Painting a garden wall, especially if it’s masonry, render, or brick, is something I do on a regular basis as a Professional Decorator. I thought I’d take the time to sit down and write a quick guide for anyone who is thinking about carrying out this type of work. I’ll keep it brief and simple.
There’s more to consider than you might think. Yes, you can get a garden wall looking good with a couple of coats of paint, but getting it to last is more complicated.
I’ll go through everything you need to know about how to paint a garden wall, including the considerations, the method, and the best paint for this type of work.
Why Painting a Garden Wall isn’t as Easy as You Think
The issue with garden walls is they don’t often contain a damp membrane, which means the water builds up behind the paint and forces it off over time.
The other issue is staining. Water stains from the masonry will often bleed through the paint, leaving horrible brown marks.
If you were to call Dulux Technical Services, they would advise you that you shouldn’t paint a garden wall at all. I don’t subscribe to that personally. There are a couple of things you can do to increase the longevity of your paintwork (mostly using the correct paint). Even then, just be conscious that you may need to repaint every 3 or 4 years to keep it looking good.
How to Paint a Garden Wall
Painting a garden wall is all about getting the prep right and using the best materials for the job. I’ll give you a step-by-step on the process you should take now, then I’ll et into more detail on the materials in a later section.
You will need the following
- Scraper.
- Paint brush.
- A long-pile roller.
- Paint Scuttle.
- Stabilising solution
- Masonry Paint
- Fungicidal wash
- Filler
Remove Loose Material
No matter how good your paint system is, if the existing paint system is failing, then so will the new. So, if your exterior wall is previously painted and is flaking, then you need to remove as much of it as possible.
Clean the wall
Paint won’t stick to dirt, so if your wall is particularly dirty, then you need to clean it. Pressure washing is the easiest way to do this, but you risk saturating the wall, so it isn’t ideal. Sometimes you can get rid of the dirt with a dry sweeping brush. Other times you might need a bucket of hot soapy water and a sponge.
Treat Algae
Algae growth needs to be treated before you apply any paint. Otherwise, it bleeds through your new paint and carries on growing. If you don’t see any green or red algae on your wall, then you can skip this step. If you do see algae, dilute a fungicidal wash with water, roll it onto the affected areas, and then leave it overnight.
Sheet up
I know it sounds obvious, but cover all the floor space in the area you’re working. If you’re using cotton sheets, then double up on the section closest to the wall to prevent paint from penetrating.
Stabilise
Any crumbly or chalky masonry on your wall needs to be stabilised. Equally, if you have removed flaky paint, then you also need to stabilise so the remaining paint doesn’t keep failing. If your exterior wall is already stable, then you can skip this step. Some masonry paints require a primer, which should be applied at this stage.
Fill Imperfections
Use a good-quality cement-based filler to repair holes and cracks. You should then wait at least 24 hours before applying paint.
Paint
Apply two thick coats of masonry paint to your garden wall using a brush and roller. Do this by cutting in the edges of the wall and then rolling the middle on each coat. Allow plenty of time to dry between coats.
Preparing a Garden Wall for Painting
Ask any decorator and they will tell you that prep is the most important part of any job. This is especially true when painting exterior walls. To prep a job like this, you should first remove any loose or flaky paint with a good quality scraper.
Imperfections such as holes, cracks and contours can be filled using Toupret Masonry filler. On a smooth wall you can fill as normal, then sand down until smooth. On a textured wall, it is often better to blend the filler in when wet, using a paintbrush.
Chalky or unstable masonry on your wall should be primed using a good quality stabilising solution. The one I use is Zinsser Peel Stop, which is water-based, can be recoated after a couple of hours, and creates the perfect base. Click here to see online prices.
Moss and algae needs to be treated to stop it from coming back or bleeding through your finished paint. You can pick up a treatment online by clicking here, which you apply to the affected area a day before you’re due to paint the wall, then just allow it to dry.
When prepping a garden wall for painting, one of the most important things is to let everything dry properly before applying the paint. If you remove any flaky paint, then the chances are the masonry underneath is damp. Leaving it a day or two to dry will give your new paint the best possible chance of adhering. Same thing if you apply fungicidal wash; allow it to dry fully before painting.
Click here for a more detailed guide on how to prep an exterior wall.
The Best Paint for a Garden Wall
There are two ways you can go when choosing the best paint for a garden wall. You can go for something very breathable like Emperor Paint, which will last longer because it won’t trap moisture.
Or you could go for an oil-based masonry paint, which isn’t as breathable, but has good adhesion and will block stains.
A lot of masonry paints claim to be breathable, but few are permeable enough to last on a garden wall. So, if you choose a masonry paint at random and hope for the best, the chances are you’ll be painting again a year later.
I’ll give you my product choices now.
Emperor Paints Masonry Paint
So, we’ve established that trapping moisture is the biggest problem when painting a garden wall. Emperor Masonry Paint is silicone-based, meaning it is highly breathable and won’t trap water.
It’s also hydrophobic, so it repels water and keeps your wall dryer for longer. This means that it’s more resistant to algae and doesn’t hold onto dirt as much.
Emperor Masonry Paint will last longer than any standard paint on a garden wall, but it is expensive.
Sandtex 365
This is an oil-based masonry paint. If you’re going to go for an oil-based paint, then choosing a good product isn’t as important, but I wanted to talk about the best option on this blog.
Oil-based isn’t as breathable as water-based, but it does block stains, and a lot of Decorators swear by it. I’m sceptical, just because I think flaking paint is more of an issue than staining.
However, if stains are what’s on your mind, then Sandtex 365 will stop them dead on a garden wall. The opacity of this paint is bob on, as is the finish.
More Tips for Painting a Garden Wall
Use a stiff paint brush
Use a stiff paint brush with synthetic bristles. If you use a soft paint brush, then the paint will pool on your cutting in, and it will be harder to work the paint into the crevasses on the wall.
Opt for a long-pile roller
A long-pile roller like a Purdy Colossus is more suited for this type of job. You’ll find it spreads a generous coat and follows the contours of the wall.
Dilute your paint
This depends on which paint you’re using, and you should always check the manufacturer’s instructions, but diluting your paint slightly will make it easier to apply. This is particularly true when using oil-based paint.
Keep a ‘wet edge’
This isn’t as important on your first coat, but it is vital on the second. It’s good to keep a wet edge when you’re painting a garden wall. Work on one section of wall at a time, cut in, then roll that section before your cutting in is dry. Then move onto the next section and repeat the process.
FAQs
How do you seal a garden wall before painting?
You only really need to seal a garden wall before painting if it is chalky and unstable, in which case you should use Zinsser Peel Stop. Otherwise, follow the instructions on the product that you’re using to paint it with. Some recommend a specific primer, and others don’t need priming at all.
Should you pressure wash garden walls before painting?
Pressure washing is good for a couple of reasons, but it does have one major drawback. On the plus side, it cleans the wall and removes any flaky paint. But the downside is that it will saturate the substrate, and moisture is always a concern when painting a garden wall.
Can you use PVA to seal a garden wall before painting?
PVA causes more problems than it solves in decorating (even though many water-based paints contain PVA as part of a copolymer). If you use PVA to seal a garden wall, then you may encounter crazing or adhesion issues with your paint.
Can you paint a damp garden wall?
A garden wall needs to be as dry as possible before you paint it.
0 Comments