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3 Simple Ways to Stop Sand Washing Out of Block Paving Joints

In this post, we look at how to stop sand from coming out of block paving.

When you first lay paving blocks, you probably expect your sand to stay put. So, why is it suddenly washing away? Is the sand not good enough – or am I doing something wrong?

It’s actually a more common problem than you might think. So, we’ve decided to show you how to stop sand washing out of block paving for good.

There are three ways you can keep sand from spilling out of your block pavers. That means either sealing up, layering in a compound, or topping back up again with sand. All these options work wonders, but the difference lies in the cost.

Keep reading, and you’ll find out how to:

  • Seal your blocks/paving
  • Rejoint using a compound
  • Keep topping up with kiln dried sand

It might not occur to you that the sand in your joints is at risk of sweeping away. In which case, it’s time to read on and get clued up!

Why Your Paving Loses Sand

Over time, patio sand can wash away due to its continuous exposure to different types of weather, including rain, wind, snow, etc. Using a pressure washer on your jointing sand as you clean your blocks can also blast it clear.

That’s not to say that it’ll spill out from the get-go. This problem will likely take years to become an issue, but it’s still worth keeping a close eye on.

Why secure your paving sand?

You need to keep your paving sand tight and compact – here’s why.

  • Through constant weather and pressure washing, it’s going to disperse.
  • That means more instability and more chance of weeds growing.
  • Sand repels mould, moss and mildew from growing in damp spots.
  • It’ll keep your blocks’ surface level and will therefore prevent sinking.

How to Stop Sand from Washing Away – 3 Surefire Solutions 

1) Seal the block paving

The number one way to keep sand from washing out of pavers is to seal the area. This is your best shot at making sure your pavers and joints stay tight and protected for years to come. We recommend you always get your joints sealed as soon as the blocks are laid. This will give the joints a tightness akin to concrete – its maximum resistance to weather, washing, you name it.

Water is simply going to bounce off, meaning your compacted sand holds in place and won’t get washed away.

Cost of professionally sealed block paving 

Generally, you can expect professionals to charge £10 per square metre to seal your paver surface. Or, you can pick up a bottle of sealant and do it yourself for less than £40. Prices are always going to vary, of course, so grab two or three quotes.

How To Seal Blocks Yourself 

Purchase a top-rated block paver sealer from Amazon or other DIY retailers and carefully follow the instructions on the bottle. Make sure you’ve cleaned up the paved area, there is no rain forecast and that it is completely dry before you start to seal, too!

2) Rejoint using a more expensive jointing compound

Jointing compounds are popular, but they are usually an expensive option. However:

  • They’re dead easy to set with a bit of water.
  • They won’t stain your pavers.
  • They prevent weed growth. 
  • They’re extremely low maintenance – you get what you pay for.

How To Use 

Make sure your pavers are evenly laid, and make a point of moistening the surface. Get the area clear of weeds and dirt, and brush your compound into the joints. Then, use a soft brush to get the excess out, leave to harden for up to a few hours. Job done!

Average Price

Paving jointing compound from GEO-Fix will set you back over £30 on Amazon, and a 20kg bag of No Grow should cost around the same – likely worth the extra pennies if you ask us.

Best Brands To Buy 

Top compound brands include:

3) Keep Topping up With Kiln Dried Sand 

Topping up with kiln dried sand can be a bit of a chore, but it gets the job done. It’s going to mean ongoing maintenance from you, though the odd sweeping in of more sand is probably going to be cheaper than, say, using a compound.

Why use kiln dried sand?

It’s great for brushing into cracks and for simple home use. All you need is a stiff brush, a bag of sand, and away you go. Affordable, easy to find, and no need for professional help.

How much sand to use 

Generally speaking, 25 Kg of sand should cover about 30 square metres of paving area. You won’t need more than that for an average patio.

How do I re-sand block paving?

If you want to replace your block paving sand, start with cleaning and clearing the entire area. Get rid of weeds, dirt and debris with simple brushing, and gently pressure wash anything remaining.

Leave it to dry completely – overnight is a safe bet – and then prepare to start brushing in your re-jointing sand. Follow the instructions before you have the right materials for the best results.

The only thing you really need to focus on here is getting your sands right into all the nooks and crannies. Miss a bit, and it’s at risk of getting washed away, or you’ll knock a few years off the protection.

Dangers of Regular Pressure Washing 

Regular pressure washing and re-sanding might not seem like a problem, but it’s going to cause instability in your driveway or paved area. Blasting out compacted sand and topping back up is going to create sinking or wobbling conditions over time. That’s why, no matter the paving sand or bricks in use, it’s crucial to protect your blocks first and then wash carefully every few days.

Here is our guide on power washing block paving correctly so you don’t lose too much sand.

FAQ’s 

Does kiln dried sand go hard? 

Not on its own. Kiln dry sand will compact when wet; however, you will need to seal the fine sand in between the paving slabs for it to truly go hard.

How do you harden joint sand? 

To harden jointing sand, you’ll ideally need to use a paving sealer, concrete or cement (the latter two can get pretty messy). Water’s only going to do so much.

Can you sand block paving wet?

No – you should always wait for dry weather to roll around. Professionals may use heat torches to dry off rained-on paving slabs quickly, but for DIY, patience is recommended.

What’s the best sand for block paving? 

Kiln-dried sand is the best paving joint sand – it’s the best at keeping water out and for keeping your blocks tight. Other fine sands, sharp sand, and building sand have different purposes elsewhere – they won’t work here.

How long does block paving sealer last? 

It varies on the make, but you can expect some paving sealers to protect you for up to ten years after application.

Where can I buy patio sand? 

Paving sand is readily available online or check out your local B&Q, shop directly with brands such as Sika, or take a look at the best kiln dried sand Toolstation has in stock.

Last Word 

Knowing how to keep sand between pavers is key to the longevity of your paving. Ultimately, you’re going to need to make sure you’re using kiln dried sand for the gaps in your block paving. Beyond that, you should think about using a paver sealer or a compound to lock it all in.

The other option is continuing to top up the sand whenever it spills up and out over the blocks. That’s a never-ending process, one that’ll begin again and again. Cheap, yes – but sealing kiln dried sand is the best way forward if you really don’t want the hassle or cost.

Follow this process and you’ll stop sand getting washed out of your joints every five minutes. Not only that, but sealers will prevent weeds, resist water erosion, and will protect the surface against cracks and rain damage.

Try our top tips above, and check out top kiln paving sand and sealer products at your local DIY shops. It might not seem important, but stop sand getting washed out now and you’ll add years to your driveway or patio lifespan.