Jet Wash vs Soft Wash on Block Paving

How block paving is built

Concrete or clay blocks sit on a bed of sand, with fine jointing sand brushed between them. That sand locks the blocks together so they do not shift under car tyres. Lose the sand, and blocks can start to rock, sink or spread at the edges.

That is the main reason washing method matters so much on block paving compared with a single slab of concrete.

What jet washing does well

A jet wash removes surface dirt, moss and algae quickly, and on sound blocks with sand-filled joints it can be used safely at a controlled pressure and angle. It is good at lifting embedded grime from textured blocks.

Problems start when pressure is too high, the lance is held too close or the jet is aimed straight down into the joints.

What soft washing does well

Soft washing uses a cleaning solution at low pressure and lets it work on algae and organic staining, followed by a gentle rinse. It leaves jointing sand largely in place and is kinder to older or softer blocks.

It is less effective on thick moss in joints, which still needs physical removal, and results on algae can take some days to show fully.

Why a combined approach often wins

In practice, many block drives are best treated in stages: weeds and moss lifted from joints, a controlled wash to remove surface dirt, a treatment where suitable to deal with algae, and then re-sanding of the joints. Each stage does what it is good at.

We choose the mix on the day based on the drive's condition. The method is explained in the quote.

Re-sanding after cleaning

Any wash removes some joint sand, and old joints are often already low. Brushing in fresh kiln-dried sand afterwards restores the lock between blocks and leaves less room for weeds. See our block paving re-sanding guide for detail.

Skipping this step is the most common reason a freshly washed drive goes green again within months.

Questions to ask any cleaner

Ask how they will deal with weeds in joints, what pressure and technique they use, whether they re-sand, and what happens to the dirty water. A clear answer is a good sign.

Our soft washing vs pressure washing guide covers the same debate for roofs and other surfaces.

Clay pavers versus concrete blocks

Concrete blocks are the most common type, but older and higher-end drives may use clay pavers. Clay is dense and often holds its colour well, while concrete blocks can wear to expose aggregate. Both benefit from controlled cleaning, but clay pavers can be more forgiving of washing and less forgiving of strong chemicals.

If you know which you have, mention it. If not, a close-up photograph usually tells us.

Dealing with run-off and splash

Washing block paving produces dirty water and loosened sand. We think about where it goes before starting: drains, flower beds, the road and neighbouring property. Splash onto walls, doors and cars is rinsed off as the work progresses.

Silt washed into a road gully can block it, so we avoid sending heavy debris that way.

Expectations after the first rain

Freshly cleaned block paving can look slightly patchy until it has dried fully and had its first rain. Re-sanded joints settle over a few days. Some owners like to top up joints again after a couple of weeks.

Algae that was treated may continue to fade over the following days.

Getting a block paving quote

Our dedicated block paving cleaning page explains the service in detail, and driveway cleaning covers other surfaces too. Send photos for a free quote.