How to Repoint Patio Slabs: A Simple DIY Guide (With Photos From a Recent Customer Job)

Patio pointing might not be the most exciting garden project, but it’s one of the best ways to improve the appearance of an ageing patio and prevent further damage.

Recently, I was hired by a local customer in Newquay to tidy up the pointing between their patio slabs. Over time, the original mortar had cracked, become loose, and started to wash away, leaving gaps between the paving.

In this guide, I’ll show you exactly how I repointed the patio, the tools I used, and some professional tips to help you achieve a long-lasting finish.

Why Patio Pointing Fails

Patio pointing is exposed to everything the British weather can throw at it.

Over time, frost, rain, foot traffic, weeds, and natural movement in the slabs can cause the mortar joints to crack and break apart.

Common signs your patio needs repointing include:

• Cracked mortar joints
• Loose or missing pointing
• Weeds growing between slabs
• Water collecting in the joints
• Patio slabs beginning to move

If caught early, repointing can restore the patio and help prevent more expensive repairs later.

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Tools and Materials Needed

For this project I used:

• Stiff bristle brush or yard broom
• Soft bristle brush
• Flat-head screwdriver
• Pointing trowel
• Mortar finishing tool or brick jointer
• Spray bottle
• Bucket
• Sharp sand
• Cement

Optional:

• Angle grinder with mortar raking blade
• Knee pads
• Dust mask
• Soft hand brush

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Step 1: Remove Loose Mortar and Clean the Joints

The first stage is preparing the patio.

Using a stiff brush and flat-head screwdriver, remove all loose mortar, dirt, weeds, moss, and debris from the joints.

If the existing pointing is particularly stubborn, an angle grinder can speed up the process. Just be careful not to damage the edges of the paving slabs.

Good preparation is the key to a successful repair.

How Much Mortar Should Be Removed?

As a general rule, remove mortar to a depth of at least:

15-20mm or roughly twice the width of the joint.

Many professionals recommend a minimum depth of 15mm for a durable repair.

If you only remove a few millimetres of mortar, the new pointing may not have enough material to properly bond and could fail prematurely.

For my customer’s patio, I aimed to remove all loose material and achieve a consistent depth throughout the joints.

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Step 2: Mix the Mortar

For traditional patio pointing, I use a simple mix of:

4 parts sharp sand
1 part cement

Add only a small amount of water.

The mortar should remain relatively dry and crumbly, but when squeezed in your hand it should hold together.

This is sometimes referred to as a “semi-dry” mix.

Too much water can cause shrinkage and cracking as the mortar cures.

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Step 3: Push the Mortar Into the Joints

Using a pointing trowel, carefully place mortar into the gaps between the slabs.

Work in small sections and make sure the mortar is fully compacted into the joint.

This is probably the most important part of the job.

Any voids or air gaps can allow water to enter, which may lead to frost damage later.

Take your time and firmly compress the mortar as you go.

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Step 4: Compact and Finish the Joint

Once the joint is filled, use a pointing tool to compress and smooth the mortar.

A brick jointer works well, but you don’t need specialist tools.

For this job, I used a simple piece of ½-inch pipe, which created a neat, consistent finish throughout the patio.

The aim is to compress the mortar firmly while creating a smooth, professional-looking joint.

Top Tip

Don’t rush this stage.

Properly compacting the mortar improves both the appearance and durability of the pointing.

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Step 5: Brush Away Excess Mortar

Before the mortar fully sets, use a soft brush to remove any loose material from the surface of the paving slabs.

This helps prevent mortar staining and leaves a much cleaner finish.

Be gentle and avoid disturbing the fresh joints.

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Step 6: Lightly Wet the Mortar

One trick I’ve used for years is lightly misting the finished pointing using a spray bottle.

The aim isn’t to soak the patio.

Instead, apply enough water to dampen the mortar and encourage proper curing. I find that the mortar soaks up the water quickly. Spray just enough to see a little pooling, then stop.

This helps:

• Reduce rapid drying
• Improve strength
• Reduce cracking
• Produce a more durable finish

During hot weather, it can be worth lightly misting the joints again later in the day.

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The Finished Result

After cleaning and repointing the entire patio, the transformation was impressive.

Fresh pointing instantly makes paving look newer, cleaner, and much better maintained.

For my customer, it was a relatively small repair that made a huge difference to the appearance of their garden.

Before and after on these steps:

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Professional Patio Pointing Tips

Here are a few tips I’ve learned from experience:

Don’t Work in Heavy Rain

Fresh mortar can wash out before it has a chance to cure.

Avoid Very Hot Days

Mortar that dries too quickly can crack.

Use Sharp Sand

Sharp sand produces a stronger mix than soft building sand.

Keep Joints Consistent

Uniform joint depths and finishes always produce a better result.

Clean As You Go

Removing excess mortar before it hardens saves a lot of cleaning later.

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Final Thoughts

Repointing patio slabs is a straightforward job that most DIYers can tackle with a few basic tools and some patience.

The secret is preparation, proper joint depth, and taking the time to compact the mortar thoroughly.

If your patio is looking tired, loose, or overgrown with weeds, fresh pointing can dramatically improve its appearance and extend its lifespan for years to come.

If you’re local to Newquay or the surrounding Cornwall area and would prefer a professional finish, feel free to get in touch through HandymanBen.com.