How to clean a driveway or patio

Driveways and paths are among the first things visitors see, and they often collect green and black growth. A driveway also has to cope with vehicles, parking and heavy use, so cleaning it involves more than removing algae. This guide covers growth on paving, moss in the joints, dark deposits and oil stains.

What grows on driveways and paths?

What accumulates on a driveway is rarely just one thing. It's typically a mix of biological growth and stains from daily use, and once you know the difference, you'll also know which method to use.

• Algae form a thin green or black film on the surface. They make paving slippery and grow quickly in damp, shaded areas.
• Moss forms small green cushions in joints and along edges. It retains water between paving blocks and can spread if left undisturbed.
• Black deposits are the dark, almost sooty film that many mistake for dirt. It's usually black algae and biofilm that adheres to the surface and cannot simply be swept away.
• Oil stains and tyre marks are common on driveways. Oil, petrol and tyre rubber can leave dark marks in porous paving that ordinary cleaning does not remove.

Living growth and oil stains need different treatments, so cleaning a driveway often involves two separate tasks. For more on green algae, see our guide to green algae on patios.

Different surfaces require different methods

A driveway can be made of many materials, and they don't all tolerate the same treatment. The most important thing before you start is to know what you have underfoot, so you don't damage the surface in an attempt to clean it.

• Concrete paving are robust, but the surface can be smooth or porous. Moderate pressure is enough; too much pressure makes the surface rough, allowing algae to settle more easily again.
• Cobblestones and setts have many joints where moss and weeds love to grow. The stone itself can withstand a lot, but the joints are vulnerable, as strong pressure washes out the jointing material, leaving loose stones.
• Concrete blocks and interlocking pavers are common driveway materials laid closely together. They can withstand thorough cleaning, but jointing sand needs topping up afterwards to keep the blocks stable.
• Slate and other natural stone need a method suited to the material. Some stone is sensitive to pressure and cleaning chemicals, so gentle treatment is usually the best starting point.

The principle is always the same: the softer and more porous a stone is, the more gently it should be treated. If you're unsure what your driveway can withstand, it's worth getting a professional opinion first.

Moss and weeds in the joints

The joints are the driveway's weakest point. This is where moss and weeds take hold because moisture, soil, and seeds collect between the stones, and once something has grown, it retains water even better.

To remove moss without weakening the joints, avoid washing out the jointing material. Boiling water can kill some moss in small areas without cleaning chemicals. A paving scraper or stiff joint brush can remove it physically with care.

A suitable algae treatment applied at low pressure can provide a longer-lasting result without washing out the jointing sand. After cleaning, top up any missing sand to keep the paving stable.

Oil stains and tyre marks on driveways

Oil stains are what differentiate driveways from all other paved surfaces. They are rare on patios but almost unavoidable on driveways, and they behave entirely differently from algae. The oil has penetrated the porous stone, so it cannot simply be brushed or rinsed away.

Fresh oil can be absorbed with cat litter or oil-absorbing granules, left for 24 hours before sweeping them away. Older stains need a degreaser, sometimes applied more than once. An ordinary algae remover does not remove oil.

Very old stains rarely disappear completely, but a suitable degreaser and hot-water pressure cleaning can lighten them considerably. Professional products and equipment are particularly useful for treating oil within porous paving.

How we clean driveways and paths

We assess the material and the type of dirt before choosing the pressure or product. Smooth concrete slabs, cobblestones with deep joints and delicate natural stone each need a different approach. We then plan the cleaning and any separate oil-stain treatment.

The work usually has two stages: careful cleaning to remove algae, dark deposits and moss, followed by an algae treatment to slow regrowth. Oil stains are degreased separately, and missing jointing sand is topped up afterwards. We use the same basic approach for professional paving cleaning and algae treatment, adapted for the vehicle use and oil exposure of a driveway.

Professional cleaning matches the pressure and product to your paving, protecting the surface and joints. You receive a fixed price before we start, and we respond within 24 hours. For more about costs, see our guide to paving cleaning prices and methods.

Keeping the driveway clean afterwards

Regular care helps prevent growth and deal with stains before they become established.

• Ensure water can drain away. If water stands on the surface after rain, algae will quickly grow. Check for proper drainage.
• Keep joints free of soil and seeds. Sweep regularly to prevent material from accumulating where moss and weeds can take root.
• Address oil stains immediately. The faster you absorb a fresh stain, the less it will penetrate.
• Allow more light and airflow. More sun and air mean the paving dries faster, making it harder for algae and moss to take hold.
• Consider sealing. Sealing reduces water and oil absorption and can extend the time between cleans.

If green or black growth returns every year despite regular care, professional assessment and treatment may help.

Clean it yourself or hire a professional?

A short path or small driveway area can be maintained with a brush, soap and patience. Professional help makes sense for large areas, stubborn oil stains, delicate natural stone or recurring growth.

For professional cleaning of paving and driveways, send photographs and the approximate area for a fixed quotation, with a reply within 24 hours, or call 20 98 88 11. Cleaning eligible paving may qualify for the household services deduction if the Danish Tax Agency's conditions are met; the deduction applies to qualifying labour, not the whole bill. Read our guide to black deposits and lichen on paving.

Frequently asked questions

How do you remove moss between paving blocks?

Avoid washing out the joints. For small areas, a paving scraper, stiff brush or boiling water can help remove moss. Larger areas may benefit from a suitable algae treatment applied at low pressure. Top up any missing jointing sand afterwards.

Can oil stains be removed from the driveway?

Fresh oil can often be absorbed with cat litter or oil-absorbing granules left for 24 hours. Older stains need a degreaser and may require repeated treatment. Very old marks rarely disappear completely but can be lightened with suitable degreasing and hot-water pressure cleaning. Algae remover does not treat oil.

Can concrete paving be pressure-washed?

Concrete blocks and interlocking paving generally tolerate cleaning at moderate pressure. Keep a consistent nozzle distance and avoid excessive pressure, which roughens the surface and washes out jointing sand. Top up missing sand afterwards. Delicate natural stone needs a gentler, suitable method.

How often should a driveway be cleaned?

It depends on shade, moisture and use. A driveway that is swept regularly and drains well may need a thorough clean only every few years. Damp, shaded areas need checking more often. Sealing after cleaning can extend the interval.

How much does it cost to have a driveway cleaned?

The price depends on the area, paving material, amount of growth or oil staining, and any follow-up algae treatment. We provide a fixed price before starting. Request a no-obligation quote, and we will assess your driveway and respond within 24 hours.