Pressure washing block paving.

How to clean block paving with a pressure washer.

Pressure washing block paving using a rotary head cleaner Do you want to correctly learn how to clean your block paving with a pressure washer? Pressure washing block paving seems a simple task but it can do long term damage to block paving if not done correctly.

We have provided a free guide with tips and good advice on how to clean your block paving with a pressure washer.

We have also included plenty of best practices that professional cleaning contractors use. They are worth reading before you begin to clean your block paving driveway or patio.

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Tips to note before you begin to clean your block paving with a pressure washer

  • Always begin by giving your block paving a good sweep. Use a stiff broom to remove any debris such as stones, old cement and general loose dirt. This stops the debris becoming a projectile when hit by the jet of water. It also stops it having an abrasive effect on your paving blocks. It also allows you to fully inspect your paving before you begin pressure washing your block paving.
  • Look for any oils stains that need removing. Apply a cleaner to any oil, petrol and grease stains on your block paving surface before you clean your paving. This makes it easer to remove the stain with a pressure washer. Remember any untreated stains will show up once your paving is cleaned.
  • Think about applying a cleaner first before you use a power washer. This will make it much easier to remove the dirt from your paving surface. You could use bleach to remove the dirt or why not consider using a more environmentally friendly cleaner such as an apply and leave paving cleaner. After you have cleaned your paving blocks why not consider applying one of these cleaners. They kill all your moss & algae spores so stop greenery re-growing for up to 6 months afterwards. They also help keep your paving cleaner for longer.
  • Does any of the block paving need to be relaid because it has sunk? This could be done after you wash your block paving or before. It’s up to you. We have a helpful guide on relaying sunken block paving here.
  • Consider applying a weed-killer a few days before you clean your block paving with a pressure washer. After you have applied a weed killer to the weeds, moss and algae wait until the weeds and moss show signs of being dead. You can tell when your moss or weeds have died because they will become brown and dry. When moss and weeds on your patio or driveway are dead it makes them so much easier to remove them from the block paving, either by hand, using a weed removal tool or using the jet washer to remove them.
  • Consider using a rotary head attachment to contain the water jets and stop splashes. These attachments for your pressure washer are ideal if cleaning in a confined space or if you are close to your neighbours home.

Step-by-step guide on how to clean block paving with a pressure washer.

  1. Begin by starting in a corner above the run off area of the dirty water. This is so that you don’t have dirty water running on to your cleaned area of paving.
  2. Always power wash the driveway or patio working away from, and not towards buildings, cars and neighbours property unless unavoidable.
  3. Work your way with the power-washer across the paving trying to avoid splashing any doors and windows with dirt. If you do get them dirty make sure you clean up by rinsing down as you go. Therefore not having to go back and clean them afterwards.
  4. Remember to rinse down house and garden walls that will be splashed with dirt as you clean your paving. If you want to avoid splashes when pressure washing block paving why not consider fitting a rotary head cleaning brush to the end of your lance. These work by stopping splashes because the jets of water are contained within the housing of the head.
  5. Work in gentle sweeps across the paving. Pay attention as you go that each area of paving is cleaned evenly. You don’t want to be left with ‘tiger stripes’ when you’re paving has dried. This is often the case if you use a low powered jet washer. Or if a cleaning liquid has not been applied to heavily soiled and dirty paving beforehand.
  6. If you’re paving was very dirty you will have a lot of dirt that needs to be cleaned up afterwards. Often you can rinse the dirt into a drain or grassed or soiled area. But remember that if you are pressure washing your paving towards a public highway, you will need to make sure the pavement and road are also washed or swept afterwards to remove the dirt.
  7. Once the block paving is clean you need to allow to dry. Once dry re-sand any areas that will have lost jointing sand between the paving blocks when they were cleaned. This is essential to maintain the structural strength of the block paving.
  8. Once finished, re point with cement any areas of pointing that may have come loose.
  9. Now your block paving is clean, keep it clean for longer by applying an apply & leave cleaner.
  10. That’s it, you’re done! You’re now an expert in pressure washing block paving.

Other things to consider when using a pressure washer to clean your block paving

Try to avoid deep-down joint sand loss?

