How to clean block paving with a pressure washer.
Pressure washing block paving should be used to gently clean and rinse the paving rather than used to blast the paving clean. Why?
In the long-term, pressure washing block paving with a pressure washer will lead to your paving becoming weak because of the loss of the deep jointing sand. This is especially true if you use a pressure washer to constantly remove any weeds and moss from the paving joints. Why? Because using a pressure washer for removing deep ingrained dirt or weeds will also remove the deep paving joint sand.
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.
Why show caution when using a pressure washer?
The 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 at close range which is needed to remove weeds and moss. “But I will replace it” I hear you say.
Well if you remember when you’re paving was laid, the contractor would have used a whacker plate compactor to not only compact the paving but to also force the kiln dried sand into the joints of the paving, locking 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.
Power washing block paving is not normally needed if it is regularly maintained. But sometimes if your block paving does need cleaning and the dirt and grime is heavy, jet washing your paving does make cleaning of the paved area easier and quicker than having to scrub the paving with a brush. Especially if there is a large area of driveway or patio be cleaned or the dirt and grime is very heavy on the paving surface or the moss is extensive.
This is why we would recommend using a ‘apply and leave’ paving cleaner. They clean your paving over the long-term, natural. keeping your paving clean. Pressure washing your block paving is not needed then. You will be amazed at how well these cleaners work. You do not see instant results but your moss and dirt will start to be eliminated after a couple of days. Then every time it rains your paving becomes a little cleaner. The cleaners keep on working for up to 6-12 months afer application. Well worth a try in our opinion. But please be patient once applied. It does take a few days to a few weeks to see real visible results.
Before you begin pressure washing block paving
Always begin by giving your block paving a good sweep with 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 and 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 first or any sunken area of paving that may need to be relaid first.
Does any of the block paving need to be relaid? 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.
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 between the pavers when the cleaning takes place and held 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.
Apply weed killer to your paving before you use your pressure washer
If you have applied a weed killer, allow the weeds, moss or algae to die before starting to clean your block paving. After you have applied a weed killer to the 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.
Can you clean block paving with a sealer applied to the surface?
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, 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 sealer after pressure washing block paving, especially if an acrylic sealer has been used to seal the paving.
Step-by-step on how to clean block paving with a pressure washer.
- Apply a relevant cleaner if needed following manufactures instructions
- Begin by pressure washing your block paving by starting in a corner above the run off area of the dirty water so that you don’t have dirty water running on to your cleaned area of paving.
- Always try to power wash the driveway or patio away from and not towards buildings, cars and neighbours property unless unavoidable.
- 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 the house walls and windows afterwards.
- 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 for cleaning.
- 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 if that’s where your dirt ended up.
- Once the block paving is clean you need to allow to dry before re-sanding 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.
- After pressure washing block paving and then replacing the jointing sand, finish by re pointing with cement any areas of pointing that may have come loose with the use of the power washing.
You’re done! You’re now an expert in pressure washing block paving.