Why Driveway and Paving Cleaning Is the Foundation of the Trade

For most pressure washing businesses, driveway and block paving cleaning is where the volume comes from. It is visible, high-impact work — the before and after is obvious to the client and to every neighbour who walks past. Done well, a single driveway clean generates referrals, repeat bookings, and the kind of word-of-mouth that no amount of advertising can replicate.

Done poorly, it generates complaints. Tramlines across the paving. Sand washed out of the joints. Water pooling against the house. A surface that looks patchy because the operator rushed the edge work. These are avoidable outcomes — every one of them — and this module covers how to avoid them.

Site Assessment — Before You Set Up

Every job starts before the machine comes out of the van. Walk the surface with the client — or alone if they are not present — and work through the following assessment before you connect a hose.

Surface type and condition

Is it block paving, imprinted concrete, natural stone, plain concrete, or tarmac? Each has a different pressure tolerance and a different risk profile. Module 6 covers substrate identification in detail — by this point you should be able to identify what you are dealing with and what that means for your method selection.

Pre-existing damage

Cracked or sunken blocks, loose pointing, spalled concrete, previous sealant that is peeling — photograph all of it before you start. If a client claims damage after the job, your pre-clean photographs are your primary defence. This is not optional.

Staining that may not lift

Old oil staining that has penetrated the surface, rust marks from metal furniture or drain covers, tannin staining from leaves — point these out to the client before you start. Manage the expectation now, not after you have cleaned around it and they are standing there wondering why it is still there.

Drainage

Where will the water go? Is there a drain on the driveway? Will runoff travel onto the road, into a neighbour's garden, or towards the house? Plan your working direction and runoff management before you start. This is covered in detail in Module 12.

Access and obstacles

Parked cars, wheelie bins, garden furniture, plant pots — these need to be moved before you start, not worked around. Agree with the client what needs to move and who is moving it.

Equipment Set-Up

For a standard driveway or paving clean you will need:

• Pressure washer (cold water machine adequate for most domestic work)
• Rotary surface cleaner — sized appropriately for your machine's flow rate
• Trigger lance with 25° nozzle for edge work
• Hose — long enough to reach the furthest point of the surface without dragging across wet areas
• Pre-treatment chemical — algaecide/biocide and/or degreaser depending on contamination type
• Pump sprayer or downstream injector for pre-treatment application
• Kiln-dried jointing sand if re-sanding is within your scope
• Stiff brush for sand application
• Camera or phone for before/after documentation

Pre-Treatment — When, Why, and How

When pre-treatment is needed

For surfaces with significant biological growth — green algae, black algae, moss, or lichen — pre-treatment with a biocide or algaecide before pressure washing dramatically improves the result and reduces the effort required. The chemical kills or weakens the growth at a cellular level; the pressure washing then removes it cleanly rather than just displacing it.

For oil or grease contamination, a degreaser pre-treatment applied and allowed to dwell breaks down the hydrocarbon bonds before water is applied. Trying to remove fresh or heavy oil contamination with pressure alone rarely produces a satisfactory result.

When pre-treatment is not needed

Lightly soiled surfaces — atmospheric dirt, light mud, surface dust — generally do not require pre-treatment. Over-applying chemicals where they are not needed adds cost, extends the job, and creates unnecessary runoff.

How to apply pre-treatment

Apply by pump sprayer or downstream injector, working from the furthest point back towards your exit. Ensure even coverage across the whole surface. Allow the correct dwell time — typically 5–15 minutes for a biocide, less for a fast-acting degreaser — without letting the chemical dry out. On hot days, work in smaller sections or pre-wet the surface first.

Surface Cleaner Technique — Getting a Consistent Result

The rotary surface cleaner is the right tool for flat horizontal surfaces. It produces an even, circular cleaning pattern from two counter-rotating nozzles, eliminates the fan-stripe tramlines that a lance produces on large flat areas, and significantly reduces the time taken compared to lance-only cleaning.

Working pattern

Start at the point furthest from your water source and work back towards it in overlapping parallel passes. Each pass should overlap the previous one by approximately 20–30% to avoid visible lines between passes. Work at a steady, consistent walking pace — too fast and the surface is under-cleaned, too slow and you risk etching softer surfaces.