Loss of deep-down joint sand in block paving allows water to penetrate the sand below leading to your paving sinkingThe jointing sand gives the paving bricks their locking together strength. The sand will be lost by being ‘blown out’ by the strength of the jet of water if used to clean your paving at close range. This is often the case when using a pressure washer to remove weeds and moss.

“But I will replace the joint sand later” I hear you say. Well if you remember when you’re paving was laid, the contractor would have used a whacker plate compactor. He used this to not only compact the paving but to also force the kiln dried sand into the joints of the paving. This action locks the individual brick pavers together. You can replace this dry sand yes, but you don’t compact your paving again after each clean to lock the block paving together again.

Eventually the individual bricks will become loose because the sand replaced is weak and light because of non compaction of the paving around it. This leaves your paving prone to sinking because of a loss of the sand that gives strength to the structure of the paving. Especially if not replaced in the joints between the bricks. It also allows rain water to penetrate the paving joints easier which in turn leads to the sub base becoming soft.

Try not to over-use your pressure washer to clean your block paving

If possible, try not to become addicted to cleaning your block paving with a pressure washer. Try using a paving cleaner or weed killer first to kill weeds and remove ingrained dirt. Pressure washing block paving should be used to gently clean and rinse the surface. It should not used to blast the paving clean at maximum power & force.

Use the pressure washer lance at an angle

The lance of the pressure washer should be held at an angle so not to be removing more than the top centimeter (1/2 inch ) of the jointing sand. Remove as little sand as possible between the pavers when the cleaning takes place. Hold the lance at a distance of no less than 200mm (8 inch) from the block paving surface. If possible when pressure washing block paving use the lance at an angle of 45 degrees to the paving surface.

When you are pressure washing block paving never aim the jet of water directly at or into the paving joints from overhead. This can do severe damage to the underlying grit sand base the block paving is laid upon.


Frequently asked questions about pressure washing block paving.

When is the best time to clean block paving with a pressure washer?

You can clean your block paving at any time of year with a pressure washer. Our recommended times of year would be autumn and spring. This is because its always good to have clean block paving before winter sets in to avoid slippy paving and spring cleaning is great before things begin to grow. After cleaning with a pressure washer consider applying an apply and leave cleaner. These help keep your block paving weed, algae and moss free for longer. Which cuts down on the need to use a pressure washer to clean your block paving.

Can you clean block paving with a sealer applied to the surface?

Yes. If your block paving has been sealed with a sealant you should be perfectly fine to clean block paving with a jet washer. If a sealer has been applied by sprayer or roller & tray, you should only have to wash the paving using the jet washer to rinse the paving rather than to blast the surface. Always check with the sealer manufacturer if you are unsure. You may need to re-apply any paving sealer after pressure washing block paving. Especially if an acrylic sealer has been used to seal the paving.

Will  pressure washing my block paving cause white staining on the surface?

The white blooming or staining on the surface of block paving is caused by salts being released by the paving. This is often referred to as efflorescence. If your paving is newly laid, cleaning with a pressure washer could release salts from within the pavers so this could be possible. Salts will often be released way before its time to clean new block paving with a power washer. If your paving is old or has been laid for some considerable time then cleaning with a pressure washer will not cause white staining or efflorescence to develop.


 Do you want to buy a new pressure washer to clean your block paving? Do you want more information to help you decide the best pressure washer you can buy to clean your paving. Read our pressure washer reviews.

13 comments

  1. Thanks for sharing this. I have exactly this kind of block paving at home. How often can this be done in your opinion?

    1. Hello Veronique,
      You can pressure wash your paving as often as you like but the downside is that if not done correctly, the block paving will become weak over time. If you follow the guide and do not wash/blast all the deep kiln dried sand away and the kiln dried sand is replaced after each wash then you should be fine. If you do plan on washing your paving quite often the block paving would definitely benefit from having a polyurethane or high resin acrylic sealer applied to the surface to retain the sand and stop ingress of water into the paving joints.
      Or you could apply a good quality ‘apply and leave cleaner‘ to the surface then hopefully the block paving doesn’t need as much cleaning and when it does it won’t need as much use with the jet washer.
      Thanks and I hope this answers your question Veronique.

