Damaged plaster on an interior wall

Why Is My Plaster Bubbling?

25 January 2022

If you have noticed that the plaster inside your property has started to bubble, this is obviously a cause for concern. The question though is often not just why is my plaster bubbling, but what can I do to stop that same plaster from bubbling at all?

So, to help you out and give a better idea about what can be done regarding bubbling plaster in your home we have put together this short guide that will hopefully help you understand and remedy your own problem.

Why Does Plaster Bubble?

The main and often sole cause of plaster bubbling is having damp walls. The reason that the plaster bubbles is because the moisture present within the wall has risen to the masonry’s surface, and has come into contact with the plaster covering the brickwork.

As the moisture comes into contact with the plaster, the plaster bubbles up and rises off of the wall that it has been adhered to. Then, if left long enough, that plaster will crumble and fall, collecting around the base of the wall as a form of dust.

Simply put, the bubbling in your plaster is down to moisture escaping the brickwork of the wall itself, pushing plaster up and ruining that plaster as a result. It’s an annoying problem, and one that should be taken very seriously; Not because the plaster is valuable, or annoying to replace, but because the bubbling of plaster indicates that your property is suffering from damp, a critical property care issue that must be resolved.

How to Stop My Plaster from Bubbling:

Your plaster bubbling off of the wall it’s been applied to is a problem, but not one that can be sorted by chiselling the plaster off and re applying the plaster fresh. In fact, in this situation removing and then applying a fresh coating of plaster is almost literally papering over the problem.

Instead, you should look to treating damp walls internally before even tackling the plaster situation. There are a few different ways in which damp can enter your walls, but until the reason for the damp has been found and addressed you are going to keep suffering from bubbling plaster.

So, why might your walls be suffering from damp and causing your plaster to bubble?

Rising Damp

rising-damp-on-walls

Rising damp is a form of damp that is brought about from a specific type of building material failure. In situations involving rising damp, the damp proof course (or DPC) of a property has failed (or been improperly installed), and as a result moisture is now able to make its way into your properties walls.

The way that water manages to enter your properties walls following the failure of a damp proof course is through a process called capillary action. Capillary action is when moisture is drawn into the masonry of a property, and travels upwards through channels in the mortar and brickwork, where it turns to damp in the properties walls.

It can be easy to spot rising damp in a property – it literally rises up in the wall from ground level, and won’t rise higher than around a meter off of the floor. The fact that it doesn’t rise too high shouldn’t let you think that it is any less dangerous, however. Rising damp is still damp, and still capable of bubbling and ruining your plasterwork, as well as underfloor joists, skirting boards, floorboards, wallpaper, and whatever else might have come into contact with the rising damp.

Rising damp can only be stopped by a damp proofing technician, who (following a survey to ensure that the issue is rising damp) will install a fresh DPC in your property to stop the capillary action from taking place.

Once that DPC has been installed, the walls will be able to dry out safely, and you will be able to remove and replace the plaster on the affected walls. You will also be able to undertake any other repair work that has to happen, such as floorboard repair.

Remember, only apply your plaster to the wall again once the underling damp issue has been resolved, otherwise you will only find yourself in the exact same situation the next time it rains and there is moisture present in the ground to travel into your property!

Penetrating Damp

Penetrating damp on a wall

Penetrating damp is another form of damp that appears in a property thanks to a failure within building materials – however, the definition of the actual building materials that have failed in the cases of penetrating damp is much broader and looser than in the case of rising damp.

Any type of failure in a property that leads to an onset of damp constitutes penetrating damp. If your guttering is clogged, for example, and the clog causes rainwater to cascade down the side of your property, that pouring water can easily destroy paint, set in your walls, and over time cause a damp problem to set in.

That kind of problem can crop up out of all kinds of different issues – drains that won’t drain, failed lintels allowing moisture to enter around a properties windows, cracks in exterior walls allowing for rainfall to enter the properties masonry – all forms of penetrating damp, and all problems with slightly different remedial work needed to fix them.

However, they will need to be fixed. As far as the particular remedy needed to put a stop to the penetrating damp in your property, you can rely on the services of a damp surveyor to correctly identify not only the cause of penetrating damp in your property, but also to deliver to you a proposed remedy to the damp itself, which a qualified damp proofing technician can carry out.

Once the work has been completed on your damp proofing, you can look to start repairing your properties interior. This includes replastering, and replacing the plaster that has bubbled up as a result of the penetrating damp.

Condensation

Condensation running down a window

Condensation is another way that damp can get into your walls, however, condensation isn’t a product of a building material failing, rather the outcome of everyday life and the choices you make.