Height and pressure

Keep the surface cleaner flat on the surface and moving constantly. Lifting it — even briefly — produces visible marks. Pausing it in one spot produces a circular clean patch that is very difficult to blend out afterwards. Keep it moving.

Avoiding tramlines

Tramlines on block paving are caused by lance technique on large areas, or by a surface cleaner that is too small, moving too fast, or not overlapping passes correctly. If you see lines appearing, slow down and increase your overlap. Do not try to correct tramlines by going back over them with the lance — this usually makes them more visible.

Edge Work — Lance Technique for Borders and Wall Bases

The surface cleaner cannot reach within approximately 50–75mm of walls, steps, and borders. This area must be cleaned with the lance — and it is where most operators produce their worst work, because they rush it at the end of the job.

Nozzle selection for edges

Use a 25° nozzle for edge work. A 15° nozzle produces too concentrated a stream and risks etching or lifting pointing. A 40° nozzle does not deliver enough impact to clean effectively at the reduced standoff distance you are working at along a wall base.

Technique

Hold the lance at a low angle — approximately 30–45° to the surface — and work along the wall base in smooth, consistent strokes. Keep the nozzle 150–200mm from the surface. Work away from the wall so that disturbed contamination and water travel away from the structure, not up against it. Overlap each stroke.

Steps and raised edges

Clean the riser (the vertical face) first, then the tread (the horizontal surface). Water and contamination travel downwards — if you clean the tread first, the riser will contaminate it when you clean it next.

Efflorescence and Salt Deposits

Efflorescence is the white, powdery or crystalline deposit that appears on the surface of block paving, concrete, and natural stone. It is caused by soluble salts within the substrate migrating to the surface as water evaporates. It is extremely common on new block paving and on older paving that has been subject to significant moisture movement.

Will pressure washing remove it?

Pressure washing alone will reduce the appearance of efflorescence temporarily, but will not remove it permanently. Water accelerates the migration of salts — which is why heavy pressure washing can actually make efflorescence worse on susceptible surfaces in the short term.

Correct treatment

For significant efflorescence, an acidic efflorescence remover applied after the main clean and allowed to dwell will dissolve the salt deposits. Rinse thoroughly — acid residue left on the surface will continue to react. Always test on an inconspicuous area first, particularly on natural stone which can be etched by acidic treatments.

Post-Clean Rinse and Runoff Control

Once the main clean is complete, rinse the entire surface thoroughly with clean water, working from the highest point to the lowest, directing water towards the drain or the intended exit point. This removes chemical residue, dislodged contamination, and kiln-dried sand debris from the cleaning process.

Check that no significant volume of contaminated water has pooled against the house, against a boundary wall, or near a drain that discharges to surface water. If it has, address it before you pack up — do not leave it for the client to discover.

Re-Sanding Block Paving

Pressure washing removes jointing sand from block paving. This is unavoidable — the water gets into the joints and displaces the sand. On a well-executed clean, the loss is moderate. On an over-pressured clean with a lance rather than a surface cleaner, the loss can be significant.

Is re-sanding within your scope?

This is a commercial decision you need to make before you quote. Some operators include re-sanding as standard. Others offer it as an add-on. Others do not offer it at all and advise the client to arrange it separately. Be clear in your quote which applies — a client who expected their sand to be replaced and finds it was not will not rebook or refer you.

How to re-sand correctly

The surface must be completely dry before kiln-dried sand is applied — wet sand will not settle into the joints correctly. Broadcast the sand across the surface, then work it into the joints using a stiff brush or a plate compactor with a rubber pad. Brush off the excess. On a very hot day, even a surface that appears dry may retain moisture in the joints — if in doubt, wait.

Client Handover

The handover is the last impression you leave. Do it properly.

Photographing and Documenting the Job

Before you leave, take your after photographs. Match them to the before photographs you took on arrival — same angles, same areas. If you photographed pre-existing damage before the clean, photograph those same areas again after the clean to confirm the condition is unchanged.

Store your before and after photographs against the job record. At minimum, record the client name, address, date, what was cleaned, what chemicals were used, and any pre-existing conditions you noted. This takes five minutes and has saved operators from five-figure claims.