How to clean your patio so it’s perfect for outdoor living

With the sun in a longer arc through April’s broken cloud and warming those back slabs, it’s time.

This patio is probably green and quite dull, with small invasive plants with microscopic botanical growth, including algae, blackheads and other lichens and more visible still – moss and tiny stubborn weeds rippling from every crack. and moist, mineral-rich crevice.

Lichen looks quite pretty, it’s a fascinating part of natural history – but it can wash out color from tinted conglomerates if left too long and then torn off.

Algae and moss can both prove slippery and ruin the elegance and sophistication of an urban paving choice.

Clearing stones, concrete driveways and any variety of hard pavement is a deeply satisfying, muscle-boosting and calorie-burning afternoon of work.

Grab waterproof pants, shoes with good grip, sturdy gloves and let’s go.

First, clean the patio and any paving as thoroughly as possible. Furniture, containers, anything that could be airborne by a pressure washer or hide creeping greenery from your work.

Before we get started, let’s look at the clues – where’s the glistening slime and uncontrolled growth the worst? We must always be very aware of drainage problems to avoid the accumulation of rainwater on impermeable surfaces around the house.

The very slight slope of the patio should direct water away from the walls of the house. You can introduce flexible planted joints where water can flow and/or include dedicated drainage as part of your rainwater system.

A patio knife or weeding finger requires no chemistry, just lots of patience for a clean, weed-free finish between paving and soft joint blocks. Expect to pay between €7 and €15 for one, depending on the brand.

A patio should be at least 150mm below the DPC (Damp Proof Course) of your home and back away from the walls or fence by approximately 25mm in 1.5m.

If you find your paving is green and wet near the house, watch where the rain is flowing and consider straightening the slope or introducing drain grates to safely direct it away. Before exiting, the hose and brushes start on soft grout lines with an L-shaped paver knife to remove the weeds, placing them in a bucket. This is also a good time to edge the lawn meeting the patio.


If you have rustic concrete or real stone paving, especially if you have left it unsealed for character, we seek to control rather than eradicate any growth. With soft sandy joints, you can pull off the shaggiest of your uninvited visitors, but facing flagstones and walkways, uncontrollable lichens and algae could offer a free fall of charm.

Regular scrubbing with a wire paving brush and a bucket of warm water with a little dish soap will eliminate many problems with a little attrition – no heavy chemical control required. For a safe detergent solution, try a cup of dishwashing liquid or baking soda and salt dissolved in a 10-quart bucket of warm water.

Try spraying small weeds with almost white vinegar if you can’t remove them.

Failing that, a good cup of vinegar in a bucket of water can clean and brighten most stones, concrete and pavers (1:1 ratios are excessive in my opinion and any acid is destructive to concrete if it is left on the surface).

Throw the buckets on your paving, scrub it well and work it towards the drain with your stiff bristle brush. Try to keep control of this crazy work all year round.

Rinse with clean water, avoiding your flowerbeds.

Guide the waste from the stones with the hose or fan jet of your pressure washer, as if settling into your grout or grikes, they will provide nutritious litter for small and large spore and seeding invaders.

Repair any voids you leave in soft joints with horticultural sand pinched with a little joint stabilizer. Keep a bucket there and put it away as you go. For elbow grease to be most effective, deploy this method four to five times a year, not just every spring.


Pressure washers are a brilliant all-around outdoor kit for all but evaporating dirt and grime, but in the wrong hands they can prove an unexpected and destructive weapon.

Deployed on everything from crumbling mortar to greenhouses and patients, pet ponies, the force of liters per second dropped from a pressure washer can blast joints in walls and cobblestones, throw you backwards from a ladder, lifting the flakes of a more delicate patio. rocks and small rocks ricochet off the windows and paint of your husband’s car.

Familiarize yourself with the machine before you start – the spray patterns, force setting, etc. (see our guide to buying the right pressure washer). You can combine working with a scrub brush and rinsing with the pressure washer – whatever you do, start by removing the biggest debris from the deck with a good sweep.

Once the machine starts, work through the joints, not inside, as you can remove sand or even dislodge mortar.

One of the irritations of using a pressure washer is the muddy spray that will fly up and over everything else, so allow time to rinse the entire area, working down and towards the drain.

Dedicated patio heads, offered with Karcher machines, avoid this inconvenience. Its one-litre bottle Stone & Patio Cleaner is fully biodegradable, provides stone wind and weather protection, and can be used in its plug-and-clean system. Prices from around €9.99 at most good DIY stores.

Angle your washer wand at 30C-45C to soften its impact and move in a side-sweeping motion, rather than piercing with intense force.

If using an additive, use as little as possible to get a good clean, let it sit on the tiles before the final rinse, and direct puddling down the drain with fresh water only if the additive is biodegradable and suitable for pouring down the drain in high solution.


If you don’t feel like pressure washing or scrubbing the area, you’ll venture into the chemical solutions. Path and patio cleaners are relatively tough in chemical terms, containing a solution of benzalkonium chloride or a mild acid wash – a popular choice would be something like Britons Patio Magic, £13.65, from B&Q. Jeyes Outdoor Cleaner (it says it will kill 99.9% of bacteria and viruses, including the Sars-Cov2 coronavirus if you lick your cobblestones) is a classic favorite for the job; €5 per litre.

Use as little as possible and wear rubber overalls, goggles and gloves to spare your skin and eyes.

This product and many others are particularly lethal to pond fish.

Chemical cleaners are applied using a watering can, a low-pressure sprayer (often built-in tools offered by the manufacturer) on paths and even on moldy walls.

It is then left to show results over a number of days. Remember that anything you use with any toxicity will seep into your groundwater and may splash nearby vulnerable beds and containers.

Read the instructions and follow them exactly, keeping children and pets out of the area until it is safe and dry. Most stones, cobblestones and all aggregates are porous to some degree. Sealing their surface, especially patterned concrete with an appropriate product, will keep them looking fresher for longer and reduce that hard work and water work.

Bleach is not suitable for artificial concrete, so if you must use it and risk your plants and edging grass, use as little as possible, heavily diluted on natural pavers only, followed by a very good rinsing by soaking.

Look for commercial yet eco-friendly patio cleaner brands, including Algon, which work just like the chemical division – throw it in and forget it; €14.50 for 2.5l.