It's not uncommon to have a beautiful pedestrian pathway to facilitate access and circulation or a paved terrace to enjoy outdoor spaces. Over the years, the sand or mortar joints in these pavements can become dirty and colonised by weeds or moss. How to maintain joints using eco-friendly methods? Are there special tools or miracle recipes to restore joints to their original condition?

We'll tell you everything in our tutorial!

Why clean terrace or pathway joints?

Outdoor terrace and pathway installations require some maintenance once the block paving is laid with sand or mortar joints. Over time, joints can become filled with mould, fungi, lichens, moss, leaf debris or weeds. Quite quickly, you'll need to clean the joints, preferably using alternatives to chemical products. How to clean outdoor paving, particularly the joint surfaces?

What tools to use for alternative weeding?

Block paving cleaning should be done regularly. When joints are soiled and unwantedly vegetated by weeds, use effective equipment to restore their shine such as:

  • The scraper: this triangular-headed tool, well sharpened, allows you to scrape between paving blocks to remove weeds or lichens growing there or any deposited residues. Whether for tile or pavement joints, the weeding results with a scraper are quickly visible. Some elbow grease is needed if the terrace or pathway surface is large.

  • The weeding knife: with its small pointed and well-sharpened blade, the manual weeding knife or weeding knife allows you to scrape joints between paving blocks or slabs that make up a pathway or cover a terrace. Thus, moss and other weeds are quickly eliminated in sometimes inaccessible places. The joints are quickly weeded and cleaned.

  • The stiff broom: very similar to an indoor broom, only the steel or nylon bristles differ. Regular sweeping over block paving on a terrace, patio or pathway is enough to restore their shine and make them look new again. Stubborn weeds will come loose with just a sweep of the broom.
  • The thermal weeder: here's an effective tool for cleaning terrace or pathway joints invaded by moss or grass. Electric or gas-powered, the heat source burns plant cells without damaging the block paving surface. Weeds take 2 to 3 days to completely dry out. Depending on the surface to be cleaned, research well before purchasing.
  • The weeding brush: this brush, whose diameter varies depending on models and strimmer brands, is made of twisted steel wire or nylon. It's only used on irregular or old paving. In one pass, it scrubs away moss, weeds and other outdoor debris. Guaranteed quick cleaning of large surfaces! Don't forget to wear gloves, safety shoes and protective goggles. Before purchasing this tool, check whether it can be used on your particular surface.
  • And the pressure washer: the temptation to use a pressure washer is strong but be careful as the pressure may damage natural joints by not just removing stains but the joints themselves. Pressure washers are recommended for cleaning installations with mortar or more resistant epoxy resin joints. Be careful as frequent use can deteriorate the waterproof layer of reconstituted stone surfaces, create micro-cracks or make tiles porous. This cleaning should be occasional. Try gentle methods first!

What product to use for cleaning paving joints?

Whether cleaning old paving, concrete blocks, natural stone slabs or others, how to clean joints while prioritising natural, environmentally friendly and effective methods using products like:

  • Black soap: natural, a simple mixture of black soap (the same used against aphids), 2 tablespoons with 10 litres of warm water (read precautions on bottles) is enough to clean slightly dirty mortar joints. Scrub with a stiff broom, leave for 15 to 20 minutes then rinse thoroughly with clean water. Stains and other moss will disappear to restore impeccable joints.
  • White vinegar: to maintain joints soiled with mould or lichen, make your own treatment product instead of using industrial abrasive detergents. Mix lemon juice, ½ glass of white vinegar in 1 litre of water. White vinegar has the advantage of limiting mould appearance. Stir and apply to joints then scrub with a stiff-bristled broom. You'll restore sparkling terrace or pathway joints!
  • Bicarbonate of soda: mix the equivalent of 4 tablespoons of bicarbonate with 10 cl of warm water, directly in a spray bottle. Spray the joints and leave the mixture to work for 2 hours. Then scrub the joints with a stiff-bristled broom and rinse.
  • Sodium percarbonate: especially effective for removing mould stains, percarbonate will whiten joints so be careful about the original colour to restore. Dilute one measure of product in 9 measures of water (cap, spoon, cup, etc.). Apply directly to joints and leave for about 2 hours. Vigorously brush the joints then rinse with clean water to restore shine to mouldy joints.
  • Cooking water: here's the 100% natural weeding method for a terrace or pathway with natural planted joints. Use still-hot vegetable or starch cooking water on weeds between paving blocks and slabs. The thermal shock will burst plant cells, foliage will blacken and plants will eventually die. Don't hesitate to repeat the operation several times if needed.

Paving before cleaning (photo S.Chaillot)

Did you know? For minimal maintenance, you can joint paving blocks or slabs completely naturally with ground cover plants that will act as joints like wild thyme (Thymus serpyllum), mondo grass (Ophiopogon japonicus), Irish moss (Sagina subulata) or Corsican mint (Mentha requienii).