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30th November 2018

Sandstone is one of the most popular landscaping products around, and it’s easy to see why. Its warm colours, versatility and eye-catching finish make it a great choice for garden paving. But like all paving, it’s exposed to the elements of the Great British weather, so regular maintenance is essential to keep your sandstone looking its best.

Sandstone – Basic TLC required

No matter where you live, all patios and other paved areas need some basic maintenance to keep them looking their best. It doesn’t matter how much you spend on top quality materials, nor how well the paving is laid. All paving, from the top-of-the-range downward, needs some TLC.

Despite what the slick sales brochures will tell you, there’s really no such thing as truly “maintenance-free” paving. Just like anything else, basic maintenance is required in order to keep paving in prime condition, while a lack of maintenance will allow paving to deteriorate over time.

Give your patio a new lease of life

Even if it’s just a basic wash-down with soapy water, all types of paving will look so much better for occasional cleaning. And certain types of paving tend to need a bit more care and attention to ensure they always look as smart as possible. Sandstone paving (often called Indian Sandstone) is one of these.

The good news is that cleaning is generally simple, and you can give even the most neglected or abused patio or paved area a new lease of life with minimal effort.

With sandstone paving, discolouration and a loss of the sheen and texture of paving slabs can be a problem. The passage of time, not to mention traffic, as well as the type of plants that surround the paving slabs, and the proximity of the slabs to water all have an impact on how fast the paving slabs become dirty and how frequently the paving slabs need to be cleaned.

The materials that you need to clean sandstone paving slabs depend on what’s causing the discolouration and how porous the sandstone is. Sandstone is generally quite porous (i.e. it absorbs water), and very porous stone needs particularly careful attention to prevent the removal (erosion) of the stone when it’s cleaned.

What causes stains on sandstone?

Knowing what has caused the discolouration of your paving stones is a great help in determining what cleaner to use and what cleaning method to use. The most common contaminants are:

  • Dirt: dirt gets trampled into the stone surface. Dirt is also attracted to sandstone because of its negative electrical charge (yes, really!).

  • Algae: any green discoloration of sandstone is usually caused by algae. Algae are plants or plant-like organisms that exist in the air. The spores are microscopic but they can travel miles on the wind. The algae spores then take up residence on your sandstone when it’s wet and can grow quickly into large colonies.

  • Lichens: black, grey or white spots on sandstone slabs that get larger over time are caused by lichens. A lichen is not a single organism; rather it is a composite organism formed by the symbiosis between different organisms, usually between algae and a fungus. The tiny organisms can be transported by the wind from trees that are close to your paving slabs.

  • Moss: moss are small flowerless plants that typically grow in dense clumps or mats, often in damp or shady locations. Again, moss can be transported by air to your lovely sandstone paving slabs and grows in the dirt between the paving slabs, producing an unsightly green border around each slab.

Don’t use cleaning products that might permanently discolour your sandstone!

When cleaning sandstone paving slabs, it’s really important to avoid using anything that might permanently discolour the slabs. For example, any cleaning product that contains iron is likely to react with the sandstone and can produce a rust colour on the paving slabs. This looks awful and can be difficult to remove. Don’t do it!

Similarly, many fungicides that remove lichens can permanently discolour the sandstone.

Keep it simple

Dirt, moss, and algae can usually be removed using a diluted mixture of household bleach. The bleach should not be used straight out of the bottle. Instead, dilute the bleach in a similar amount of water. Then pour the diluted bleach mixture onto the sandstone slabs and wait for 30 minutes. Then wash the bleach and contaminants away with plenty of water.

The sodium hypochlorite (essentially, liquid chlorine) in the bleach kills the moss and algae, but it’s only a temporary solution; it won’t prevent a new infestation, so it’s important to repeat the process every few months or whenever you think cleaning is required, to keep your sandstone paving looking pristine.

The lichen problem – just add a little elbow grease!

While bleach is every sandstone paving owner’s best friend when it comes to dirt, algae and moss, it won’t destroy the majority of lichens. Instead, this is where a bit of elbow grease is needed.

Lichens can be removed by brushing with a wire brush. Take care though, since wire brushing can affect the appearance of the sandstone. It’s possible to buy fungicides specifically designed for sandstone that will remove lichens. Again, though, make sure you don’t use fungicides that contain iron because the iron can react with and oxidise some of the minerals within the sandstone. And no one likes to see rust-coloured patches on their sandstone slabs!

How about using a power washer?

A power washer can be a great tool for cleaning sandstone paving slabs, especially if you have a large area of sandstone to clean.

Tread carefully here, though: it’s important not to clean sandstone with too much pressure. Some sandstone is quite soft and only needs low pressure cleaning. If the water pressure is too high, you might actually erode some of the sandstone along with the various contaminants. You might need more than one pass to get it really clean, but better that than washing your sandstone away completely.

You can also add chemical cleaners to your power washer. But the same rule applies: make sure that the chemical cleaner doesn’t contain iron.

While commercial sodium hypochlorite cleaners are available, it’s cheaper to use household bleach, again diluted with water in equal parts.

What about sealant products?

There has been much debate about whether you should seal your pavers or whether you should leave them au naturel. Some people recommend that you avoid sealing products, since some can actually increase the chances of staining and discolouration.

However, by using a natural-look sealing product, you can protect against oil, greasy spills and other embedded stains.

Here at FirstLight, we recommend a product called Cementone Natural Stone Sealer. It’s made by Bostik, the adhesive experts, and is a water-based sealer for use on porous stone. It seals natural stone to help prevent staining and reduce efflorescence, which is the build-up of salt deposits that crystallise on the surface of concrete, bricks and stone surfaces.

In short, Cementone provides an excellent resistant barrier to water, oil and dirt.

The final word

Even though sandstone is known for being highly porous, it is also extremely durable and can vastly improve the appearance of your home. So if you’re interested in using sandstone pavers either inside or outside of your home, make sure you follow our simple maintenance and cleaning tips to ensure the sandstone looks better for longer.

FirstLight can help you with all your sandstone paving needs. From choosing and installing your perfect patio, to cleaning, sealing and keeping your sandstone looking beautiful, we’ve got you covered.

So if you’re looking for help and advice with choosing, installing or maintaining sandstone paving in your home, feel free to get in touch with us. Our team is standing by and happy to provide any advice you need.