Is there anything more deflating than spotting a bubble forming on your freshly painted wall? It can happen within hours of you putting down the paint brush. Sometimes that annoying bubble appears days, months or even years after decorating. But why?
Paint bubbling is actually one of the most common decorating problems. It's almost always fixable too, you just need to work out what's causing it first. Don’t be tempted to simply paint over a bubble. You need to understand why it's there or you’ll end up having to repaint yet again. So before you reach for a scraper, let's look into what's actually causing that blistering paint in the first place.
What is paint bubbling?
Paint bubbling is exactly what it sounds like. It’s small raised air bubbles, blisters or hollow patches that appear in your paint.
Underneath each bubble, the paint has lost its grip on whatever’s beneath it. Be that bare plaster, an older layer of paint or the wall itself. Basically, the bubble shows that something’s broken the bond between the paint and the surface underneath. Usually, it’s air or moisture as it tries to escape or expand; it pushes the paint layer up and away. That lifted paint can crack, flake or peel away.
What are the causes of paint bubbling on walls?
There are three main culprits behind paint blistering or bubbling. When you know which one you’re dealing with, you can work out how to fix it.
Trapped moisture and damp
This is the most frequent cause. It’s particularly common in the older, poorly insulated houses that many of us live in here in the UK.
As our period property expert, Roger, explains, “Older properties were built using traditional, moisture-permeable materials, meaning they were designed to help the building to breathe. Using non-breathable materials like modern plaster or conventional vinyl paints trap moisture in the wall and cause unsightly bubbling and peeling paint.”
Roger advises, “Instead, opt for breathable materials such as lime plaster and use a highly breathable paint like our Claypaint, which allows the walls to release any excess moisture without affecting the fabric of the building.”
If you’re keen to learn more, our guide to the tell-tale signs there's damp in your walls is well worth a read.
Poor ventilation and condensation
Bubbling and peeling paint can also be caused by condensation, which is the result of poor ventilation. Modern homes are often sealed tightly; double or triple glazing, cavity wall insulation and loft insulation all help conserve heat, but they can trap moisture inside too.
Steamy rooms like kitchens, bathrooms and laundry rooms are particularly prone to this. Signs of condensation include water droplets appearing on walls and windows, damp patches and even black mould. You can avoid this with good ventilation, extractor fans and a dehumidifier if necessary.
Also, check for plumbing leaks, which can cause condensation problems and damp walls.
Lack of preparation or poor application
We’re sorry to say, but the paint bubbling can be down to your lack of preparation before decorating. We know no-one likes the prep, but it’s the most important bit!
Painting over dirt, grease or old wallpaper paste stops proper paint adhesion. It means paint dries on the surface without ever really bonding to it. New plaster is another common trigger; it's naturally porous, so it needs a mist coat, primer or stabilising product first. If you skip that step, the plaster can pull moisture out of the paint too quickly, which causes it to lift as it dries.
Don’t forget to allow proper drying time between coats to let moisture evaporate and the paint dry thoroughly. If you rush this stage, you may find adhesion problems and bubbling, this is made even worse in humid conditions.
Find out more about why your paint may be bubbling and peeling
How can I fix paint bubbling on my walls?
It pays to take your time to get this right. Follow our step-by-step process to fix your blistering paint.
1. Identify the cause: This step matters. Fixing the visible bubble without addressing its cause almost always means it’ll return. Gently press on a bubble and scrape away a small test area. If the paint lifts back to bare plaster or drywall, moisture’s likely to be the problem.
If the bubble sits between layers of paint and the surface beneath feels solid and dry, preparation or application is your likely culprit.
2. Scrape away all loose and bubbled paint: Use a scraper or putty knife to remove every trace of lifting paint. Work back to a firm edge, where the paint’s still properly bonded. Any old paint left behind will result in poor adhesion, which means the bubbles may return.
3. Sand and smooth: Be sure that surfaces are wiped down and given a light sanding where necessary. Smooth any rough edges with sandpaper, but don’t go too aggressively into the plaster itself.
4. Fill any dents or hollows: You may find dents, cracks and hollows once you’ve scraped back the bubbled paint. Fill these carefully, keeping the filler flush with the surrounding wall. Sand lightly once it’s cured to ensure a flat, even surface.
5. Clean the wall thoroughly: Dirt, dust, grease or residue can stop new paint bonding well. This is often the case in kitchens and bathrooms where there can be a build up of oil or grease. Apply primer, like our Isolating Primer, on oil and grease stains. Make sure to give it plenty of drying time.
6. Prime the wall: On powdery surfaces, use our breathable Wall Glaze or Bonding Primer to stabilise the walls before painting. Freshly plastered walls need a diluted mist coat of paint and plenty of time to cure fully before decorating. Your plasterer can advise on how long that should take.
7. Repaint carefully: Choose a highly breathable paint (such as Claypaint), especially if excess moisture was behind the paint bubbling. It lets any moisture in the wall escape naturally rather than building up.
Stirring the paint vigorously can cause air bubbles. Take it slowly. Don’t overload the paint roller. Apply thin, even layers of paint and make sure the room’s well ventilated as it dries.
It’s also important to avoid painting in high humidity, direct sunlight or extreme temperatures. All of those factors can affect the outcome.
Your paint bubbling FAQs
Can I paint over bubbled paint?
No, not successfully. Painting straight over a bubble might hide it for a little while, but the trapped air or moisture underneath is still there. It’s likely to push through again and it’ll often take that new coat of paint with it. We recommend you always scrape back, prepare properly and repaint the area. Don’t simply cover up the problem.
What is the best paint for damp walls?
A highly breathable paint is the best long term option for damp-prone walls, particularly in older UK properties. Breathable paints, such as our Claypaint, let moisture within the wall escape naturally.
Breathable paint isn’t a cure for a serious, ongoing damp problem on its own. That needs addressing before you apply paint.
Do paint bubbles go away when dry?
Unfortunately not. A bubble that appears while paint’s drying is a sign of poor adhesion in that spot. It won't reattach or flatten out on its own once it’s dry. Left alone, most bubbles will eventually crack open and start to flake. It's much better to address them properly, following the steps above.
Does paint bubbling always mean damp?
Not always, but it's one of the most common causes. That’s particularly true in older homes. Bubbling can also be caused by poor ventilation and condensation. Or it could be that paint’s been applied to a dirty, greasy or unsealed surface. The best way to tell the difference is to scrape back a small bubble and look at what's underneath. Damp plaster indicates moisture. A solid, dry surface points to preparation or application issues instead.
If you're unsure, our guide to tell-tale signs there's damp in your walls covers what to look out for. It'll help you rule damp in or out with more confidence.
