting (up to 15 years), and will maintain their good looks for the long-term, as water and dirt simply run right off the surface. You can find hydrophobic paints that are suitable for both masonry and wood.

The former is supplied as both a paint and a clear coating, to allow the traditional look of the brick to shine through. The latter can come in a variety of colours that are suitable for the natural exterior looks you want.

Don’t let damp problems ruin your weatherproofing resolve; invest in hydrophobic paint today, and actively repel water from the outset. Simply call 0800 1700 636, or, alternatively, click the button below to get started with your free site survey today!