One example of condensation easily turning into damp within a properties walls is found in the bathroom. If a shower creates a lot of steam and hot, moist air with nowhere for that same condensation to go, then its almost inevitable that the humid air is going to come to rest on the bathrooms walls as condensation.

The same goes for any hot air created in a property that has no place to ventilate to – that warm, humid air will often be drawn towards a properties walls thanks to the difference in pressure between the interior and exterior of a property.

On contact with the cooler interior walls of a building, that same warm moist air will revert back to a liquid state. That’s the process of condensation being formed, and it can come from the likes of a shower as mentioned already, or perspiration, cooking, drying clothes, plants – pretty much anything that gives off moisture as a by-product of its being.

If condensation keeps being created and collecting in the same spot over and over, then its likely that damp will set in as a result. This damp is different to other forms in that moisture is making its way into the masonry from the interior of the property, rather than from the more likely option of moisture spreading out from within the masonry itself.

This means that you are likely to notice that your property has a problem with condensation before it sets within your wall, as you will see that condensation sat on top of your plaster and possibly affecting the same plaster long before it becomes full fledged damp.

However, this does still mean that you need your condensation issues sorting, as that condensation can still cause your plaster to bubble – it’s just that you may be able to avoid full damp proofing treatment if you act early enough.

Taking steps to reduce condensation should be your first priority if it is condensation causing your plaster to bubble. This means increased ventilation through the likes of an extractor fan or a positive pressure system, and being more mindful when it comes to your behaviour to keep condensation levels down.

Once you are confident that your property has had its condensation issues rectified then you will be safe to begin repair work on any affected plaster your property might have. Remember; bubbling plaster might not be the only form of damage the condensation has wrought. You might also notice curling wallpaper, cracked paint, or even black mould as a result of condensation.

If you aren’t sure if your property is suffering from condensation based problems, or you want to be more informed on how you can stop these issues in the future then please don’t hesitate to contact our team for more information.

How to Repair Bubbling Plaster

If you have sorted out the issue within your walls that has caused the plaster to initially bubble then you will be in a position to begin fixing that same plaster. It could be that you want to take all of the plaster off of the wall, and start from scratch.

In some situations that may well be advisable – the scope and extent of the damage that the damp causing the initial bubbling could be widespread, and replastering entirely might be a good idea. In these situations, its always a good idea to call in a trained professional who can complete the plasterwork properly, with a high degree of skill and to a standard you find acceptable.

The same could be said for touching up walls that have only had minor bubbling in the plaster itself. Even though only a small section of the wall has been affected and needs to be cleared, it could still be preferable and potentially better contacting a trained plastering professional to restore the wall to its former state.

Usually, the plasterer will follow the steps described below when it comes to removing and restoring bubbling plaster:

Step 1

First, the bubbling plaster will be removed entirely from the wall. This newly cleared space will have its edges checked for other forms of contaminated, damp or damaged plaster, and if more is found, then more plaster will be cleared away.

Step 2

Usually, the wall will be cleared until a hard, stable, undamaged layer of plaster is revealed, or until the masonry is exposed. Once that has been achieved, the newly uncovered surface will need to be cleaned. This is usually done with a nylon brush that’s stiff enough to clear away building debris, as well as a sponge with some clean water to clean away any deposits of lime that have built up as a result of the damp.

Step 3

Once the walls are clean it will be time to apply a coat of primer. The primer is used to contain any residue on the wall from the previous damp from spreading, and it also helps to achieve proper bonding with the plaster compound that will be applied to the wall itself.

Step 4

One the primer has dried off, the missing plaster can be repaired and applied. This usually means that a patching plaster will be applied – or if the area that is being treated is small enough, a jointing compound could be used. The actual amount of coatings that will be needed depends entirely on the depth of the hole left from removing the damaged plaster.

Step 5

Once all the coatings have been applied to the wall and the plaster has been smoothed out to lie flat against the rest of the plaster, it will need to be sanded just to smooth the wall surface properly. This is usually followed by a quick dusting with a damp cloth to make sure the wall is clean, and that any dust wont be trapped by the primer.

The primer is an essential step in the re application of plaster because it stops any residual water damage that might be in the walls from effecting the newly applied plaster. Once that primer has been applied then you can look to redecorating the wall in whatever you see fit, as the process will be complete.

Replastering Your Walls

If you have noticed that your plaster has started to bubble and you would like to seek out professional help to get the underlying damp fixed, then contact one of our damp surveyors today to begin the process. Call 0800 288 8660 or get in touch with us online today to learn more about our damp proofing services, and how we can help your walls get back into order.