      1. Hi John,

        Thanks a lot for your answer. I don’t think I could apply the joint sealer because the surface is so big it would take me like 3 months to do all the joints. 😉 I think the cleaner would be a great idea to start with. It has never been done so it’s a big mess with weeds everywhere. Thanks again for your help.

    1. Hello Phil,
      Yes using polymeric sand is fine but the downside is that the sand is not as free flowing as kiln dried sand and may not sink to the bottom of the paving joints to give the strength needed between the pavers. If the pavers have joint sand halfway up the paving joints and then you use a polymeric joint sand then this will be an excellent way of stoping weeds, stoping the loss of sand and give a great long term strength to your paving. Making the sand set hard. Rather like sealing the sand with a sealer.
      If you are unsure what polymeric sand is, the joint sand usually contains a chemical to bind the particles of sand together once the sand is spread into the paving joints. This is activated either by water or atmospheric air.

  2. When cleaning with a pressure washer it is crucial to make sure you understand that you can damage a lot of your belongings very easily if not careful. I learnt this from experience. This write up is great for new guys in learning about damage that can be done when pressure washing. Thank you for taking the time out to write this.

  3. My neighbours had their drive jetwashed last year and left dirt and grit all over our drive, under our back gate and all splashed up our side door an an ingress of water under my garage door. What can be done to prevent this from happening again? It was extremely annoying and very thoughtless of them I thought.

    1. Hello Jen, Yes it was very inconsiderate of the contractor to not consider you as the neighbours. The contractor should have washed down any mess they made such as your door and gate or been more cautious with the way they operate. They were proberbly very inexperienced or just unprofessional in the way they carry out their cleaning.
      Have you made them and your neighbours aware of the mess they have left?
      For future reference i would recommend using cloth rags of bin bags to block the gap under a garage door. If you do find dirt and grit splashes try to remove them by rinsing with clean water asap.
      Hope this helps Jen.

  4. Awesome read thanks alot. I’ve seen it happen too many times on DIY projects where people blast the block paving and end up destroying the alignment. I like to use a mild detergent when I do paver cleaning. Have a good day.

  5. Nice post. ‘Tiger stripes’ I like it. The amount of companies out there that don’t even bother resanding is phenomenal. And I definitely agree with the use of weed killer first and the use of chemicals where appropriate.

    1. Thanks Paul, I agree. It’s usually because the cleaning companies have to return to the job to replace the lost sand when the paving is dry. This means visiting the job twice. Most can’t be bothered or don’t factor the cost of returning to the job to re-sand the paving oonce dry into the quote for cleaning the paving in the first place. But i’m glad your company understands the importance of replacing the lost sand in the paving joints. Good work. PS. Nice company name by the way LOL.

  6. Hello,
    I very recently had a patio sealed but the contractor did not pressure clean it prior to sealing and the once dirty patio is now a sealed dirty patio! Can I pressure wash it to remove the discoloration and ingrained muck? If i do will it remove the seal? I don’t know what seal he used but it smelt strongly for days so I am guessing it was not acrylic.
    Thanks for your advice.
    Kind Regards,
    Peter

    1. Hello Peter,
      Thanks for your inquiry,
      This is a common question we often get asked at Paving.org. What to do if paving gets sealed without first cleaning the paving which then seals in the dirt!
      In response to your question :
      If the smell lingered for days then they probably used a solvent based sealer. You can buy both solvent based acrylic and polyurethane sealers. If they have done a poor job then they more than likely used the cheaper acrylic solvent based block paving sealer rather than the more expensive polyurethane sealant. Are you able to ask them what type they used? Or complain that they never removed the dirt before applying the sealer?
      You would need to use a solvent to remove a solvent based sealer because it will need to dissolve the resins. You could try using the pressure washer and maybe it may work in some areas as the dirt may have provided a barrier between the paving and the sealer. But more often than not there will still be traces of sealer that has been absorbed by the paving.
      My recommendation would be to test a small area first with the pressure washer or a resin sealer remover to see if it works before attempting the whole driveway. Or get in touch with a local paving sealing contractor to ask for their advice. They should be able to advise you what you can do.
      Good luck and keep me updated how you resolved the issue.
      Thanks
      John

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