How to Prepare Exterior Surfaces for Long-Lasting Paint

Step 1: Start with a clean surface

Before anything else, your surface needs to be clean.

Dirt, grease, algae and loose debris can all stop paint from bonding properly, so it’s important to remove them completely.

For most exterior surfaces:

• Use a stiff brush to remove loose dirt
• Wash down with warm soapy water
• For tougher areas, use a suitable exterior cleaner
• Rinse thoroughly and allow to dry fully

Pay particular attention to areas exposed to moisture, such as north-facing walls, where moss or algae can build up more easily.

Step 2: Remove loose or flaking paint

If your surface has been painted before, check for any signs of peeling, cracking or blistering.

Any loose paint will need to be removed before repainting, otherwise your new finish won’t adhere properly.

To do this:

• Use a scraper or wire brush to remove flaking paint
• Sand the edges to create a smooth transition
• Wipe away dust before moving on

This step helps create a stable base for your new paint, ensuring a more even and professional-looking result.

 

Step 3: Repair and fill imperfections

Exterior surfaces aren’t always perfectly smooth, and that’s okay. But larger cracks, holes or damaged areas should be repaired before painting.

Look out for:

• Cracks in masonry
• Gaps around frames
• Small holes or surface damage

Use an appropriate exterior filler to repair these areas, then allow it to dry fully before sanding smooth.

Taking the time to fix these details will help your finished surface look cleaner, sharper and more considered.

 

Step 4: Sand for a smoother finish

Sanding might feel like an extra step, but it can make a noticeable difference.

It helps:

• Smooth out rough areas
• Remove any remaining loose material
• Create a slightly textured surface for paint to grip

You don’t need to sand everything back completely; just focus on uneven areas, previously painted surfaces and places where repairs have been made.

Once done, remove any dust with a clean brush or cloth.

 

Step 5: Prime where needed

Not every exterior surface needs a primer, but in some cases, it’s essential.

You should consider priming if:

• You’re painting bare wood or metal
• The surface is particularly porous
• You’ve made repairs with filler
• You’re making a significant colour change

A primer helps create a consistent base, improves adhesion and ensures your topcoat looks even and true to colour.

 

Step 6: Choose the right conditions

Even with perfect preparation, timing matters.

Exterior paint performs best in dry, mild conditions - not too hot, not too cold, and definitely not wet.

For best results:

• Avoid painting in direct, intense sunlight
• Don’t paint if rain is expected
• Check temperatures (typically above 8-10°C is ideal)
• Allow enough drying time between coats

Planning your project around the weather helps ensure your hard work pays off.

 

Step 7: Use a paint designed for the outdoors

Once your surface is fully prepared, the final step is choosing a paint that’s built to last.

Exterior paints need to do more than just look good; they need to protect. That’s where Sandtex® comes in.

Designed specifically for exterior use, it offers:

• Long-lasting protection against the elements
• Resistance to cracking, peeling and flaking
• Strong colour retention
• A finish that stands up to the British climate

From front doors and garden walls to masonry and outdoor features, using the right paint helps lock in all the effort you’ve put into preparation.

Preparing your exterior might take a little extra time, but it’s what makes the difference between a quick refresh and a finish that truly lasts.

By cleaning, repairing and priming your surfaces properly, you’re setting the foundation for colour that looks better, performs better and stays looking its best for longer.

So, whether you’re planning a full exterior update or a simple weekend project, start with the prep and let your colour do the rest.